final traffic modelling report issued 200308

Longbridge Area Action Plan

Traffic Modelling Report

Birmingham City Council

March 2008

Prepared by: ................................................ Approved by: ................................................. Edmund Salt Ian Braddock Graduate Consultant Regional Director Longbridge Area Action Plan

Rev No Comments Date

1 FINAL 20/03/08

Beaufort House, 94/96 Newhall Street, Birmingham, B3 1PB Telephone: 0121 262 1900 Fax: 0121 262 1994 Website: http://www.fabermaunsell.com Job No 60034182 Reference Date Created March 2008 This contains confidential and commercially sensitive information, which shall not be disclosed to third parties. f:\dp\projects\50010tbmd longbridge aap\documents\outgoing\final reports\traffic modelling report\final traffic modelling report (issued 200308).doc

1 Introduction ..................................................................................................................... 3 1.1 Purpose of Report................................................................................................. 3 1.2 Report Structure.................................................................................................... 4

2 Scenario Development ................................................................................................... 6 2.1 Introduction ........................................................................................................... 6 2.2 Matrix Development .............................................................................................. 6 2.3 Scenario 1 Development ...................................................................................... 8 2.4 Scenarios 2 and 3 Development........................................................................... 9

3 Network Results ............................................................................................................ 14 3.1 Introduction ......................................................................................................... 14 3.2 Model Stability..................................................................................................... 14 3.3 Scenario 1 Network Performance....................................................................... 15 3.4 Scenario 2 and 3 Network Performance............................................................. 16 3.5 Network Indicators – Journey Times .................................................................. 19 3.6 Network Indicators – Average Speed and Delay................................................ 24 3.7 Summary of Network Results ............................................................................. 25

4 Sensitivity Option Testing............................................................................................ 27 4.1 Introduction ......................................................................................................... 27 4.2 Matrix Development ............................................................................................ 27 4.3 Option Testing Development .............................................................................. 28 4.4 Option Testing Results ....................................................................................... 28 4.5 Option Test 1 and 2 Network Performance ........................................................ 29 4.6 Network Indicators – Journey Times .................................................................. 31 4.7 Network Indicators – Average Speed and Delay................................................ 36 4.8 Summary of Sensitivity Option Testing Results.................................................. 37

5 Strategic Road Network................................................................................................ 39 5.1 Introduction ......................................................................................................... 39 5.2 Model Development ............................................................................................ 39 5.3 Existing Operation............................................................................................... 40 5.4 Future Traffic Flows ............................................................................................ 42 5.5 Model Stability..................................................................................................... 43 5.6 M42 Junction 1.................................................................................................... 43 5.7 M42 Junction 2.................................................................................................... 48 5.8 M5 Junction 4...................................................................................................... 53 5.9 Summary and Conclusions................................................................................. 60

6 Conclusions and Recommendations.......................................................................... 63 6.1 Introduction ......................................................................................................... 63 6.2 Area-Wide VISSIM Model Conclusions .............................................................. 63 6.3 Strategic Road Network...................................................................................... 65 6.4 Recommendations.............................................................................................. 66

7 Appendix A: Critical Queues on the Network ............................................................ 68 Rose Hill Roundabout (Scenario 1 AM Peak)................................................................. 68 Redhill Road / A441 Redditch Road (Scenario 1 AM Peak)........................................... 69 Longbridge Lane / A441 Roundabout (Scenario 1 AM Peak)......................................... 69 Redhill Road / A441 Redditch Road Roundabout (Scenario 1 PM Peak) ...................... 70 Hopwood Roundabout (Scenario 1 PM Peak) ................................................................ 71 Park and Ride Site / Longbridge Lane (Scenario 1 PM Peak)........................................ 72 Cock Hill Lane Exit (Scenario 2 AM Peak)...................................................................... 72 Longbridge Lane (Scenario 2 AM Peak)......................................................................... 73 Minor Roads North of Longbridge Lane (Scenario 2 PM Peak) ..................................... 73

Table of Contents

Longbridge Lane (Scenario 3 PM Peak)......................................................................... 74 Traffic Flow through AAP Area (Scenario 2 PM Peak) ................................................... 74

8 Appendix B: SRN Matrices........................................................................................... 76 8.1 2005 and 2006 Background Matrices ................................................................. 76 8.2 2021 Background Matrices ................................................................................. 78 8.3 Longbridge AAP Development Matrices – Without Mode Shift .......................... 81 8.4 Longbridge AAP Development Matrices – With Mode Shift ............................... 82

Introduction

Faber Maunsell Longbridge Area Action Plan 3

1.1 Purpose of Report The purpose of this report is to show the impact on the road network of Birmingham City Council’s (BCC) land use options to be included in the Longbridge Area Action Plan (AAP) and propose infrastructure changes to mitigate the majority of the development in the AAP area. The size of the land use development is approximately 290,000sqm and covers a diverse mix of developments. It includes employment, retail, leisure, residential and education. The land use mix breakdown is summarised in Table 1.1. Table 1.1: Land Use Mix Options (Travel Demand Model Report, Faber Maunsell, March 2008)

Land Use Per

North Works Car Park and

West Works

North Works Nanjing

East Works

and Cofton Centre

Employment, B1 sqm

2,850 2,850

Employment, B1a sqm 25,000 10,000

Employment, B1b/c sqm 80,000

Employment, B2 sqm 20,000 10,000 32,300 37,400

Employment, B8 sqm 6,500 9,750

Employment, Other sqm 10,000

Residential Dwelling 350 550 750

Superstore sqm 7,500

Local shops sqm 6,000

Leisure sqm 5,000

Education sqm 24,000

Heritage Employee 100

A local area VISSIM micro-simulation traffic model was developed by Faber Maunsell in 2001 to assess the options and implications of a new link to the M42 motorway to the South. This model has been updated and used to assess the impact of the AAP proposals on traffic behaviour at the full opening year of 2021. The model covers the Longbridge area, including the A38 to the West and A441 to the East (Figure 1.1). The updated model has been validated to a base year of 2006 by Halcrow and signed off by Faber Maunsell as fit for purpose. Details of the 2006 validated model can be found in the Local Model Validation Report (LMVR). The impact was assessed in the AM peak (0745 – 0900) and PM peak (1645 – 1800) for 2021 for three different scenarios (Table 1.2). A sensitivity option test was developed as an alternative approach to provide further support to the conclusions drawn from the three scenarios. The test used a smaller matrix so that the potential impact of the development in the AAP area and network wide could be seen (Table 1.3). In addition to the local area VISSIM model, three separate models have been developed to assess the impact on the strategic road network (SRN). Further information on the SRN is provided in section 5 of this report.

1 Introduction


Table 1.2: Model Scenario Network and Traffic Forecast

Scenario Network Traffic

1 2006 base network with Longbridge park

and ride junction

• 2006 background traffic plus growth

to 2021

• Longbridge Park and Ride forecast

traffic.

2 Proposed network infrastructure and

AAP


to 2021.

• Development traffic with no mode

shift.


AAP


to 2021

• Development traffic with mode shift.

Table 1.3: Option Test Model Network and Traffic Forecast

Option

Test Network Traffic


AAP

• 2006 background traffic

• Development traffic with no mode

shift.


AAP

• 2006 background traffic


1.2 Report Structure

This report should be read in conjunction with the following other reports which provide the

background data for this report:

• Travel Demand Model Report (Faber Maunsell, March 2008);

• Travel Management Strategy (Faber Maunsell, March 2008) and

• Infrastructure Report (Faber Maunsell, March 2008).

The report structure will cover the following sections:

• Scenario Development outlines the methodology for the development of each

scenario model in relation to the area wide VISSIM model;

• Network Results describes the key results of each scenario for selected network

parameters, in relation to the area wide VISSIM model;

• Sensitivity Option Testing discusses the formulation and results of an alternative

matrix model test to highlight the impact of the development in the central AAP area;

• Strategic Road Network sets out the development of VISSIM models to assess the

impact on the SRN together with the results of the operation of each junction for each

scenario;

• Conclusions and Recommendations provides a final summary of the key results

along with possible recommendations for the future.

Scenario Development


2.1 Introduction

This section discusses the development of the three scenarios from the formulation of the

matrices to the network layout. An area-wide VISSIM model was developed for three different

scenarios. The network layout for Scenario 1 is different from Scenario 2 and 3. The difference

between Scenario 2 and 3 is the mode-shift assumptions from the TDM. The matrices used for

the three scenarios are all different.

Faber Maunsell created four separate matrices to input to the VISSIM model:

• Background Traffic with Growth (2006 – 2021);

• Development Traffic with No Mode Shift;

• Development Traffic with Mode Shift;

• Development Traffic for Park and Ride Only.

The purpose of developing three different scenarios was to allow for a comparison to be made

between the models with varying assumptions.

2.2 Matrix Development

Ideally, a strategic Variable Demand Model (VDM) (such as PRISM) would have been used to

derive factors to forecast traffic levels from 2006 to 2021, which was the original approach

recommended. The nature of the PRISM zone structure means that it covers a wide area at a

strategic level. The outputs for the model had a lack of sufficient detail on the micro-scale

required to assess the specific impact of the AAP development on the local area, although

growth factors from the model could have been adapted. However, given the time constraints

to meet the AAP submission deadlines TEMPRO growth factors were adopted, as an

alternative approach.

TEMPRO stands for Trip End Model Presentation Program and is developed by the Department

for Transport (DfT). It allows for fast and efficient access to the national trip end models of

projection in travel demand at a local level, rather than National Road Traffic Forecast (NRTF)

which is growth at a national average. The version of TEMPRO used was 5.0 and the growth

factors derived for each peak can be seen in Table 2.1.

The TEMPRO software uses the base year demographic characteristics of each zone from the

2001 Census of Population. From this, the county / district level projections and the expected

growth factors (EGFs) are used to generate consistent future year planning data at the zonal

level. The EGFs represent the levels of growth that would be expected in each zone, as a

function of the area type of that zone, or the observed changes in employment premises. The

process runs incrementally through time, with coarse-level changes over the next period being

applied to the detailed zone level results of previous scenario. The software is flexible enough

to allow Trip End Model forecasting or back-casting (to 1991) for any required period at any

spatial level given adequate data input.

Table 2.1: TEMPRO 5.0 Growth Factors

Peak TEMPRO 5.0 Growth Factor

AM 1.269

PM 1.260

Only the ‘external to external’ movements were weighted by these factors; it was assumed that

internal traffic growth would be included in the AAP development. Both the ‘lights’ and ‘heavies’

2 Scenario Development


2006 matrices were weighted in this way for movements between external locations (Figure

2.1):

• Zone 1 (A38 Bristol Road West);

• Zone 2 (A38 Bristol Road East);

• Zone 3 (West Heath Road);

• Zone 4 (Rednal Road);

• Zone 5 (A441 Redditch Road);

• Zone 6 (Redhill Road);

• Zone 7 (A441 Birmingham Road);

• Zone 8 (Birmingham Road);

• Zone 9 (B4096 Old Birmingham Road);

• Zone 12 (Tessall Lane);

• Zone 20 (Lickey Square). These external locations were weighted because it was assumed that interventions outside of the immediate model area would impact on travel behaviour through the area. Interventions including the Northfield Relief Road, Selly Oak Relief Road and Technology Corridor will influence a change in travel behaviour, resulting in an expected increase in traffic through the area. TEMPRO traffic forecasting projection includes growth associated with development that was envisaged at the time of publication; with this in mind it is common to constrain total growth from the base to the TEMPRO forecast. However, in this case it was assumed that the AAP development was not in the TEMPRO forecast and therefore we have not constrained growth to the TEMPRO forecast. By including both the development and external to external growth it was considered a sound methodology which took into account the impact of other known developments along the A38 and outside the scope of the model. Within the area of this assessment the use of NRTF growth factors was not considered as appropriate along the A38 and A441 as the nature of the trips along these routes, in the vicinity of Longbridge, are more locally related rather than long distance movements. Once the growth factors were applied, assumptions related to linked, pass-by and diverted trips to and from the development were made and the matrix manipulated to avoid double counting of trips. These assumptions are discussed in the TDM Report (Faber Maunsell, March 2008).

The matrix for background growth from 2006 to 2021 does not include any development on the

land that was occupied by Rover. Therefore the background growth does not include

development that may have replaced Rover by the future year. This means that the traffic

forecast for Scenario 1 could under represent the actual future year traffic levels. However, this

potential for under representation of future flows is offset by the assumption made regarding

growth in external to external trips, which is realistic given the spare capacity on the network

made available by the absence of Rover trips. The development traffic was generated from the Travel Demand Model (TDM), which included the proposed land use scenario. The development of the TDM is discussed separately in the TDM Report (Faber Maunsell, March 2008). No change in HGV trips was predicted from the TDM; however, the numbers of trips were increased from 2006 using TEMPRO factors in the same way as car trips. Although this is not conventional, it was considered acceptable in this case because there were not many HGV trips and those were assumed to be locally related. Usually NRTF is used to assess the potential HGV growth either to a low, central or high forecast level. The comparison between the TEMPRO factors used and NRTF factors for HGV growth are shown in Table 2.2. It can be seen that the TEMPRO factors adopted are similar if not more, so the model approach applied to HGV growth is robust. Table 2.2: HGV Growth Factors

Peak TEMPRO 5.0 NRTF (Low) NRTF (Central) NRTF (High)

AM 1.269 1.201 1.267 1.324

PM 1.260 1.201 1.267 1.324


This matrix development exercise resulted in the following traffic levels (Table 2.3 and 2.4). Table 2.3: Matrix Totals for AM Peak

Matrix Scenario 1 Scenario 2 Scenario 3

2006 Background Traffic 8993 8993 8993

2021 Growth 1313 1313 1313

Development Traffic with No Mode Shift 326* 5648 -

Development Traffic with Mode Shift - - 4891

Pass-By and Diverted Trips -43** -571 -571

Total Cars Modelled 10589 15370 14624

Heavies Modelled 188 188 188

Table 2.4: Matrix Totals for PM Peak

Matrix Scenario 1 Scenario 2 Scenario 3



Development Traffic with No Mode Shift 326* 5307 -

Development Traffic with Mode Shift - - 4728

Pass-By and Diverted Trips -43** -678 -678

Total Cars Modelled 10724 15070 14491

Heavies Modelled 51 51 51

*Park and Ride traffic only.

**Park and Ride Pass-By and Diverted Trips only.

2.3 Scenario 1 Development

Scenario 1 models the current road network with the inclusion of the park and ride facility. It is assumed that the park and ride would be built in the future year even if the AAP did not go ahead. This is modelled as a simple three-arm signalised junction. Further details of the Park and Ride facility can be found in the Travel Demand Model and Rail Strategy Reports. The scenario assumes that there will be no other major junction redesign in the future if the AAP is not implemented. The traffic levels modelled are 2006 background traffic plus background traffic growth from 2006 to 2021 and traffic for the park and ride.

It is common practise within Birmingham City for background growth not to be applied to base

traffic levels given the current congested network. However, in this instance background

growth has been applied due to the reduced activities on the existing Longbridge site. It is

considered that the lack of trips associated with the former use of the site would result in latent

demand rising on the network associated with:

• Northfield Relief Road;

• High Tech Corridor;

• Queen Elizabeth Hospital.

2.3.1 Network Changes

The initial model included twenty zones some of which had more than one entry or exit location in the network. However, to enable a future year model it was reconfigured to replace these multiple entry and exit locations with new zones. Therefore, the number of zones representing the local area with no proposed development increased from 20 to 27. This can be seen from Figure 2.1.

The park and ride site was coded into the model as a new zone (number 29) to the north of Longbridge Lane, which can also be seen in Figure 2.1.


2.3.2 Signal Review

The new park and ride site required a signal review for the new junction. The signals were reviewed to include acceptable inter-greens and accommodate pedestrian movements. The signals in the rest of the network were optimised for 2021 conditions.

2.3.3 Routing Decisions

A dynamic assignment of routing decisions was run to find acceptable paths between zones. The majority of routes with the heaviest traffic flows used the A38 Bristol Road, B4096 Longbridge Lane and A441 Redditch / Birmingham Road. Some routes were closed because they used unrealistically long diversions; such as driving three sides of a square. However, acceptable ‘rat-runs’ were left in the model as paths. By ensuring acceptable routing decisions the performance of the model is considered realistic and acceptable.

2.4 Scenarios 2 and 3 Development

Scenarios 2 and 3 reflect the network if the AAP is developed in line with the proposed infrastructure changes (see section 2.4.1 below). Traffic levels in these scenarios built upon those from scenario 1. In addition to 2021 traffic and the park and ride, the forecast AAP trips (minus pass-by and diverted assumptions) were added. The difference between scenarios 2 and 3 is the inclusion of the mode-shift assumptions from the TDM (see Travel Demand Model Report, Faber Maunsell, March 2008).

2.4.1 Network Changes

As part of the AAP, significant alterations to the highway network are proposed. These involve considerable realignment of the current road network and the introduction of a new bus only route across the A38. The new alignments are outlined in the Infrastructure Report (Faber Maunsell, March 2008). The model was changed so that it was consistent with the infrastructure proposals as set out in the infrastructure report (Drawing PI ELMP-T000-1042). The infrastructure proposals are improvements initially recommended by Halcrow which have been developed further and added to as part of the work undertaken. A zone (28) was added south of Longbridge Lane, opposite the park and ride plus development site. Additional site access was added around the West Works Link. Zone 32 represents site access inside the West Works Link and zone 33 outside of West Works Link (Drawing PI ELMP-T000-1042). Following some initial tests, it became clear that traffic exiting the West Works Link required the option to use the roads north of the A38 in addition to leading directly onto the A38. Therefore, in consultation with BCC it was decided to extend the shared bus lane to link up with Hollymoor Way to provide a small area of buffer network to allow traffic for the West Works to exit only. The new links were closed to through traffic so only vehicles from the relevant zones could use them. The road was not to be used as an alternative for vehicles wishing to bypass the A38. By closing these routes to through traffic it was considered that this methodology did not alter the integrity of the forecasting work as the assignment for background traffic was unaltered.

As part of the infrastructure proposals, alterations are proposed to Longbridge Lane, removing

two roundabouts at the Longbridge Lane / Coombes Lane and Longbridge Lane / Groveley

Lane junctions, and replacing them with signals. At these junctions the Longbridge Lane will be

widened to two lanes through the signals but the remainder of Longbridge Lane remains as

single lane.


2.4.2 Additional Junction Improvements

Analysis of Scenario 1 showed that certain junctions could have a detrimental effect on the overall network performance if more traffic was loaded into the area. It was decided in consultation with BCC to redesign identified junctions in an attempt to improve the overall network performance. The junctions selected for mitigation because of their strategic importance within the network were:

• B4120 / A441 (Hopwood roundabout)

• Longbridge Lane / A441 Birmingham Road roundabout

The Hopwood roundabout was identified for improvement because it was envisaged that the vehicles held up because of the roundabout’s poor capacity could have a detrimental impact on the M42 Junction 2 motorway junction. The Longbridge Lane / A441 Birmingham Road roundabout was selected because it was seen as a problem in Scenario 1, causing queuing and delays along the A441 and Longbridge Lane. It was envisaged by alleviating any problems at this junction, the flow of traffic along Longbridge lane and A441 would be improved even if there was more traffic in the network. These two junctions are currently roundabouts. Several improvements options were considered for each junction. Signalisation of the Hopwood junction was considered but due to highway boundary constraints and the design requirements to accommodate high speeds of traffic on the A441 this was not feasible. Therefore the junction was kept as a roundabout and redesigned to have an increased capacity along the A441 movements. The preliminary layout of this junction is shown in Drawing 50010TBMD_001. Longbridge Lane / A441 Birmingham Road and was initially redesigned with an increased capacity (Drawing 50010TBMD_002) but this did not significantly improve capacity. The junction was then redesigned with signals. The preliminary layout is shown in Drawing 50010TBMD_003.

2.4.3 Routing Decisions

A dynamic assignment has been run to find acceptable paths. These paths were checked against the Scenario 1 model to ensure consistency between the models. Due to the heavily congested nature of the network it was important to have the similar paths as before otherwise the results would not be comparable. It was important to close off the possibility of ‘rat-runs’ using the new links behind the A38 for external to external trips because otherwise the results would again not be comparable with Scenario 1. The links were to be used for traffic exiting the site access around the West Works Link as an alternative route if they wished to join the A38 to travel to either the city centre or M5 junction 4. This approach has been agreed with BCC.

2.4.4 Signal Review

The new AAP infrastructure design included new signalised junctions. All eleven signal groups in the network have been reviewed and the timings re-phased to include acceptable inter-greens and accommodate pedestrian movements. Two new signalised junctions in the AAP area were also reviewed to include pedestrian movements.

2.4.5 Scenario Optimisation

After loading the new traffic levels in the altered network, time was taken to manually optimise the operation of the network.

2.4.5.1 Signal Timing and Phasing To ensure optimisation of the network, the amount of green-time at each signal is important. The signal timings have been balanced so queues did not have a detrimental impact on the surrounding area. At several junctions an all red phase is included to allow for pedestrian


movements. In reality design proposals could allow for a walk-with pedestrian movement which would increase green time and reduce delays. It is also proposed to implement SCOOT / MOVA at the signalised junctions. SCOOT (Split Cycle Offset Optimisation Technique) is a fully adaptive traffic control system which uses data from vehicle detectors and optimises traffic signal settings to reduce vehicle delays and stops. SCOOT is able to respond to variations in traffic demand on a cycle-by-cycle basis. It responds rapidly to changes in traffic, but not so rapidly that it is unstable. Results have shown that SCOOT achieves an average saving in delay of about 12% when compared with up-to-date fixed time plans. Research by Bell and Bretherton (1986) suggests that SCOOT is likely to achieve an extra 3% reduction in delay for every year that a fixed-time plan ages. Since SCOOT is designed to adapt automatically to compensate for ageing and incident effects, it is reasonable to expect that, in many practical situations, SCOOT will achieve savings in delay of 20% or more. MOVA (Microprocessor Optimised Vehicle Actuation) is a method of controlling traffic signals at junctions. It is a well established strategy for the control of traffic light signals at isolated junctions. It is the required signal control method for new junctions on the trunk road network that are not normally part of a linked network.

MOVA is particularly well suited to the following conditions:

• Sites with high traffic flow.

• Sites experiencing capacity difficulties under Vehicle Actuated (VA) control with congestion on one or more approaches.

• Sites with high speed approaches and/or red compliance problems.

• Where more than one junction is situated too close to be considered as isolated, there are ways in which two or more junctions can be linked by the use of MOVA control.

MOVA will generally provide in the region of 20% reduction in delays. A TRL research project found that an average 13% decrease in delay at 20 junctions running with MOVA compared with standard VA. This is based on the TRL study "RR279 MOVA: The 20-site trial” by J R Peirce and P J Webb. 1990". It was found that if movements along the A38 and in the AAP area were optimised, the model performed well along this route. By avoiding excessive queuing along the A38 the movement of vehicles was adequate along this route. In the AM peak model the eastbound movement along the A38 has been given more green-time than the westbound movement. This was because of the volume of traffic that travels towards the city during this period. In the PM peak a large volume of traffic travels out of the city along the A38. However there is also a high volume travelling towards the city. Therefore the signal timings in both directions were balanced to ensure a continual flow of traffic in both directions to avoid queues in the AAP area. To optimise the model performance it was important that the signal timings are linked where possible. The key traffic signals, to ensure a continuous flow of traffic along the A38 through Longbridge to the city centre (Figure 2.2), are:

• Signal Control 1: A38 / Ashill Road;

• Signal Control 2: A38 / Longbridge Lane / West Works Link;

• Signal Control 3: A38 / Superstore;

• Signal Control 4: A38 / Tessall Lane;

• Signal Control 6: A38 / West Works Link;

• Signal Control 7: Lickey Road / Lickey Road Link;

• Signal Control 8: A38 / Longbridge Lane / Park and Ride Site;

• Signal Control 10: A38 / Lickey Road Link. There is a large amount of traffic exiting the site access around the West Works Link during the PM peak. However, due to the flow of traffic along the A38 the green-time given to West Works Link at the A38 / Longbridge Lane / West Works Link interchange is significantly reduced. A decision was made to keep the A38 flowing at the expense of traffic attempting to exit the new development. The inclusion of the additional network (as described in section 2.4.1) helped alleviate the problem of excessive queuing of vehicles exiting the new developments.


The traffic behaviour along Longbridge Lane was also important to network performance; however, due to the congested roads around Longbridge Lane, particularly Cofton Road, Lilley Lane and Redhill Road optimisation was difficult. The traffic signals along Longbridge Lane do have an effect on the network performance, yet both signals require an all-red phase, reducing the amount of green-time available (Figure 2.2):

• Signal Control 11: Longbridge Lane / Coombes Lane;

• Signal Control 12: Longbridge Lane / Groveley Lane. Longbridge Lane has been given priority in terms of green-time because if queues form it would impact on the A38 and therefore affect the whole network.

2.4.5.2 A38 Bristol Road / AAP The AAP area has been modelled according to the preliminary design proposed in the Infrastructure Report (Faber Maunsell, March 2008). Throughout much of the AAP area the A38 is 3 lanes wide. This allows a high volume of traffic to travel through the area. The lane change decisions were all checked so that the driver behaviour through the area was optimised.

2.4.5.3 Park and Ride and Development Site A large volume of traffic exits the site over the peak periods. However, traffic is held up in the park and ride plus development site by the signal timings; this is to keep Longbridge Lane as free-flowing as possible so not to block the entire network. It is not feasible to give enough green-time to the three arms and allow an all-red pedestrian phase. The junction in its current design does not have sufficient capacity for the level of traffic predicted to exit the site north of Longbridge Lane. There is scope to provide a secondary access to the park and ride from Tessall Lane. This possible mitigation would reduce the problem of having a high proportion of vehicles attempting to exit the park and ride plus development site from one exit.

Network Results


3.1 Introduction

This section discusses the key results for each scenario. The performance of the network in each scenario and peak varies as the traffic assignments and volumes differ. Different parameters can be used to evaluate the network performance:

• Held up traffic. The traffic unable to enter the network highlights a congested network or perhaps one junction that is over capacity. Traffic is held up at the end of a VISSIM model run when either the demand is higher than the saturation point of the link the traffic enters on to; or when queues form in the network and physically stop traffic assigning on to the network. In the case of this model, both contributed to some traffic remaining in the car parks at the end of the model assignment.

• Queues. A queue becomes a problem when it hinders and affects other junctions in the network or causes a significant delay and re-routing of traffic. The formation of queues within the network highlights junctions which cannot cope with the traffic demand in the current design. A junction which cannot cope with the traffic levels may be the reason for a congested network. Therefore it is important to know where lengthy queues form, which can impact on other parts of the network. Appendix A contains images of queuing traffic in the various scenarios.

• Journey time through the network, from key locations, shows the time to travel through the network. The different scenarios can be compared to see if the development has had any significant impact on journey time along key strategic routes.

• Average network speed. This gives an indication of the congestion in the network, with slower vehicle speeds related to more congestion.

• Average delay per vehicle. The amount of delay experienced per vehicle during the journey through the network. The more congested the network and queues the likelihood of more delay.

3.2 Model Stability

The nature of dynamic assignment modelling means that the reliability of results can vary if

there is a lack of stability in the models. The stability of a model is based on the model

convergence level. It is accepted that for a stable model to provide reliable results a

convergence of over 97% is required. Each scenario option needs similar convergence levels

for the comparison of results to be valid.

The model convergence results are acceptable and show a very high level of convergence

(Table 3.1). Only the AM peak in Scenario 1 is less than 99% converged but it still has a good

level of convergence at 98.87%. The range of convergence between the models is negligible

(1.12%) so the comparison of results is reliable.

Table 3.1: Model Convergence

Scenario 1 Scenario 2 Scenario 3

AM Peak (%) PM Peak (%) AM Peak (%) PM Peak (%) AM Peak (%) PM Peak (%)

98.87 99.99 99.83 99.89 99.95 99.64

3 Network Results


3.3 Scenario 1 Network Performance

3.3.1 Total Traffic Held up

Vehicles are unable to enter the network at a number of locations because of queues and poor junction capacity. Table 3.2 shows the total amount of traffic held up and where during the peak periods. However, it should be noted that the level of traffic modelled in this Scenario may potentially have been under represented as described in section 2.2. Therefore the condition in the future year could be much worse than forecast in Scenario 1. Table 3.2: Number of Vehicles Unable to Enter the Network (Scenario 1)

Peak Zone Vehicles Total

Vehicles

Percentage of

Total Traffic (%)

3 West Heath Road 105

7 A441 Birmingham Road northbound 53

9 B4096 Old Birmingham Road 105 AM

20 Lickey Square 65

329 3.1

5 A441 Birmingham Road southbound 176 PM

7 A441 Birmingham Road northbound 171 347 3.2

The following section provides further details on the locations where traffic is held up on the

network; together will details about queuing on the network as included in Appendix A.

3.3.2 AM Peak Observations

Queues form along Longbridge Lane from Longbridge Lane / A441 Birmingham Road roundabout due to the inadequate capacity (Appendix A). The queue goes back to the junction with Groveley Lane / Cofton Road. The roads north of Longbridge Lane are congested during the peak, with queues along Redhill Road and Cofton Road.

3.3.2.1 West Heath Road

Traffic is unable to enter the network from West Heath Road because of two junctions, which cause vehicles to queue back hindering the traffic flow:

• Redhill Road / A441 Redditch Road roundabout

• Longbridge Lane / Groveley Lane / Cofton Road interchange The low capacity of the Redhill Road / A441 Redditch Road roundabout means queues form back along Redhill Road towards West Heath Road. In its current configuration all the traffic is unable to travel through the roundabout each experiencing delay through queuing (Appendix A).

The Longbridge Lane / Groveley Lane / Cofton Road interchange signals incorporate an all-red

pedestrian phase which limits the amount of green-time available. Due to the strategic

importance and high vehicle demand along Longbridge Lane, it was important to allow more

green-time to this road to reduce congestion. Therefore the Cofton Road arm had a limited

amount of green-time which caused queuing along the road, hindering West Heath Road.

3.3.2.2 A441 Birmingham Road northbound

Hopwood roundabout also has capacity related issues due to the high traffic demand at the

junction. Vehicles are unable to enter the network at this location because the low capacity of

this roundabout means the amount of traffic which can travel through the junction is restricted.


3.3.2.3 B4096 Old Birmingham Road / Lickey Square

Both these zones, west of Rose Hill roundabout have traffic unable to exit. The reason is because the capacity of the roundabout in its current design is unable to cope with the volume of traffic that is forecast to use it (Appendix A). Queues form from this roundabout during the peak hour, along Rose Hill, which stops vehicles from exiting the zones (Figure 3.2).

3.3.3 PM Peak Observations

Longbridge Lane does not have any significant queues; although small queues do form around the Park and Ride plus Development junction (Appendix A). Despite the signals on Longbridge Lane having a longer green-time compared to the park and ride exit, queues still form due to the demand of vehicles travelling along the road.

3.3.3.1 A441 Redditch Road southbound / A441 Birmingham Road northbound

The A441 has traffic unassigned to the network in both directions. The reason is because of the capacity of two roundabouts (as discussed in section 3.3.2.2):

• Redhill Road / A441 Redditch Road roundabout;

• Hopwood roundabout. Along the A441 southbound, traffic queues back to the Redhill Road / A441 Redditch Road roundabout from the Hopwood roundabout (Appendix A). The roundabout at Longbridge Lane / A441 Birmingham Road also hinders the traffic flow along the A441, which increases the problem of queuing.

3.4 Scenario 2 and 3 Network Performance

3.4.1 Total Traffic Held up

The total number of vehicles held up during the peak periods and at which zones is shown in Tables 3.3 and 3.4. The total amount held up is higher in both scenarios than Scenario 1 for the respective peak periods. However, the percentage of traffic held up in the PM peak for Scenario 3 (2.5%) is less than Scenario 1. With more than half of this traffic held up at zone 29 (Park and Ride plus Development Site) it shows that improvements made to the network have helped reduce the number of vehicles held up in comparison to the size of the matrix. Also in the PM peak, Scenario 2 only has 0.5% more traffic held up compared to Scenario 1. Table 3.3: Number of Vehicles Unable to Enter the Network (Scenario 2)


Vehicles

Percentage of

Total Traffic (%)

5 A441 Birmingham Road southbound 196


9 B4096 Old Birmingham Road 360

20 Lickey Square 117

AM

24 Cock Hill Lane 445

1519 9.9

4 Rednal Road 69


29 Park and Ride plus Development Site 310

561 3.7


Table 3.4: Number of Vehicles Unable to Enter the Network (Scenario 3)


Vehicles

Percentage of

Total Traffic (%)

5 A441 Birmingham Road southbound 186



20 Lickey Square 92

AM


1134 7.8

4 Rednal Road 65


29 Park and Ride plus Development Site 185

361 2.5

The following section provides further details on the locations where traffic is held up on the

network; together with details about queuing on the network as included in Appendix A.

3.4.2 AM Peak Observations The zones where traffic is held up are all external; none of them are in the AAP area. The AAP area and A38 Bristol Road performs adequately during the period with no traffic held up and only transient queues forming. The general network performance in the peak is acceptable. Queues do form in Scenario 2 in both directions along Longbridge Lane, A441 Northbound and along Redhill Road and Cofton Road but this is due to the limited capacity and performance of Longbridge Lane (Appendix A). There are two sets of signals located on Longbridge Lane both of which require an all-red phase for pedestrian movements. This reduces the amount of green-time possible in each cycle, which results in queues forming. These signals, particularly at the Longbridge Lane / Groveley Lane / Cofton Road interchange have a similar impact in Scenario 3, albeit on a lesser scale, causing queues on some of the surrounding minor roads.

3.4.2.1 A441 Redditch Road southbound / A441 Birmingham Road northbound

Traffic is held up in the AM peak due to the insufficient capacity of the roundabouts where the traffic enters:

• Redhill Road / A441 Redditch Road roundabout;

• Hopwood roundabout. The roundabouts in their current design are unable to cope with the volume of traffic demand. The Redhill Road / A441 Redditch Road roundabout is unable to cope with the traffic forecast in Scenario 1, so with no improvements made at this roundabout, queuing traffic is inevitable (Figure 3.6).

The A441 Birmingham Road northbound has traffic held up despite the Hopwood roundabout’s

capacity being improved from the current layout. Despite the capacity of the roundabout

increasing, the volume of forecasted traffic is still too heavy for the roundabout to cope.

3.4.2.2 B4096 Old Birmingham Road and Lickey Square

The roundabout at Rose Hill has queuing in Scenario 1, so with no improvements made at this roundabout, it is expected that traffic would queue, affecting the B4096 Old Birmingham Road and Lickey Square.

3.4.2.3 Cock Hill Lane Cock Hill Lane has the highest proportion of traffic held up at 74.8% and 44.1% for Scenario 2 and 3 respectively. This is due to the high volume of traffic that travels eastbound along the A38 East which opposes the flow at the give-way line where Cock Hill Lane enters (Appendix A).


3.4.3 PM Peak Observations In the PM peak there are fewer vehicles held up than in the AM peak at three zones; however unlike the AM peak, one of these zones is in the AAP area. The zones with traffic unassigned to the network are different to those in Scenario 1. For instance, A441 Birmingham Road northbound in Scenario 2 and 3 do not have any vehicles unassigned to the network. This is because of the improvements made to the Hopwood roundabout. The increased capacity allowed extra vehicles to enter the network compared to Scenario 1; which in itself means that the queue that forms in Scenario 1 southbound along the A441, because of the insufficient capacity of the roundabout, is removed. The performance of the AAP area and Bristol Road is adequate with no major queues. The phasing of the signals ensures that there is a steady continual flow of traffic through the area during the peak (Appendix A).

The general network performance in both scenarios is very congested. The areas of worst

congestion contribute to have a detrimental effect on the overall network performance during

the peak (Figure 3.8).

3.4.3.1 Rednal Road and A441 Redditch Road southbound The amount of traffic in the vicinity around Rednal Road and A441 Redditch Road restrict trips from exiting these zones as they enter directly onto roundabouts. Queues forms (Figure 3.8) from:

• Longbridge Lane / Groveley Lane junction;

• Longbridge Lane / A441 Birmingham Road roundabout;

• Rednal Road / Redhill Road roundabout;

• Redhill Road / A441 Redditch Road roundabout. These junctions hinder the flow of traffic in the area (Appendix A). Queues form around these junctions and also down the A441, but not as far back as Hopwood roundabout. This results in traffic unable to exit from Rednal Road and A441 Redditch Road southbound. This area has traffic unassigned in Scenario 1 because of the poor capacity of the junctions, particularly the roundabouts north of Longbridge Lane. Therefore, as there was no mitigation at these roundabouts, the queues and congestion is expected. Longbridge Lane is very congested during the peak with traffic tailing as far back as the Park and Ride plus Development junction. The signals along Longbridge Lane contribute to the queues because they accommodate pedestrian movements. This restricts the amount of green-time available for vehicle movements. The Longbridge Lane / Groveley Lane / Cofton Road interchange signals are a particular problem because there is a high demand through the junction in both directions along Longbridge Lane and from Cofton Road (Appendix A). The Longbridge Lane / Coombes Lane / Turves Green interchange signals also cause traffic to queue back towards the Park and Ride plus Development Site. These junctions in there current designs have a detrimental effect on the surrounding area.

3.4.3.2 Park and Ride plus Development Site Traffic held up at the Park and Ride plus Development site is expected; as part of optimising the A38 Bristol Road, the green-time at the A38 / Longbridge Lane / Park and Ride plus Development site interchange is reduced for that movement. In order to keep the flow of traffic along Bristol Road and Longbridge Lane moving, it is important to allow more green-time to those movements. Queues that form along Longbridge Lane westbound hinder traffic exiting the Park and Ride plus Development site because the queues back up to the exit. Despite traffic unable to exit the northern arm of this junction during the peak, the site is not to be used just for park and ride traffic. In Scenario 1 only the park and ride traffic was modelled


(326 vehicles). However, as part of the development, this site will also be used which more than doubles the previous number of trips (769 and 663 for Scenario 2 and 3 respectively).

3.5 Network Indicators – Journey Times

The performance of the network can be judged by journey time for certain movements through the area. Five locations were selected, due to their strategic importance:

• A - A38 Bristol Road East;

• B - A441 Redditch Road;

• C - Hopwood Roundabout;

• D - Rose Hill Roundabout;

• E - A38 Bristol Road West.

These locations can be seen in Figure 3.9. The journey time has been recorded between each of the above Origin / Destination (OD) locations. The importance of the routes varies depending on the peak period. The journey times for Scenarios 2 and 3 have been compared against Scenario 1 to determine if the development had any significant impact on the journey time along strategic routes. The performance criteria for assessing if the development had a negative impact on the network along strategic routes are:

• 2 minutes or more increase in journey time; and

• 10% change.

3.5.1 AM Peak Journey Time

The existing journey times in minutes between each OD pair for the three Scenarios in the AM

peak are shown in Table 3.5, 3.6 and 3.7. The total journey time through the key strategic

routes is shown in Table 3.8.

Table 3.5: Average Car Journey Time (AM Peak) for Scenario 1

Average Car Journey Time (minutes)

Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 10.97 9.79 5.67 4.26

A441 Redditch

Road 15.12 0.00 7.64 15.57 18.77

Hopwood

Roundabout 11.45 3.45 0.00 0.00 0.00

Rose Hill

Roundabout 15.77 23.20 0.00 0.00 15.54

A38 Bristol

Road West 4.97 16.94 0.00 5.60 0.00




Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 12.31 13.02 8.53 7.59

A441 Redditch

Road 17.29 0.00 10.69 17.82 18.82

Hopwood

Roundabout 12.34 6.33 0.00 0.00 0.00

Rose Hill

Roundabout 20.64 25.52 0.00 0.00 20.26

A38 Bristol

Road West 5.65 14.90 0.00 7.48 0.00



Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 10.93 10.95 7.03 6.24

A441 Redditch

Road 14.51 0.00 9.71 16.79 17.63

Hopwood

Roundabout 11.54 5.16 0.00 0.00 0.00

Rose Hill

Roundabout 20.82 24.46 0.00 0.00 19.50

A38 Bristol

Road West 5.10 13.82 0.00 7.01 0.00

Table 3.8: Total Journey Time through the Key Strategic Routes (AM Peak)

Scenario Journey Time (minutes)

1 184.7

2 219.2

3 201.2

The difference in journey time and percentage change for Scenario 2 and 3 compared to Scenario 1 in the AM peak is shown in Table 3.9 and 3.10. A negative number means Scenario 2 or 3 is faster for that particular OD pair. The percentage change is in brackets. The total journey time difference and percentage change between Scenario 2 and 3 against Scenario 1 is shown in Table 3.11.


Table 3.9: AM Peak Journey Time Difference for Scenario 2 compared to Scenario 1

Journey Time Difference (minutes) and Percentage Change (%)

Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 1.34 (12.2) 3.23 (33.0) 2.86 (50.4) 3.33 (78.0)

A441 Redditch

Road 2.17 (14.3) 3.05 (39.8) 2.25 (14.5) 0.05 (0.3)

Hopwood

Roundabout 0.89 (7.8) 2.89 (83.8) 0.00 0.00

Rose Hill

Roundabout 4.87 (30.9) 2.32 (10.0) 0.00 4.72 (30.4)

A38 Bristol

Road West 0.68 (13.7) -2.04 (-12.0) 0.00 1.88 (33.6)

Table 3.10: AM Peak Journey Time Difference for Scenario 3 compared to Scenario 1

Journey Time Difference (minutes) and Percentage Change (%)

Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East -0.04 (-0.4) 1.16 (11.8) 1.36 (24.0) 1.98 (46.3)

A441 Redditch

Road -0.61 (-4.0) 2.07 (27.0) 1.22 (7.8) -1.14 (-6.0)

Hopwood

Roundabout 0.09 (0.8) 1.71 (49.7) 0.00 0.00

Rose Hill

Roundabout 5.05 (32.0) 1.27 (5.5) 0.00 3.95 (25.4)

A38 Bristol

Road West 0.14 (2.7) -3.12 (-18.4) 0.00 1.41 (25.3)

The figures highlighted in bold in Table 3.9 and 3.10 indicate where we consider a significant change in journey times should be noted according to the criteria set out in section 3.5. Table 3.11: Total Journey Time Difference through the Key Strategic Routes (AM Peak)

Scenario Comparison Journey Time Difference (minutes) Percentage Change (%)

Scenario 2 compared to 1 + 34.5 + 19


3.5.2 PM Peak Journey Time

The existing journey times in minutes in the PM peak for the three Scenarios are shown in

Table 3.12, 3.13 and 3.14. The total journey time through the strategic routes is displayed in

Table 3.15.


Table 3.12: Average Car Journey Time (PM Peak) for Scenario 1


Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 5.59 10.14 5.81 4.21

A441 Redditch

Road 21.52 0.00 13.20 23.34 23.42

Hopwood

Roundabout 11.77 3.12 0.00 0.00 0.00

Rose Hill

Roundabout 8.44 12.43 0.00 0.00 9.14

A38 Bristol

Road West 3.78 9.21 13.52 6.48 0.00



Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 12.66 14.45 9.42 4.81

A441 Redditch

Road 17.31 0.00 11.61 20.69 19.67

Hopwood

Roundabout 13.31 7.89 0.00 0.00 0.00

Rose Hill

Roundabout 7.95 17.56 0.00 0.00 7.62

A38 Bristol

Road West 6.02 18.40 20.20 12.94 0.00



Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 12.69 13.55 8.67 4.55

A441 Redditch

Road 15.36 0.00 8.84 18.53 18.53

Hopwood

Roundabout 12.79 8.03 0.00 0.00 0.00

Rose Hill

Roundabout 6.96 14.11 0.00 0.00 7.90

A38 Bristol

Road West 4.98 17.63 18.78 10.49 0.00


Table 3.15: Total Journey Time through the Key Strategic Routes (PM Peak)

Scenario Journey Time (minutes)

1 185.1

2 222.5

3 202.4

The journey time comparison and percentage change between the Scenarios for the PM peak

is shown in Tables 3.16 and 3.17. The total journey time difference and percentage change is

summarised in Table 3.18.

Table 3.16: PM Peak Journey Time Difference for Scenario 2 compared to Scenario 1

Average Car Journey Time (minutes) and Percentage Change (%)

Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 7.07 (126.5) 4.31 (42.5) 3.61 (62.2) 0.60 (14.3)

A441 Redditch

Road -4.21 (-19.6) -1.59 (-12.0) -2.65 (-11.3) -3.74 (-16.0)

Hopwood

Roundabout 1.55 (13.1) 4.77 (153.2) 0.00 0.00

Rose Hill

Roundabout -0.49 (-5.8) 5.13 (41.3) 0.00 -1.52 (-16.6)

A38 Bristol

Road West 2.24 (59.4) 9.18 (99.7) 6.69 (49.5) 6.47 (99.8)

Table 3.17: PM Peak Journey Time Difference for Scenario 3 compared to Scenario 1


Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 7.10 (127.1) 3.41 (33.6) 2.86 (49.3) 0.34 (8.0)

A441 Redditch

Road -6.16 (-28.6) -4.36 (-33.0) -4.81 (-20.6) -4.89 (-20.9)

Hopwood

Roundabout 1.03 (8.7) 4.91 (157.5) 0.00 0.00

Rose Hill

Roundabout -1.48 (-17.5) 1.68 (13.5) 0.00 -1.23 (-13.5)

A38 Bristol

Road West 1.20 (31.8) 8.42 (91.4) 5.26 (38.9) 4.01 (61.9)

The bold figures in Table 3.16 and 3.17 indicate where there is a significant change in journey

time according to the criteria defined in section 3.5.

Table 3.18: Total Journey Time Difference through the Key Strategic Routes (AM Peak)

Scenario Comparison Journey Time Difference (minutes) Percentage Change (%)



3.5.3 Journey Time Summary From the analysis of the above tables, Scenario 2 clearly has a major impact (20% increase in journey time) on the network chosen which is offset to acceptable levels in Scenario 3. This


emphasises the importance of demand management, as a less than 10% increase in journey time is typically within accepted day to day variations. The routes with the largest impact in Scenario 2 are:

• A38 Bristol Road East;

• A441 Redditch Road;

• Rose Hill Roundabout. Journeys from the A38 Bristol Road East in the AM and PM peak are slower. This could be as a result of the optimisation of Bristol Road eastbound in the AM peak, which restricts the traffic flow from Bristol Road East. In the PM peak the congestion along Longbridge Lane and the surrounding roads affect the journey time, as highlighted by the negative impact to A441 Redditch Road journeys. This emphasises that improvements would be required along this stretch of road to mitigate the increase in travel demand.

3.6 Network Indicators – Average Speed and Delay

The level of congestion in the network can be demonstrated by how much it affects the speed of each vehicle and delay per journey for each vehicle. The more congested the network, the slower the average network speed and more delay expected.

3.6.1 AM Peak

The average network car speed for each scenario can be seen in Table 3.19. Scenario 1 is the

fastest, which is expected as it does have the least amount of traffic in the network and thus

congestion. The scenarios with the development trips do have a slower average speed, but

only by 3 kph and 0.1 kph for Scenario 2 and 3 respectively.

Scenario 3 is only 0.1 kph slower than Scenario 1 despite approximately 4000 extra trips. This

shows that the development trips have been mitigated through the adoption of the network

changes and demand management, as the average network speed is no worse than with no

development trips.

Table 3.19: Average Car Speed (AM Peak)

Scenario Average Speed (kph)

1 27.5

2 24.5

3 27.4

The average delay per vehicle during each trip is shown in Table 3.20. Scenarios 1 and 3 have

the smallest delay per vehicle at 4 minutes. Scenario 2 has only 0.8 minutes more delay per

vehicle at 4.8 minutes. The development trips in Scenario 3 have been mitigated in terms of

delay experienced, and in Scenario 2 the delay is slightly more than Scenario 1 so the

development has had an impact on network performance.

Table 3.20: Average Delay per Vehicle (AM Peak)

Scenario Average Delay (minutes)

1 4.0

2 4.8

3 4.0


3.6.2 PM Peak

The PM peak is more congested in parts than the AM peak, particularly in Scenario 2 and 3.

Therefore it would be expected that the delay per vehicle is more than in the AM peak and the

average speed in the network less. Table 3.21 and 3.22 show the network speed and average

delay in the network.

Table 3.21: Average Car Speed (PM Peak)

Scenario Average Speed (kph)

1 31.6

2 21.8

3 25.7

Table 3.22: Average Delay per Vehicle (PM Peak)

Scenario Average Delay (minutes)

1 3.0

2 5.6

3 4.4

Scenario 1 shows that the network flows freely with an average network speed of 31.6 kph and a delay per vehicle of only 3 minutes. Scenario 2 and 3 highlight the congested nature of the network as the network speed is considerably slower, 21.8 kph and 25.7 kph for Scenario 2 and 3 respectively. The delay per vehicle is also more at 5.6 and 4.4 minutes for Scenario 2 and 3 respectively. Therefore the development trips do have an impact on the network performance, hindering the average speed and increasing delays in the network during the peak.

3.7 Summary of Network Results

The network results give a good indication of the performance of each scenario, in summary:

• Scenario 1 is heavily congested in 2021 as demonstrated by all indices;

• Scenario 2 makes this worse network wide but the mitigation measures improve

network performance in the vicinity of the AAP. However, the wider network is

particularly congested particularly along Longbridge Lane and the surrounding roads.

This has a major impact on the overall network performance as highlighted in this

chapter.

• Scenario 3, with the introduction of demand management improves the overall network

situation to typically within 10% of the performance of Scenario 1 in 2021. This is within

normally accepted day to day variations of traffic.

• The transportation and highway infrastructure measures, including demand

management proposals, generally mitigate the impact of the AAP but do not mitigate

the continued delays on the network that would result thorough background traffic

growth.

Sensitivity Option Testing


4.1 Introduction

This section discusses the sensitivity testing undertaken to provide a robust analysis of the

effect of the proposed AAP on the local network infrastructure. It is possible that if the AAP

development comes forward this could suppress the growth assumptions made for background

traffic growth in Scenario 1 given the constrained urban environment.

The sensitivity option test was also devised to demonstrate that the AAP infrastructure was not

mitigating against background traffic growth. This is further discussed in this section.

It was indicated in the previous chapter that a substantial amount of traffic was not able to enter

the network during the peak periods, particularly in the AM peak. In the development scenarios

this was occurring because of congestion at peripheral junctions associated with external to

external traffic growth, which would reduce the potential impact of the AAP on the local network.

In the absence of any detailed predictions from the PRISM model regarding growth in the area,

the use of TEMPRO growth plus the AAP development could over estimate potential growth on

the network. Therefore it was considered appropriate to develop sensitivity options that

considered reduced growth on the network (Table 4.1); designed to highlight further the impact

of the AAP infrastructure on the network. The two option tests correspond to Scenarios 2 and 3

discussed previously.

Table 4.1: Sensitivity Option Test Network and Traffic

Option Test Network Traffic

1 Proposed network

infrastructure and AAP

• 2006 background traffic.

• Development traffic with no mode shift.

2 Proposed network

infrastructure and AAP

• 2006 background traffic.


These sensitivity options, tested later in this chapter, have been compared to the Scenario 1

results set out earlier in this report. This is a crude assessment and is not necessarily a like for

like comparison which would normally be the case when assessing the impacts of

developments on the transport network. A more appropriate test would be to consider no

background traffic growth for Scenario 1, but with some Longbridge traffic added back into the

matrix assuming what development would take place in the AAP area without the benefit of

planning restrictions. The debate, however, over what could be developed on the site has not

come to a common agreement and as such the background growth assumed for Scenario 1

could be considered a proxy in this instance.

4.2 Matrix Development

The original scenario traffic levels assumed that there would be an increased travel demand

outside of the immediate area due to numerous interventions, like the Northfield Relief Road

and Queen Elizabeth Hospital. For this reason it was decided to growth the external to external

background traffic movements using TEMPRO version 5.0. This approach is expected to

provide the highest traffic level forecasts in the future year.

It has been debated that this approach forecasts too much traffic and that in the future year

there would be less background growth given the congested urban network in Birmingham.

4 Sensitivity Option Testing


Therefore it was decided to apply a different assumption for background growth which would

yield a lower future year traffic forecast. It was expected that this traffic forecast would mean

fewer vehicles are held up at peripheral junctions and would emphasise the impact of the AAP

development on the network.

The alternative approach assumes zero background growth in peak hour periods. Therefore

the background traffic levels in the future year would be the same as 2006. This assumption is

based on the experience of traffic patterns in Birmingham. The only growth is due to the

inclusion of development traffic. This approach resulted in the following traffic levels (Table 4.2

and 4.3):

Table 4.2: Sensitivity Option Test Matrix Totals for AM Peak

Matrix Option Test 1 Option Test 2

Background Traffic 8993 8993

Development Traffic with No Mode Shift 5648 -

Development Traffic with Mode Shift - 4891

Pass-By and Diverted Trips -571 -571

Cars Modelled 14070 13313

Heavies Modelled 152 152

Table 4.3: Sensitivity Option Test Matrix Totals for PM Peak

Matrix Option Test 1 Option Test 2

Background Traffic 9288 9288

Development Traffic with No Mode Shift 5307 -

Development Traffic with Mode Shift - 4728

Pass-By and Diverted Trips -678 -678

Cars Modelled 13917 13338

Heavies Modelled 41 41

4.3 Option Testing Development

There were no network alternations made to the models. The only alterations made were to

optimise the signal timings where appropriate (Table 4.4 and Table 4.5) because the traffic

flow pattern altered due to the reduced travel demand for external to externals trips. This was

to ensure the Option Tests were optimised. Any alterations made in Option Test 1 were

replicated in Option Test 2.

Table 4.4: Alterations made to the AM Peak Signal Timings

Option Test Interchanges altered in the AM Peak

Signal Control 6 A38 / West Works Link

Signal Control 8 Longbridge Lane / Park and Ride plus Development Site 1 and 2

Signal Control 10 A38 / Lickey Road Link

Table 4.5: Alterations made to the PM Peak Signal Timings

Option Test Interchanges altered in the PM Peak

Signal Control 1 A38 / Ashill Road

Signal Control 8 Longbridge Lane / Park and Ride plus Development Site

Signal Control 11 Longbridge Lane / Coombes Lane / Turves Green 1 and 2

Signal Control 15 Longbridge Lane / A441 Birmingham Road

4.4 Option Testing Results

The parameters used to assess the performance of the network in the option testing are the

same as the ones described in section 3.1:

• Held up Traffic;

• Queues;


• Journey Times through the Network;

• Average Network Speed;

• Average Delay per Vehicle.

4.4.1 Model Stability

The importance of model convergence to determine the model validity and reliability of the

results is discussed in section 2.3. Each sensitivity option test has a very high level of

convergence (Table 4.6) so the results can be seen as reliable and compared against each

other.

Table 4.6: Model Convergence

Option Test 1 Option Test 2

AM Peak PM Peak AM Peak PM Peak

99.89 99.79 99.87 99.78

4.5 Option Test 1 and 2 Network Performance

Traffic is held up in both peaks in the sensitivity option tests at the same locations as the 2021

assessments. In the AM peak the percentage of traffic held up out of the matrix is less than in

the respective Scenarios but more than Scenario 1. The locations of traffic held up are similar

to Scenario 1, 2 and 3. The traffic held up in the PM peak is negligible, although some traffic is

still unable to enter the network because of congestion (Table 4.7 and Table 4.8). Table 3.2 is

included in this section for comparison purposes.

Table 3.2: Number of Vehicles Unable to Enter the Network (Scenario 1)


Vehicles

Percentage of

Total Traffic (%)

3 West Heath Road 105


9 B4096 Old Birmingham Road 105 AM

20 Lickey Square 65

329 3.1

PM 5 A441 Birmingham Road southbound 176 347 3.2

Table 4.7: Number of Vehicles Unable to Enter the Network (Option Test 1)


Vehicles

Percentage of

Total Traffic (%)



20 Lickey Square 70 AM


647 4.6

PM 29 Park and Ride plus Development Site 11 11 0.1

Table 4.8: Number of Vehicles Unable to Enter the Network (Option Test 2)


Vehicles

Percentage of

Total Traffic (%)



20 Lickey Square 41 AM


296 2.2

PM 29 Park and Ride plus Development Site 4 4 0.03



The locations where traffic is held up are all external; none are in the AAP area (Figure 4.1).

Although, the traffic levels are lower than in the respective Scenarios, certain junctions and

roads have queuing traffic with the forecasted traffic demand. The junctions and roads with

queuing which cause a negative impact to the network are similar to the problems experienced

in Scenario 2 and 3, but on a lesser scale.

Longbridge Lane has queuing westbound from the Longbridge Lane / Groveley Lane / Cofton

Road interchange which impacts on the Longbridge Lane / A441 junction (Figure 4.2).

This highlights that certain junctions outside the immediate AAP area cannot cope with the

predicted traffic levels even if there is no traffic growth in the future, but the development is

built.

4.5.1.1 A441 Birmingham Road northbound

Traffic is unable to enter the network due to the insufficient capacity of the Hopwood

roundabout. Despite the roundabout being improved from its current configuration, the demand

is too heavy for the roundabout to cope. The demand has been reduced from Scenario 2 and 3

but it is still too much for the roundabout capacity.

4.5.1.2 B4096 Old Birmingham Road / Lickey Square

The Rose Hill roundabout has queuing in Scenario 1, so with no improvements made at this

roundabout, it is expected that traffic would queue, affecting the Old Birmingham Road and

Lickey Square traffic flow.

4.5.1.3 Cock Hill Lane

There was traffic held up at Cock Hill Lane because of the high volume of traffic that travels eastbound along the A38 Bristol Road. Although no traffic is held up at this location in Scenario 1, when the development traffic is included, it increases the number of trips from A38 Bristol Road West which hinders traffic exiting Cock Hill Lane. The percentage of vehicles held up has reduced by approximately 30% at this location from Scenario 2 and 3 respectively.


Although there is only one location where traffic is unable to enter the network (Figure 4.3),

certain roads in the network cause considerable congestion which do have a wider network

impact. Longbridge Lane is a considerable problem because of the two signal interchanges:

• Longbridge Lane / Coombes Lane / Turves Green;

• Longbridge Lane / Groveley Lane / Cofton Road.

Traffic queues back from the Longbridge Lane / Coombes Lane / Turves Green interchange to

the Park and Ride plus Development site restricting traffic from exiting the site. As a result of

more traffic entering onto Longbridge Lane from the sites north and south of Longbridge Lane

the interchanges and Longbridge Lane cannot cope, causing queuing (Figure 4.4).

The Longbridge Lane / Groveley Lane / Cofton Road interchange has traffic queuing along all

four arms particularly along Longbridge Lane, which affects the Longbridge Lane / A441

interchange causing queuing along the A441.


4.5.2.1 Park and Ride plus Development Site

Traffic is held up because of queuing traffic along Longbridge Lane and not the junction signal timings. Queuing traffic along Longbridge Lane from the Longbridge Lane / Coombes Lane / Turves Green interchange to the Park and Ride interchange hinders traffic exiting the site. The number of vehicles unable to access the network is negligible, only 11 vehicles and 4 vehicles in Option Test 2 and 3 respectively (Table 4.7 and 4.8).

4.6 Network Indicators – Journey Times

The network performance based on journey times through key strategic routes is discussed in

section 3.5.

4.6.1 AM Peak Journey Times

The journey times in minutes between each selected OD pair for the two option tests are shown in Table 4.9 and 4.10. The total journey time through the key strategic routes is shown in Table 4.11. Scenario 1 has been included in Table 3.5 to allow for comparison between the models.



Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 10.97 9.79 5.67 4.26

A441 Redditch

Road 15.12 0.00 7.64 15.57 18.77

Hopwood

Roundabout 11.45 3.45 0.00 0.00 0.00

Rose Hill

Roundabout 15.77 23.20 0.00 0.00 0.00

A38 Bristol

Road West 4.97 16.94 0.00 5.60 0.00

Table 4.9: Average Car Journey Time (AM Peak) for Option Test 1


To Location

From Location

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 7.65 8.19 5.37 5.26

A441 Redditch

Road 15.93 0.00 8.93 14.97 17.69

Hopwood

Roundabout 11.09 5.03 0.00 0.00 0.00

Rose Hill

Roundabout 20.30 22.07 0.00 0.00 0.00

A38 Bristol

Road West 3.97 10.20 0.00 7.19 0.00


Table 4.10: Average Car Journey Time (AM Peak) for Option Test 2


To Location

From Location

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 7.13 7.95 6.00 4.93

A441 Redditch

Road 10.62 0.00 5.22 12.15 13.19

Hopwood

Roundabout 11.85 6.77 0.00 0.00 0.00

Rose Hill

Roundabout 18.10 21.21 0.00 0.00 0.00

A38 Bristol

Road West 3.85 9.47 0.00 6.70 0.00

Table 4.11: Total Journey Time through the Key Strategic Routes (AM Peak)

Model Journey Time (minutes)

Scenario 1 169.2

Option Test 2 163.8

Option Test 3 145.1

The difference in journey time and percentage change between Option Test 1 and 2 against

Scenario 1 in the AM peak is shown in Table 4.12 and 4.13. A negative number means the

Option Test is faster for that OD pair; percentage change is in brackets. The total journey time

difference is in Table 4.14.

Table 4.12: AM Peak Journey Time Difference for Option Test 1 compared to Scenario 1


To Location

From Location A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 -3.32 (-30.3) -1.60 (-16.3) -0.30 (-5.3) 1.00 (23.5)

A441 Redditch

Road 0.81 (5.3) 0.00 1.29 (16.8) -0.61 (-3.9) -1.08 (-5.8)

Hopwood

Roundabout -0.37 (-3.2) 1.59 (46.1) 0.00 0.00 0.00

Rose Hill

Roundabout 4.53 (28.7) -1.13 (-4.8) 0.00 0.00 0.00

A38 Bristol

Road West -0.99 (-20.0) -6.74 (-39.8) 0.00 1.60 (28.5) 0.00


Table 4.13: AM Peak Journey Time Difference for Option Test 2 compared to Scenario 1


To Location


Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 -3.84 (-35.0) -1.84 (-18.8) 0.33 (5.8) 0.66 (15.6)

A441 Redditch

Road -4.50 (-29.7) 0.00 -2.43 (-31.8) -3.42 (-22.0) -5.58 (-29.7)

Hopwood

Roundabout 0.40 (3.5) 3.32 (96.5) 0.00 0.00 0.00

Rose Hill

Roundabout 2.33 (14.8) -1.99 (-8.6) 0.00 0.00 0.00

A38 Bristol

Road West -1.12 (-22.6) -7.47 (-44.1) 0.00 1.10 (19.6) 0.00

The bold figures in the above tables indicate where there is a significant change in journey time

according to the criteria defined in section 3.5. Table 4.14: Total Journey Time Difference through the Key Strategic Routes (AM Peak)

Model Comparison Journey Time Difference (minutes) Percentage Change (%)

Option Test 1 compared to

Scenario 1 - 5.4 - 3.5


Scenario 1 - 24.1 - 14

4.6.2 PM Peak Journey Times

The journey times in minutes between each selected OD pair for the two option tests is shown

in Table 4.15 and 4.16. Table 4.17 shows the total journey time for the Option Tests and

Scenario 1. Table 3.12 is included in this chapter for comparison purposes.



Location To

Location From

A38 Bristol

Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 5.59 10.14 5.81 4.21

A441 Redditch

Road 21.52 0.00 13.20 23.34 23.42

Hopwood

Roundabout 11.77 3.12 0.00 0.00 0.00

Rose Hill

Roundabout 8.44 12.43 0.00 0.00 9.14

A38 Bristol

Road West 3.78 9.21 13.52 6.48 0.00


Table 4.15: Average Car Journey Time (PM Peak) for Option Test 1


To Location


Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 10.99 12.86 7.41 5.72

A441 Redditch

Road 13.64 0.00 5.01 15.08 16.98

Hopwood

Roundabout 12.45 4.58 0.00 0.00 0.00

Rose Hill

Roundabout 6.61 14.93 0.00 0.00 8.21

A38 Bristol

Road West 4.62 16.63 17.80 9.76 0.00

Table 4.16: Average Car Journey Time (PM Peak) for Option Test 2


To Location


Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 11.25 13.80 7.13 4.87

A441 Redditch

Road 11.65 0.00 6.31 13.76 14.65

Hopwood

Roundabout 10.51 4.31 0.00 0.00 0.00

Rose Hill

Roundabout 6.26 13.72 0.00 0.00 8.79

A38 Bristol

Road West 4.69 16.60 18.21 9.19 0.00

Table 4.17: Total Journey Time through the Key Strategic Routes (PM Peak)

Model Journey Time (minutes)

Scenario 1 185.1

Option Test 2 183.3

Option Test 2 175.7

The difference in journey time and percentage change for Option Test 1 and 2 compared to

Scenario 1 in the PM peak is shown in Table 4.18 and 4.19. A negative number means the

Option Test is faster for that OD pair. The total journey time difference and percent change is

shown in Table 4.20.


Table 4.18: PM Peak Journey Time Difference for Option Test 1 compared to Scenario 1


To Location


Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 5.41 (96.7) 2.72 (26.8) 1.60 (27.6) 1.51 (35.9)

A441 Redditch

Road -7.88 (-36.6) 0.00 -8.19 (-62.0) -8.26 (-35.4) -6.44 (-27.5)

Hopwood

Roundabout 0.68 (5.8) 1.46 (46.9) 0.00 0.00 0.00

Rose Hill

Roundabout -1.84 (-21.8) 2.50 (20.1) 0.00 0.00 -0.92 (-10.1)

A38 Bristol

Road West 0.84 (22.3) 7.41 (80.4) 4.28 (31.7) 3.28 (50.6) 0.00

Table 4.19: PM Peak Journey Time Difference for Option Test 2 compared to Scenario 1


To Location


Road East

A441

Redditch

Road

Hopwood

Roundabout

Rose Hill

Roundabout

A38 Bristol

Road West

A38 Bristol

Road East 0.00 5.67 (101.4) 3.65 (36.0) 1.32 (22.7) 0.66 (15.8)

A441 Redditch

Road -9.87 (-45.8) 0.00 -6.89 (-52.2) -9.59 (-41.1) -8.77 (-37.5)

Hopwood

Roundabout -1.26 (-10.7) 1.19 (38.3) 0.00 0.00 0.00

Rose Hill

Roundabout -2.18 (-25.9) 1.30 (10.4) 0.00 0.00 -0.35 (-3.8)

A38 Bristol

Road West 0.91 (24.2) 7.39 (80.2) 4.70 (34.8) 2.71 (41.8) 0.00

The bold figures in the tables above indicate where there is a significant change in journey time

according to the criteria defined in section 3.5.

Table 4.20: Total Journey Time Difference through the Key Strategic Routes (AM Peak)

Model Comparison Journey Time Difference (minutes) Percentage Change (%)


Scenario 1 - 1.8 - 1


Scenario 2 - 9.4 - 5.4

4.6.3 Journey Time Summary

Option Test 1 and 2 have a positive impact on the network compared against Scenario 1.

There is an overall decrease in total journey time along the key strategic routes in both model

peaks. Therefore when the external to external background traffic is not included, the impact of

the AAP and extra trips are mitigated by the proposed infrastructure.

Certain routes do still show a slower journey time, particularly in the PM peak to A441 Redditch

Road. As discussed in section 3.5.3, Longbridge Lane during heavily congested peak periods

is still a problem.


4.7 Network Indicators – Average Speed and Delay

The importance of average speed and delay to show the network performance is discussed in section 3.6.

4.7.1 AM Peak

In the AM peak the average car speed through the network for Option Test 1 and 2 is faster

than Scenario 1. Table 4.21 shows the average car speed. In Scenario 2 the car speed is over

3 kph faster than Scenario 1, which means the mitigation measures are successful in reducing

the impact of the development when there is no external background growth in the network.

The delays per vehicle are also less for both option tests compared to Scenario 1, by almost a

minute (0.9 minutes) for Option Test 2 (Table 4.22).

Table 4.21: Average Car Speed (AM Peak)

Model Average Speed (kph)

Scenario 1 27.5

Option Test 1 27.9

Option Test 2 30.7

Table 4.22: Average Delay per Vehicle (AM Peak)

Model Average Delay (minutes)

Scenario 1 4.0

Option Test 1 3.8

Option Test 2 3.1

4.7.2 PM Peak

The PM peak results for the two option tests show a slower average network speed than

Scenario 1 (Table 4.23). This follows the same trend as the scenario testing; when the

development trips are included the network speed is slower in this peak. Therefore when the

traffic can get into the network, the increased trips do have a negative impact on the network

performance. The delay experienced per vehicle is also more than in Scenario 1, 3.9 and 3.2

minutes for Option Test 1 and 2 respectively (Table 4.24).

Table 4.23: Average Car Speed (PM Peak)

Model Average Speed (kph)

Scenario 1 31.6

Option Test 1 27.1

Option Test 2 30.0

Table 4.24: Average Delay per Vehicle (PM Peak)

Model Average Delay (minutes)

Scenario 1 3.0

Option Test 1 3.9

Option Test 2 3.2

These results highlight that the network is congested during the peak. Particular roads and

junctions require improvements in order to mitigate fully the impact of the PM peak.


4.8 Summary of Sensitivity Option Testing Results

The sensitivity option tests results display a positive network performance compared to

Scenario 1, in summary:

• Option Test 1 has reduced congestion in the network; highlighted by the reduction in

journey time along key strategic routes. Despite the reduction along the key routes, the

wider network in the PM peak is worse due to congestion on Longbridge Lane and the

surrounding roads.

• Option Test 2 improves further the key strategic route journey times in both peaks and

network-wide performance in the AM peak. The wider-network performance, speed

and delay in the PM peak, despite the introduction of demand management is worse

than Scenario 1. The overall network performance in the PM peak is also worse due to

the effect of the wider-network roads.

Strategic Road Network


5.1 Introduction

This section sets out the analysis of the strategic highway network and the impact of the AAP

development proposals. It was agreed at the outset of the study, that a robust analytical traffic

modelling platform would be required in order to test and assess the impact of proposals put

forward by the Longbridge Area Action Plan on the strategic road network.

Faber Maunsell’s approach to model development is founded on the application of a micro-

simulation model. This type of tool has the ability to examine the impacts of road closures,

junction modifications, bus priority and revised traffic circulation arrangements in detail. It is also

considered that the visual ‘front-end’ of VISSIM can be used to assist public consultation and

presentation phases of the work at a later date.

It has been agreed with the stakeholders (BCC, Worcestershire County Council and the

Highways Agency) that isolated VISSIM models would be the most appropriate way to model

the impacts on the Strategic Road Network (SRN).

This section considered the junctions in the following order:

• M42 Junction 1;

• M42 Junction 2;

• M5 Junction 4.

5.2 Model Development

A Local Model Validation Report (LMVR) has been developed which set out the development

and validation of micro-simulation traffic models (VISSIM) to support the development of the

Longbridge Area Action Plan (AAP). The development of the model has been carried out in

accordance with the ‘Design Manual for Roads and Bridges Volume 12a Section 4’ (DMRB),

and Interim Advice Note 26-01, “The Use and Application of Micro-simulation models”.

JMP, as agents to the Highways Agency, reviewed the models and the LMVR.

The development of the base models, as described in detail in the LMVR, included the following

key stages:

• Identification of the model area/coverage;

• Development and identification of model zone system;

• Highway network development;

• Demand matrix development;

• Model assignment;

• Model calibration and validation.

5.2.1 Model Periods

The three key junctions currently experience high volumes of traffic, which result in congestion

and delays across the highway network. The DMRB recommends that ‘in congested urban

areas the variation of travel times and costs throughout the day is complex. When modelling

these areas it is usually necessary to break the day down into separate periods covering AM,

PM and inter-peak periods for weekdays’. The following two periods have therefore been

developed in the model platform in order to represent observed periods of distinctly different

traffic conditions:

• AM Period (0800-0900);

• PM Period (1700-1800).

5 Strategic Road Network


The inter-peak period has not been incorporated into the modelling due to the nature of the

congestion. Each junction receives a high level of traffic throughout the day; however

congestion is not considered a constant problem. The models have therefore been developed

to deal with the network at extreme capacity which is during the AM and PM peak periods.

In line with DMRB, care has been taken to ensure the model periods cover the whole of each

period, not just the busiest hour. The two model periods are run with a 15 minute preload which

enables a representative level of traffic to ‘warm up’ the network before data is collected during

the designated periods.

5.2.2 Network Development

The three networks have been developed in VISSIM, through on-screen editing, based on

agreed model areas, suitable zone systems, site visit inventories and traffic signal data. This

stage is described in detail in the LMVR.

The development of the base model networks has been undertaken using an Ordnance Survey

(OS) map base over which the geometry and alignment of the networks have been constructed.

5.2.3 Survey Data Collection

A data collection exercise was undertaken at each junction in 2006. This was established as the

base year.

The following data was collected and an indication of what each value was used for in the

modelling process is given:

• Queue lengths (calibration);

• HA link counts from the TRADS database (calibration);

• Traffic turning counts (calibration and validation);

• Journey time measurements (validation);

• This data formed a base for building the matrices, calibration and validation.

5.2.4 Travel Demand

The VISSIM models have been developed using a dynamic (i.e. matrix based) assignment

technique. Dynamic assignment provides the ability for the model to calculate route choices

from origins to destinations through a minimum cost route assignment. A dynamic assignment

was selected over a static ‘fixed path’ model, as the junctions consist of numerous lane

changing characteristics that are best replicated by the resulting forward thinking route choice.

5.2.5 Model Calibration and Validation

Having prepared the necessary network and matrix data for the base models, the models were

subjected to an iterative process of calibration and validation. This was carried out in

accordance with the DMRB guidance. Further details can be found in the LMVR.

A number of further checks were made of the developed networks and matrices through an

independent audit of the traffic model carried out by JMP on behalf of the Highways Agency,

who concluded the model fit for purpose.

5.3 Existing Operation

The existing junctions were all validated as can be seen in the Local Model Validation Report (Appendix C). The M42 J2 and M5 J4 were validated to a base year of 2005 and M42 J1 to


2006. The matrices used for these junctions in the existing year operation are in Appendix B. The journey time for the existing junction operations are summarised in Table 5.1, 5.2 and 5.3. Table 5.1: M42 Junction 1 Existing Operation Journey Times (in seconds) (2006)

Movement 2006 – Existing Operation

From To AM PM

1 M42 Westbound Off-slip B4096 (S) 70.8 84.5

2 M42 Westbound Off-slip A38 (S) 86.9 80.2

3 M42 Westbound Off-slip A38 (N) 88.1 85

4 M42 Westbound Off-slip B4096(N) 138.6 111.7

5 A38 (S) A38 (N) 20.7 19.1

6 A38 (S) B4096 (N) 35.4 31.1

7 A38 (S) M42 Entry Slip 65.1 66.6

8 A38 (S) B4096 (S) 65.2 62.3

9 A38 (N) B4096 (N) 9.6 13.7

10 A38 (N) M42 Entry Slip 33.1 38

11 A38 (N) B4096 (S) 35.9 44.7

12 A38 (N) A38 (S) 75.9 84.3

13 B4096 (S) A38 (S) 14 10.1

14 B4096 (S) A38 (N) 27.7 16.8

15 B4096 (S) B4096 (N) 30.9 19.5

16 B4096 (S) M42 Entry Slip 67.2 56

17 B4096 (N) M42 Entry Slip 9.1 12.2

18 B4096 (N) B4096 (S) 12.5 16.6

19 B4096 (N) A38 (S) 25.2 30.7

20 B4096 (N) A38 (N) 28.9 36.4

Total Journey Time (minutes) 15.7 15.3

Traffic in Matrix 11711 11716

Total Traffic Held Back 1 0

Table 5.2: M42 Junction 2 Existing Operation Journey Times (in seconds) (2005)


From To AM PM

A441 North Service Station 19.5 22.6

A441 North M5 Eastbound (On Slip) 16.6 20.1

A441 North A441 South 39 41.6

A441 North M5 Westbound (On Slip) 41.8 45.6

A441 North A441 North (U Turn) 0 0

Service Station M5 Eastbound 8 7.7

Service Station A441 South 29.3 39.4

Service Station M5 Westbound 39.6 47

Service Station A441 North 62.7 61.6

Service Station Service Station 0 0

M5 Westbound (Off-slip) A441 South 112.6 36.7

M5 Westbound (Off-slip) M5 Westbound 0 0

M5 Westbound (Off-slip) A441 North 176.9 60.7

M5 Westbound (Off-slip) Service Station 168.5 64.2

M5 Westbound (Off-slip) M5 Eastbound (On Slip) 0 0

A441 South M5 Westbound 22.3 17.9

A441 South A441 North 52.5 34.6

A441 South Service Station 49.2 37.5

A441 South M5 Eastbound (On Slip) 46.1 39.4

A441 South A441 South 0 0


M5 Eastbound (Off-slip) A441 North 33.9 61.7

M5 Eastbound (Off-slip) Service Station 45.6 82.5

M5 Eastbound (Off-slip) M5 Eastbound (On Slip) 0 0

M5 Eastbound (Off-slip) A441 South 60.3 101.9

M5 Eastbound (Off-slip) M5 Westbound (On Slip) 0 0

M5 Eastbound Under Junction 11 11

M5 Westbound Under Junction 11.4 10.9

Total Journey Time (Minutes) 17.4 14.1



Table 5.3: M5 Junction 4 Existing Operation Journey Times (in seconds) (2005)


From To AM PM

1 M5 Sbound Off-slip A38 N 53.2 38.2

2 M5 Sbound Off-slip A38 S 56.8 43

3 M5 Sbound Off-slip M5 South 0 0

4 M5 Sbound Off-slip A491 96.4 83.6

5 M5 Sbound Off-slip M5 North 0 0

6 A38 N A38 S 49.1 43.1

7 A38 N M5 South 45 37.9

8 A38 N A491 77.3 60.8

9 A38 N M5 North 87.2 74.4

10 A38 N A38 N 0 0

11 A38 S M5 South 41.2 31.7

12 A38 S A491 54.9 50.3

13 A38 S M5 North 86.1 65.5

14 A38 S A38 N 91.7 91.1

15 A38 S A38 S 0 0

16 M5 Nbound Off-slip A491 44.9 108.4

17 M5 Nbound Off-slip M5 North 0 0

18 M5 Nbound Off-slip A38 N 92.9 124.1

19 M5 Nbound Off-slip A38 S 120.1 144.9

20 M5 Nbound Off-slip M5 South 0 0

21 A491 M5 North 44.2 81.6

22 A491 A38 N 58.9 89.7

23 A491 A38 S 79.9 115.9

24 A491 M5 South 89.4 114

25 A491 A492 0 0

26 M5 Northbound Under Junction 7.1 7.2

27 M5 Southbound Under Junction 7.3 7.3

Total Journey Time (Minutes) 21.4 23.5



5.4 Future Traffic Flows

The operation of the junctions has been assessed using three sets of traffic flows;

• 2021 Do minimum (background growth only);

• 2021 Longbridge AAP Development Traffic;

• 2021 Longbridge AAP Development Traffic with mode shift.


The methodology adopted to identify future year traffic flows is set out as follows:

• Apply TEMPRO version 5.0 (for the local roads) and NRTF (for the mainline motorway

flows) to the existing flows from 2005 and 2006 to obtain 2021 base flows;

• Develop matrices for development related traffic using the outputs of the Travel

Demand Model (TDM Report, Faber Maunsell, March 2008).

TEMPRO was used for the local roads growth because it allows trip projection in travel demand

at a local level compared to the NRTF which is national average growth. The growth rates

adopted are set out in Table 5.4. The matrices with the new weighted traffic levels using the

above methodology can be seen in Appendix B. Table 5.4: Growth Rates Applied

AM Peak PM Peak Junction

TEMPRO NRTF TEMPRO NRTF

M42 J1 1.164 1.231 1.166 1.231

M42 J2 1.205 1.252 1.176 1.252

M5 J4 1.304 1.252 1.296 1.252

5.5 Model Stability

The nature of dynamic assignment and model stability is discussed in section 3.2. All the models were dynamic and had a 100% level of convergence. Therefore the models are all stable and provide reliable results which can be compared.

5.6 M42 Junction 1 The operation of the M42 Junction 1 in both the morning and evening peak for the 2005 validated base model was similar in both peaks, with small amounts of congestion occurring in both periods. Queues occurred along the Birmingham Road (A38) south and Birmingham Road (A38) north. Both models also had extensive queues on the B4096 south. However, all vehicles were able to enter the network. Six future year models were run with 2021 future year growth on the same junction layout as the base year. These models are:

• AM do minimum (background growth only)

• AM background growth with development trips

• AM background growth, development trips and mode shift

• PM do minimum (background growth only)

• PM background growth with development trips

• PM background growth, development trips and mode shift

For each scenario, adjustments have been made to the VISSIM network as follows:

• the signal timings have been reviewed and adjusted to achieve optimal traffic throughput for each scenario

• lane use has been reviewed to ensure that the roundabout is operating efficiently under more heavily trafficked conditions

• driver behaviour, again to represent any changes in driver behaviours as a result of more heavily trafficked conditions.

5.6.1 2021 AM Peak - Do Minimum The do minimum scenario in the AM peak model as expected brings more congestion to the junction than in the 2005 base year. Queues on the M5 off-slip do not cause tailbacks on the M5. Optimisation of traffic signals has enabled the gyratory to remain free from congestion (Figure 5.1).


Figure 5.1: 2021 AM Peak (M42 J1) Do Minimum 08:50

5.6.2 2021 AM peak – Background Growth & Development Trips The addition of the development trips generated from the Longbridge site adds further traffic to the network. The traffic flows, as expected, brings more congestion to the junction than in the 2021 base year. Queues on the M5 off-slip do not cause tailbacks on the M5. Optimisation of traffic signals has enabled the gyratory to remain free from congestion (Figure 5.2). Figure 5.2: 2021 AM Peak (M42 J1) No Mode Shift 08:50


5.6.3 2021 AM Peak Background Growth, Development Trips & Mode Shift

When the mode shift assumptions are applied to the future traffic demand, there is little change to the junction operation as compared to the development trip scenario (without mode shift) mainly because mode shift only reduces the matrices by approximately 50 trips. The only notable improvement with ‘mode shift’ is that fewer vehicles are held up at the end of the peak hour.

5.6.4 2021 PM Peak Do Minimum

The do minimum scenario in the PM peak model, as expected brings more congestion to the junction than in the 2005 base year. The A38 is busy in both directions throughout the peak and B4096 (N) is fairly congested (Figure 5.3). Figure 5.3: 2021 Base (M42 J1) Do Minimum 17:55

5.6.5 2021 PM Peak Background Growth & Development Trips

The 2021 evening peak with the addition of development trips, shows an increased amount of queuing and congestion on the network (Figure 5.4).


Figure 5.4: 2021 Base (M42 J1) No Mode Shift 17:55

5.6.6 2021 PM Peak Background Growth, Development Trips & Mode Shift

The mode shift assumptions make little difference to the congested network, as it only removes 48 trips from the network through mode shift. Queuing and operation is almost identical to the background growth and development trips with out mode shift assumptions. The only noticeable improvement in the results is that fewer vehicles are held up off the network at the end of the modelled period and there are slight decreases in the journey times across the network.

5.6.7 Comparison of Scenarios Inspection of the VISSIM models for each scenario shows the following:

• Generally, the signals do not block traffic back in both the morning and evening peak

hours;

• The merge on the A38 southbound causes some queuing, particularly in the evening

peak hour with the addition of the development related traffic. These queues have an

impact on the operation by backing up onto the gyratory disrupting the flow. However,

there is no blocking back to the mainline flow on the motorway;

• Queues do not extend to the mainline flows on the motorway in both the morning peak

and evening peak hours;

• Queuing is generally very similar between 2021 base and 2021 base plus development

in both the morning and evening peak hours. However the increased traffic causes

longer queues on the A38 (N) arm in the morning peak.

Journey times have been extracted from each of the model to provide an indicator of junction

operation. These results are summarised in Table 5.5. Table 5.6 summarises the average

journey times for each approach arm.


Table 5.5: M42 Junction 1 Average Journey Time (in seconds)

Movement 2021 – Do Minimum 2021 Base + Dev – Without Mode Shift

2021 Base + Dev – With Mode Shift

From To AM PM AM PM AM PM

1

M42 Westbound Off-slip B4096 (S) 45.3 78.4 61.3 82.7 63 83.2

2

M42 Westbound Off-slip A38 (S) 49.9 77.9 67 88.6 65 85.7

3

M42 Westbound Off-slip A38 (N) 66.3 87.8 73.9 90.3 75.2 93.7

4

M42 Westbound Off-slip B4096(N) 84.3 102 85.7 108.4 92.3 104.3

5 A38 (S) A38 (N) 37 31 38.2 29.1 36.4 29.2

6 A38 (S) B4096 (N) 38 30.9 37.9 29.8 39.2 28.8

7 A38 (S) M42 Entry Slip 51.1 68.7 78.9 75.9 71.5 66.1

8 A38 (S) B4096 (S) 4.1 3.8 4.1 3.4 4 3.5

9 A38 (N) B4096 (N) 9.1 10.8 9.8 11.1 9 9.9

10 A38 (N) M42 Entry Slip 27 50.1 39.6 57.5 34.2 48.1

11 A38 (N) B4096 (S) 31.8 52.8 45.8 60.8 40.1 50.7

12 A38 (N) A38 (S) 12.4 9.8 12.5 9.7 13.3 10

13 B4096 (S) A38 (S) 21 24.8 21.7 21.3 19.8 28

14 B4096 (S) A38 (N) 35.7 51.5 39.2 48.1 39.1 50.8

15 B4096 (S) B4096 (N) 54.7 66.1 50.4 78.6 66.5 81.6

16 B4096 (S) M42 Entry Slip 61.6 76.8 65 71.5 66.6 73.4

17 B4096 (N) M42 Entry Slip 11.8 7.4 15.2 8.9 15 9.6

18 B4096 (N) B4096 (S) 39.4 50.8 45.1 54 44.6 50.5

19 B4096 (N) A38 (S) 39.9 49.7 52.5 58.7 47.5 49.1

20 B4096 (N) A38 (N) 86.9 67.8 88.4 73.1 93.3 65.7

Total Journey Time (In Minutes) 13.5 16.6 15.5 17.7 15.6 17.0

Traffic in Matrix 14198 14180 14458 14416 14402 14373

Traffic Held Back on M42 WB 7 14 7 14 7 14

Traffic Held Back on A38 (N) - - 87 37 44 2

Traffic Held Back on B4096 (N) - - - - - 9

Table 5.6: Summary of Average Journey Times by Approach (in seconds)

AM peak PM Peak

2021

Base flows

2021

With

development

no mode

shift,

2021 with

development

with mode

shift,

2021

Base flows

2021

With

development

no mode

shift

2021 with

development

with mode

shift

M42 WB 245.8 287.9 295.5 346.1 370 366.9

A38 S 138.5 167.5 160.4 140.4 144.5 134.1

A38 N 72 99.3 87.3 117.5 132.8 112.2

B4096 S 173 176.3 192 219.2 219.5 233.8

B4096 N 178 201.2 200.4 175.7 194.7 174.9

Total journey

time (mins) 13.5 15.5 15.6 16.6 17.7 17.0

Total Traffic

Held Back 7 94 51 14 51 25


Analysis of these results shows that:

• There is a slight deterioration in journey times in the morning peak hour with the

proposed development compared to the 2021 base on all approaches. However, the

overall change is 13.5 minutes in 2021 base compared to 15.5 minutes with the

proposed development and no mode shift;

• There is an increase in traffic held up in the morning peak hour from 7 vehicles in the

base compared to 94 vehicles with the proposed development (no mode shift) and 51

vehicles with mode shift;

• In the evening peak hour, there is a slight deterioration in journey time with no mode

shift on all approaches. However, this is considered to be imperceptible.

• There is an improvement in journey times from A38 south, A38 north and B4096 north

in the evening peak hour with mode shift;

• There is a slight increase in traffic held up in the evening peak hour with the proposed

development (51 vehicles with no mode shift and 25 vehicles with mode shift) and the

improvements compared to the 2021 base (14 vehicles).

It is therefore concluded that the proposed development will not have an adverse impact on the

overall operation of the junction. Notwithstanding this, it is proposed to provide a contribution to

address residual impacts on specific arms and movements through the junction. MOVA (Microprocessor Optimised Vehicle Actuation) is a method of controlling traffic signals at junctions. It is a well established strategy for the control of traffic light signals at isolated junctions. It is the required signal control method for new junctions on the trunk road network that are not normally part of a linked network. MOVA is particularly well suited to the following conditions:


• Sites experiencing capacity difficulties under Vehicle Actuation (VA) control with congestion on one or more approaches.


• Where more than one junction is situated too close to be considered as isolated, there are ways in which two or more junctions can be linked by the use of MOVA control. Partially or even fully signalised roundabouts are a good example of a MOVA linking opportunity.

MOVA is generally accepted as the best option for signalled roundabouts and will generally provide in the region of 20% reduction in delays. A TRL research project found that an average 13% decrease in delay at 20 junctions running with MOVA compared with standard VA. This is based on the TRL study "RR279 MOVA: The 20-site trial” by J R Peirce and P J Webb. 1990".

5.7 M42 Junction 2

5.7.1 Existing Year Summary The operation of the M42 junction 2 in both the morning and evening peak for the 2005 validated base model was similar in both peaks with small amounts of congestion occurring in both periods. Queues occur on the M42 westbound off-slip, on average 10 – 15 vehicles over the latter half of the peak hour in the PM peak, however this queue is not generally considered extensive. Small adjustments were made to the signal timings to achieve the optimum traffic throughput. For each future year scenario, adjustments have been made to the VISSIM network as follows:

• the signal timings have been reviewed and adjusted to achieve optimal traffic throughput for each scenario;

• lane use has been reviewed to ensure that the roundabout is operating efficiently under more heavily trafficked conditions;

• driver behaviour, again to represent any changes in driver behaviours as a result of more heavily trafficked conditions.


5.7.1.1 2021 AM Peak Do Minimum

The junction is shown to operate within capacity, with few queues on any of the entry arms, although the M42 east and westbound carriageways are busier (Figure 5.5). Figure 5.5: 2021 AM Peak (M42 J2) Do Minimum 08:50

5.7.2 2021 AM Peak Background Growth & Development Trips

There is little queuing between the signals on the roundabout. The junction is seen to operate similar to the do minimum scenario (Figure 5.6). Figure 5.6: 2021 AM Peak (M42 J2) No Mode Shift 08:50


The mode-shift assumptions remove 41 trips from the matrix. Even with this reduction in vehicles at this junction, the model operates in much the same way as the 2021 base and development without mode shift network.



There is little queuing between the signals on the roundabout. There are no queues from the motorway slip roads back to the main motorway flow (Figure 5.7). Figure 5.7: 2021 PM Peak (M42 J2) Do Minimum 17:50


In 2021 without mode shift, the network operates in a very similar way to the base 2021 do minimum network (Figure 5.8). Figure 5.8: 2021 PM Peak (M42 J2) No Mode Shift 17:50

5.7.6 2021 PM Peak Background Growth, Development Trips & Mode Shift The mode shift assumptions remove 18 trips from the matrix at this junction and as such the impact of the reduction in traffic is negligible. Essentially the network operates identically to the background growth plus development without mode shift scenario.


5.7.7 Comparison

Inspection of the VISSIM models for each scenario shows the following:

• Generally, the signals do not cause blocking back in both the morning and evening

peak hours.

• There are some transient queues on the off-slips but these do not extend to the

mainline flows on the motorway in both the morning peak and evening peak hours.


in both the morning and evening peak hours. Journey times have been extracted from each of the model to provide an indicator of junction operation. These results are summarised in Table 5.7. Table 5.7: M42 Junction 2 Journey Times

2021 – Do Minimum 2021 Base + Dev – Without Mode Shift

2021 Base + Dev – With Mode Shift


A441 North Service Station 21.5 19.4 32 27.6 29.5 30

A441 North M5 Eastbound

(On Slip) 23.6 19.7 31.4 26.8 29.2 27.1

A441 North A441 South 50.7 45.9 59.2 55.9 56.3 56.3

A441 North M5 Westbound

(On Slip) 62.3 54.7 67.4 69.1 68.4 67.7

A441 North A441 North

(U Turn) 0 0 0 0 0 0

Service Station M5 Eastbound 7.2 7.3 7.2 7.8 7.2 7.4

Service Station A441 South 48.8 37.2 49.6 51 51.6 52.5

Service Station M5 Westbound 55.2 49.8 58.7 60.1 57.7 60.1

Service Station A441 North 74.1 67.4 71.7 78.8 71 75.2

Service Station Service Station 0 0 0 0 0 0

M5 Westbound (Off-slip)

A441 South 28.1 36.6 31.3 44.2 31.1 42.2


M5 Westbound 0 0 0 0 0 0


A441 North 50.5 67.2 59.8 77.9 59.7 73.6


Service Station 55 70.1 58.4 75.8 61.1 73.3


M5 Eastbound (On Slip)

0 0 0 0 0 0

A441 South M5 Westbound 21.1 23.9 31 26.1 30.3 25.2

A441 South A441 North 36.9 45.9 61.6 54.5 55.7 51

A441 South Service Station 43.4 49.1 66.3 59.1 60.7 53.1

A441 South M5 Eastbound

(On Slip) 42.4 47.2 65.3 57.5 60.1 53.5

A441 South A441 South 0 0 0 0 0 0

M5 Eastbound (Off-slip)

A441 North 38.7 42.7 43.1 43.8 41 43.2


Service Station 50.6 47.9 55.6 48.9 52.6 47.7


M5 Eastbound (On Slip)

0 0 0 0 0 0


A441 South 72.1 64.8 74.4 66.2 72.2 65.9


M5 Westbound (On Slip)

0 0 0 0 0 0

M5 Eastbound Under Junction 11.2 11 12.1 11.1 13.8 11

M5 Westbound Under Junction 10.9 11.1 11.1 11.2 11.1 11.2

Total Journey Time (Minutes) 13.4 13.6 15.8 15.9 15.3 15.5



Traffic Held Back on M42 WB - 8 1 61 - 111

Traffic Held Back on M42 EB 1 - 1 - 1 -

Table 5.8 shows a summary of the average journey times for each approach arm. Table 5.8 Summary of Average Journey Times by Approach (in seconds)

AM Peak PM Peak

2021

Base

flows,

existing

layout

2021

With

development

no mode

shift,

proposed

layout

2021 with

development

with mode

shift, proposed

layout

2021

Base

flows,

existing

layout

2021

With

developme

nt no mode

shift,

proposed

layout

2021 with

development

with mode

shift,

proposed

layout

A441 N 158.1 190 183.4 139.7 179.4 181.1

Service Station 185.3 187.2 187.5 161.7 197.7 195.2

M42 WB 133.6 149.5 151.9 173.9 197.9 189.1

A441 N 143.8 224.2 206.8 166.1 197.2 182.8

M42 EB 161.4 173.1 165.8 155.4 158.9 156.8

Total Journey

Time (mins) 13.4 15.8 15.3 13.6 15.9 15.5

Total Traffic

Held Back 1 2 1 8 61 111

Analysis of these results shows that:

• There is a small increase in total journey times in the morning peak hour with the

proposed development (15.8 minutes) compared to the 2021 base (13.4 minutes);

• There is no change in traffic held up in the morning peak hour with the proposed

development compared to the 2021 base;

• There is a small change in total journey times in the evening peak hour with the

proposed development compared to the 2021 base;

• There is an increase in the level of traffic held up in the evening peak hour with the

proposed development (61 vehicles) compared to the 2021 base (9 vehicles).

However, this represents less than 1% of traffic at the junction.

It is therefore concluded that the proposed development will not have an adverse impact on the overall operation of the junction. Notwithstanding this, it is proposed to provide a contribution to address residual impacts on specific arms and movements through the junction. MOVA (Microprocessor Optimised Vehicle Actuation) is a method of controlling traffic signals at junctions. It is a well established strategy for the control of traffic light signals at isolated junctions. It is the required signal control method for new junctions on the trunk road network that are not normally part of a linked network. MOVA is particularly well suited to the following conditions:


• Sites experiencing capacity difficulties under Vehicle Actuation (VA) control with congestion on one or more approaches.


• Where more than one junction is situated too close to be considered as isolated, there are ways in which two or more junctions can be linked by the use of MOVA control. Partially or even fully signalised roundabouts are a good example of a MOVA linking opportunity.

MOVA is generally accepted as the best option for signalled roundabouts and will generally provide in the region of 20% reduction in delays. A TRL research project found that an average 13% decrease in delay at 20 junctions running with MOVA compared with standard VA. This is based on the TRL study "RR279 MOVA: The 20-site trial” by J R Peirce and P J Webb. 1990".


5.8 M5 Junction 4

5.8.1 AM Peak Existing Year Summary

In the morning peak existing year model there are small amounts of queuing on all arms. However on the A419 Sandy Lane, at certain times in the peak hour queues of up to 21 – 25 vehicles build up, however this is considered acceptable. The circulating carriageway of the junction is busy but queues that build up on red signals clear effectively and the junction operates with in acceptable capacity levels. In the evening existing year model there are small amounts of congestion on all arms. However on the M5 northbound off-slip, at certain times of the peak hour queues build up along the slip road almost to the M5. The A419 Sandy lane is also heavily congested as in AM peak. The circulating carriageway of the junction is busy but after optimising the signals the queues that build up on red signals clear effectively and the junction operates with in acceptable capacity levels.

5.8.2 2021 AM Peak Do Minimum

The junction operates considerable worse than in the 2005 base year scenario. There are longer queues on the A419, A38 north and A38 south, this is in spite of some small adjustments made to optimise the signal timings. The southern section of the circulating carriageway of the junction between the A38 south arm entry and the A419 Sandy Lane exit is also heavily congested at times; this can be seen in Figure 5.9. The M5 northbound off-slip also suffers from large queues in the 2021 base year scenario and eventually near the end of the peak hour the queue is long enough to create tailbacks on the M5 mainline. Figure 5.9: 2021 AM Peak (M5 J4) Do Minimum 08:34

5.8.3 2021 AM Peak Background Growth & Development Trips

The queues on the M5 southbound off-slip and A38 north are worse than in the do minimum scenario. There is also further queuing and congestion on the circulating carriageway. The congestion on the above arms and the circulating carriageway also creates a large queue on the A38 south arm (Figure 5.10). The additional traffic on both of the off-slips causes queues past the end of the diverge and this in turn effects the north and southbound main line flows. As a result large queues develop on the M5.


This additional congestion and queues are due to the large amounts of traffic travelling towards Longbridge on the A38. It is also worth noting that all 5 arms become heavily congested after only 5 minutes of the peak hour (08:05 to 08:10) In comparison to the do minimum scenario it is clear that the M5 southbound and northbound off-slips are operating over acceptable capacity and this is where additional capacity would be needed at the junction to accommodate the Longbridge AAP development traffic. Figure 5.10: 2021 AM Peak (M5 J4) No Mode Shift 08:34


As the reduction in traffic across the junction due to the mode shift assumptions is only 75 vehicles the network operates in much the same way as the 2021 base + development without mode shift network. There are large queues on all arms and this congestion and queues on the junction creates queues on the M5 northbound and southbound off-slips. The only improvement in terms of the comparison between this network and the 2021 without mode shift is that fewer vehicles are waiting to enter the network at the end of the peak hour. As in the without mode shift network additional capacity would be required at the M42 southbound and northbound off-slips.


The junction is shown to operate considerably worse than in the base year scenario. Soon into

the modelled period all the M5 northbound off-slip, A38 north, A38 south and A419 all have

queues build up rapidly. There is also queuing which creates congestion on the southern

section of the circulator carriageway. The congestion also causes queues to extend along the

M5 northbound off-slip to the point where tail backs are noted on the M5 northbound main line

carriageway. This can be seen in Figure 5.11.


Figure 5.11: 2021 PM Peak (M5 J4) Do Minimum 17:45


When compared to the do minimum network, the queues in the without mode shift network are worse across the junction. There are larger queues on the A38 north and south, and the circulating carriageway is also further congested. As in the do minimum scenario the A419 and M5 northbound off-slip are heavily congested, and the queues are longer than in the do minimum scenario and build quicker (Figure 5.12). Again the M5 northbound main flow is affected. In comparison to the do minimum scenario it is clear that the M5 northbound off-slip is operating over capacity and this is where additional capacity would be needed at the junction to accommodate the Longbridge AAP development traffic. Additional capacity would also be needed at the A38 north and south arms to accommodate the Longbridge development traffic, as well as some additional capacity for the circulating carriageway. Figure 5.12: PM Peak (M5 J4) No Mode Shift 17:45


5.8.7 2021 PM Peak Background Growth, Development Trips & Mode Shift

The reduction in traffic due to the mode shift assumptions has almost no effect on the operation of the network when compared to the without mode shift scenario. The reduction in vehicles across the network is only 27. Queues as shown in Figure 5.12, are again present, however journey times across the junction are slightly reduced. The operation of the junction is not considered acceptable and compared to the do minimum network the with mode shift network operates less efficiently. As in the without mode shift network it is clear that additional capacity would also be needed at the A38 north and south arms to accommodate the Longbridge development traffic.

5.8.8 Summary

It is clear from the results presented in this note that the addition of development traffic, whether it be with or without mode shift, has a negative impact on the operation of the junction, and this is especially noticeable in the evening peak. However it must be noted that the M5 junction 4 will be heavily congested and operates at unacceptable capacity levels in the 2021 do minimum scenarios for the morning and evening peak. When compared to the 2021 do minimum scenario, queues and congestion for the development scenarios are worse for each arm in both time periods. It is also of a concern that the increase in congestion on the M5 off-slip roads causes the M5 to be delayed, which reduces the ability of the models to allow traffic to pass though it. Journey times were extracted from each of the models as another indicator of the performance of the network. The results are displayed in Table 5.10 and are summarised as follows:

• It can be seen that the total journey times for vehicles across the network are higher in

the development scenarios than in the 2021 do minimum scenario;

• In the morning peak hour, the arm with the most noticeable slower journey times

between the do minimum network and the development scenarios is the M5

southbound off-slip;

• In the morning peak hour, the arm with the most noticeable slower journey times

between the do minimum network and the development scenarios is the A38 south.

The conclusion that can be drawn from these results is that the addition of the Longbridge development traffic will have a significant impact on the junction in both peaks. Queuing will become a significant issue on all arms of the junction in the morning and evening peak, and the M5 mainline flow will be affected. It must also be stated that the mode shift assumptions do not bring any significant alleviation to the network. Mitigation will be required at several parts of the junction. Table 5.9 M5 Junction 4 Network Comparisons

Model Matrix Totals

Vehicles not

entering Network

Extensive Queues Mitigation Required

AM 2021 Do Minimum

14060 1104

• A419

• A38(N)

• A38 (S)

• M5 Northbound off-slip

• M5 Northbound

• A419

• A38(N)

• A38 (S)


• M5 Northbound

AM 2021 Development

Trips 15521 6632

• A419

• A38(N)

• A38 (S)


• M5 Northbound

• M5 Southbound off-slip

• M5 Southbound

• A419

• A38(N)

• A38 (S)


• M5 Northbound


• M5 Southbound

AM 2021 Mode Shift

15446 6256 • A419

• A38(N)

• A419

• A38(N)


• A38 (S)


• M5 Northbound


• M5 Southbound

• A38 (S)


• M5 Northbound


• M5 Southbound

PM 2021 Do Minimum

13313 2687

• A419

• A38(N)

• A38 (S)


• M5 Northbound

• Gyratory (Southern Section)

• A419

• A38(N)

• A38 (S)


• M5 Northbound


PM 2021 Development

Trips 14569 3437

• A419

• A38(N)

• A38 (S)


• M5 Northbound


• A419

• A38(N)

• A38 (S)


• M5 Northbound


PM 2021 Mode Shift

14511 3361

• A419

• A38(N)

• A38 (S)


• M5 Northbound


• A419

• A38(N)

• A38 (S)


• M5 Northbound


Table 5.10: M5 Junction 4 No Mitigation Journey Times

2021 – Do Minimum

2021 Base + Dev – Without Mode

Shift

2021 Base + Dev – With Mode

Shift


1 M5 Sbound Off-

slip A38 N 82.4 39.3 325.4 43.1 316.7 37

2 M5 Sbound Off-

slip A38 S 79.1 47.7 318.5 48 302.4 40

3 M5 Sbound Off-

slip M5 South 0 0 0 0 0 0

4 M5 Sbound Off-

slip A491 121.6 94.1 350.8 99.2 349.1 82.4

5 M5 Sbound Off-

slip M5 North 0 0 0 0 0 0

6 A38 N A38 S 86.3 81.2 77.4 62.9 73 62.4

7 A38 N M5 South 79.9 69.4 78.4 69.6 73.9 71

8 A38 N A491 119.8 99.2 128.2 106.6 117.9 113.5

9 A38 N M5 North 166.3 111.1 162.7 130 157.1 138.7

10 A38 N A38 N 0 0 0 0 0 0

11 A38 S M5 South 49.4 60.5 64.1 65 54.3 70.8

12 A38 S A491 71.6 89.2 76.5 99.4 75.2 106.8

13 A38 S M5 North 144.8 105.8 147.9 148.4 140.7 153.8

14 A38 S A38 N 157 135.5 162.1 176.6 151.7 185.2

15 A38 S A38 S 0 0 0 0 0 0

16 M5 Nbound Off-

slip A491 133.7 166.6 55.7 161.9 51.4 158.9

17 M5 Nbound Off-


18 M5 Nbound Off-

slip A38 N 199.8 170.3 256.4 165.4 248.1 164.7

19 M5 Nbound Off-

slip A38 S 226.3 198.3 279.7 184.2 284.5 180

20 M5 Nbound Off-



21 A491 M5 North 55.1 105.5 54 112.3 59.1 110

22 A491 A38 N 68.2 108.6 65.3 107.6 67.9 103.9

23 A491 A38 S 91.3 126 87.4 121.9 89.6 120.7

24 A491 M5 South 104.7 138.7 102.5 134.1 102.2 121.1

25 A491 A492 0 0 0 0 0 0

26 M5 Northbound Under

Junction 7.3 7.4 7.4 7.4 7.3 7.4

27 M5 Southbound Under

Junction 7.4 7.5 8 7.5 8 7.5

Total Journey Time (Minutes) 34.2 32.7 46.8 34.2 45.5 33.9


Total Traffic Held Back 1104 2687 6632 3437 6256 3361

5.8.9 Mitigation Measures

Junction improvements for the M5 junction 4 have been developed by the Highway Agency,

and include:

• Changes to lane markings throughout the junction;

• Circulating carriageway widened from 3 lanes to 4 within the vicinity of the A38 (S),

resulting in realigned roundabout;

• Circulating carriageway realigned in the vicinity of A38 (N);

• Additional lane added on the approach to the roundabout from the M5 northbound off-

slip, to provide a dedicated left turn to the A491;

• Realignment of entry/exit between M5 northbound off-slip and A491;

• Circulating carriageway in the vicinity of the A491 widened from 3 lanes to 4.

These improvements are shown on preliminary sketch design Drawing 50010TBMD_006. These improvements have been modelled in VISSIM with the future year traffic flows with the development proposals. The results of this analysis are summarised in Table 5.11. Table 5.11: M5 Junction 4 Mitigation Journey Times

2021 – Do Minimum

Included for comparison

2021 Base + Dev – Without Mode

Shift With

Improvements

2021 Base + Dev – With Mode

Shift, with Improvements


1 M5 Sbound Off-

slip A38 N 82.4 39.3 28.2 30.6 27.8 32.7

2 M5 Sbound Off-

slip A38 S 79.1 47.7 40.5 68.6 40.5 70.1

3 M5 Sbound Off-


4 M5 Sbound Off-

slip A491 121.6 94.1 85.5 138.6 84.8 136.6

5 M5 Sbound Off-


6 A38 N A38 S 86.3 81.2 26.5 35.3 26.8 33.6

7 A38 N M5 South 79.9 69.4 40.3 98 44 89.7

8 A38 N A491 119.8 99.2 77.2 151.3 79.3 145.8

9 A38 N M5 North 166.3 111.1 98.4 142.1 99 132.6

10 A38 N A38 N 0 0 0 0 0 0

11 A38 S M5 South 49.4 60.5 40 72 43.4 72.9

12 A38 S A491 71.6 89.2 61.6 128.3 59 125.2

13 A38 S M5 North 144.8 105.8 87.4 110.9 89.2 107.2

14 A38 S A38 N 157 135.5 121.9 118.5 115.6 123.6

15 A38 S A38 S 0 0 0 0 0 0


16 M5 Nbound Off-

slip A491 133.7 166.6 95.6 80.2 71.1 109.3

17 M5 Nbound Off-


18 M5 Nbound Off-

slip A38 N 199.8 170.3 158.7 94.7 123.4 104.3

19 M5 Nbound Off-

slip A38 S 226.3 198.3 171.8 109.3 147.7 125.2

20 M5 Nbound Off-


21 A491 M5 North 55.1 105.5 158.7 29.4 102.4 30.3

22 A491 A38 N 68.2 108.6 179.1 108.6 167.9 103.2

23 A491 A38 S 91.3 126 202.2 152.9 188.3 151.5

24 A491 M5 South 104.7 138.7 190.7 170.7 178.3 166.4

25 A491 A492 0 0 0 0 0 0

26 M5 Northbound Under

Junction 7.3 7.4 7.2 73 7.2 7.3

27 M5 Southbound Under

Junction 7.4 7.5 7.3 7.4 7.3 7.4

Total Journey Time in seconds (minutes)

34.2 32.7 31.3 30.9 28.4 31.3


Total Traffic Held Back 1104 2687 2226 3033 1989 2711

Table 5.12 shows a summary of the average journey times for each approach arm. Table 5.12: Summary of Average Journey Times by Approach (in seconds)

AM peak PM Peak

2021

Base

flows,

existing

layout

2021

With

development,

no mode

shift,

proposed

layout

2021 With

development,

with mode

shift,

proposed

layout

2021

Base flows,

existing

layout

2021

With

development,

no mode

shift,

proposed

layout

2021 With

development,

with mode

shift,

proposed

layout

Total Journey

Time (secs) 2052 1879 1703 1962 1855 1874

M5 SB 283.1 154.2 153.1 181.1 237.8 239.4

A38 (N) 452.3 242.4 249.1 360.9 426.7 401.7

A38 (S) 422.8 310.9 307.2 391 429.7 428.9

M5 NB 559.8 426.1 342.2 535.2 284.2 338.8

A491 319.3 730.7 636.9 478.8 461.6 451.4

Total Traffic

Held Back 1104 2226 1989 2687 3033 2711

This shows that, overall, in the morning peak hour there is a decrease in journey time through the junction compared to the results for 2021 with no development and no improvements. However, there is a corresponding increase in traffic held up that cannot enter the junction. Analysis of the results by approach shows that journey times from the M5 north, M5 south, A38 north and south will be less than 2021 with no development and no junction improvements. Journey times on A491 increase. The operation of the junction has been biased to minimise journey times and delays on the M5 slip roads, to the detriment of reducing green-time to the A491. If the junction is optimised, there would be less queues and delays on the A491, but considerably more queues and delays on the M5 off-slips. The impact of mode shift is relatively minor. In the evening peak hour, there is also a decrease in journey time through the junction with the development related traffic and the improvement scheme compared to 2021 with no development and no improvements. There is an increase in traffic held up, but this is not considered to be significant. Journey times from the M5 south and A491 decrease, whilst


journey times from M5 north, A38 north and A38 south increase. The impact of mode shift is relatively minor. It can therefore be concluded, that if the junction is considered as a whole, the improvement scheme mitigates the impact in both the morning and evening peak hours but results in a more traffic held up.

5.9 Summary and Conclusions

The impact of the AAP has been assessed with respect to the following junctions:

• M42 J1;

• M42 J2;

• M5 J4.

These junctions are likely to receive the largest change in traffic flows as a result of the

proposed AAP. The analysis of these junctions has been agreed with the Highways Agency.

It was agreed with the stakeholders (BCC, Worcestershire County Council and the Highways

Agency) that isolated VISSIM models would be the most appropriate way to model the impacts

on the Strategic Road Network.

A Local Model Validation Report has been developed which set out the development and

validation of micro-simulation traffic models (VISSIM) to support the development of the

Longbridge Area Action Plan (AAP).

Future year traffic flows were developed based on a combination of TEMPRO and NRTF traffic

growth combined with the predicted future demand for travel generated by the AAP.

The following can be concluded about the operation of the junctions in the future year with

proposed development:

M42 J1

• The junction is operating within capacity at present, with small amounts of congestion in

each peak hour. All vehicles are able to enter the network;

• In 2021, traffic growth adds traffic to the junction, but it is predicted to operate at a

satisfactory level;

• In 2021 with the addition of the development related traffic (and no mode shift), travel

times;

• Generally, the signals do not block back in both the morning and evening peak hours.

• The merge on the A38 southbound causes some queuing, particularly in the evening

peak hour with the addition of the development related traffic. These queues have an

impact on the operation by backing up onto the gyratory disrupting the flow. However,

there is no blocking back to the mainline flow on the motorway. Queues do not extend

to the mainline flows on the motorway in both the morning peak and evening peak

hours;


in both the morning and evening peak hours;

• There is a slight deterioration in journey times in the morning and evening peak hour

peak hour with the proposed development compared to the 2021 base on all

approaches. However, the overall change is not considered to be significant;

• There is an increase in traffic held up in the morning peak hour from 7 vehicles in the

base compared to 94 vehicles with the proposed development (no mode shift) and 51

vehicles with mode shift;

• There is an improvement in journey times from A38 south, A38 north and B4096 north

in the evening peak hour with mode shift;

• There is a slight increase in traffic held up in the evening peak hour with the proposed

development (51 vehicles with no mode shift and 25 vehicles with mode shift) and the

improvements compared to the 2021 base (14 vehicles).


M42 J2

• Generally, the signals do not block back in both the morning and evening peak hours;

• There are some queues on the off-slips but these do not extend to the mainline flows

on the motorway in both the morning peak and evening peak hours;


in both the morning and evening peak hours;

• There is a small increase in total journey times in the morning peak hour with the

proposed development (15.8 minutes) compared to the 2021 base (13.4 minutes);

• There is no change in traffic held up in the morning peak hour with the proposed

development compared to the 2021 base;

• There is a small change in total journey times in the evening peak hour with the

proposed development compared to the 2021 base;

• There is an increase in the level of traffic held up in the evening peak hour with the

proposed development (61 vehicles) compared to the 2021 base (9 vehicles).

However, this represents less than 1% of traffic at the junction.

It is therefore concluded that the proposed development will not have a perceptible impact on

the operation of the junction.

M5 J4

• In the morning and evening peak hour, there are currently small amounts on congestion;

• By 2021 junction will operate considerably worse than in the 2005 base year scenario, with longer queues on the A419, A38 north and A38 south;

• The addition of the development related traffic these queues are exacerbated in both the morning and evening peak hours, with further queuing and congestion on the circulating carriageway;

• It is therefore concluded that the AAP has an adverse impact on the operation of M5 j4. Accordingly, an improvement scheme has been developed to mitigate the impact of the AAP. These mitigation measures have been developed by the Highways Agency and are shown on preliminary sketch design Drawing 50010TBMD_006;

• The result of the analysis with the improvement scheme shows that, overall in the morning peak hour there is a decrease in journey time through the junction compared to the results for 2021 with no development and no improvements. The impact of mode shift is relatively minor;

• In the evening peak hour, there is also a decrease in journey time through the junction with the development related traffic and the improvement scheme compared to 2021 with no development and no improvements. There is an increase in traffic held up, but this is not considered to be significant. Journey times from the M5 south and A491 decrease, whilst journey times from M5 north, A38 north and A38 south increase. The impact of mode shift is relatively minor.

It can therefore be concluded, that if the junction is considered as a whole, the improvement scheme mitigates the impact in both the morning and evening peak hours but results in a more traffic held up.

Conclusions and Recommendations


6.1 Introduction

This section outlines the main conclusions of the model and any key recommendations. The

main conclusions relate to the results of the three scenarios, for traffic held up and journey time,

the two option tests and the strategic road network impact.

6.2 Area-Wide VISSIM Model Conclusions

Scenarios 2 and 3 show a particularly robust network, despite approximately 4000 extra

vehicles modelled compared to Scenario 1. However, the amount of vehicles held up in both

peaks in Scenario 2 and 3 is more than in the relevant Scenario 1 model. Although the

percentage of the matrix unassigned in the PM peak is less in Scenario 3 and only half a

percent more in Scenario 2 compared to Scenario 1.

The results of the sensitivity option testing highlights the robustness of the network, with similar

results to Scenario 2 and 3, albeit on a lesser scale, because the traffic demand is

approximately 1200 vehicles fewer.


In the AM peak the improvements made to the AAP network to mitigate the impact of the

development trips have been successful as no development trips are unassigned and there are

only transient queues in the AAP area. This could be as a result of gating as all the traffic

unassigned to the network is at external zones (Figure 3.1 and 3.5). In a strategic model, like

PRISM, these trips would have the potential to find an alternative route and reassign to an area

of the network where there is less congestion, potentially causing a congestion problem

elsewhere. However, given the time constraints and capabilities of the model and the network,

strategic re-assignment was not possible.

These peripheral junctions suffer as a consequence of an increase in external to external trips

through the area. The inclusion of the development traffic increases the problem at the

peripheral junctions.

The sensitivity option testing highlights the problem of external junctions unable to cope with an

increased travel demand. Similar external locations have traffic unassigned to the network as

in Scenario 1.


In the PM peak, improvements made to the Hopwood junction capacity have eliminated any

previously unassigned trips. However other parts of the network were congested, particularly

around Longbridge Lane because of its insufficient capacity at the interchanges.

Traffic is held up at the Park and Ride plus Development site in Scenario 2 and 3 (Figure 3.7),

because of the inclusion of the development traffic at this location. When the AAP trips are

included, it more than doubles the number of vehicles attempting to exit this site. The junction

and Longbridge Lane cannot cope with this increased trip demand; as a result traffic is

unassigned to the network.

6 Conclusions and Recommendations


The sensitivity option testing has a negligible number of vehicles unable to exit the Park and

Ride plus Development site during the peak. This is due to queues which form along

Longbridge Lane from the interchanges and not the Park and Ride junction. The queues which

form back to the Park and Ride interchange from the Longbridge Lane / Turves Green /

Coombes Lane interchange hinder vehicles wishing to exit the site.

However, there is scope to extend the site to connect it with Tessall Lane as possible

mitigation, which could reduce the number of trips unassigned to the network and impact on

Longbridge Lane.

6.2.3 General Network Performance

Scenario 2 and 3 mitigate the AAP development in the area but do not mitigate the forecast background traffic growth because there are some negative impacts on the wider network. In Sensitivity Option Test 1 and 2, when the background growth is removed, the AAP mitigates its own impact as in general terms they are broadly similar in network performance to Scenario 1, i.e. conditions that could arise on the network in any event. Table 6.1, 6.2 and 6.3 demonstrate this through an examination of the Scenarios and Option Tests related to network wide performance indicators. Table 6.1: Summary of Total Journey Time through Key Strategic Routes

Model AM Peak (minutes) PM Peak (minutes)

Scenario 1 169.2 185.1

Scenario 2 219.2 222.5

Scenario 3 201.2 202.4

Option Test 1 163.8 183.3


Table 6.2: Summary of Average Network Car Speed

Table 6.3: Summary of Average Delay per Vehicle

Model AM Peak (minutes) PM Peak (minutes)

Scenario 1 4.0 3.0

Scenario 2 4.8 5.6

Scenario 3 4.0 4.4



Queues form in the network in Scenario 1 in 2021 (Figure 3.2 and 3.4) when there was no

development traffic. The introduction of the development trips highlighted the problem that the

current network infrastructure, outside the immediate area of the proposed AAP cannot cope in

its current configuration. Therefore even if the development did not go ahead, it is likely that the

wider network will be congested around certain locations in the future year. Improving part of

the network infrastructure could have a knock-on impact on the rest of the network due to

suppressed demand. However, instead of changing route choice because of likely congestion

elsewhere, people would:

• Change the mode the travel; or

• Alter the time of travel; or

• Relocate, to live in the area so they do not need to travel.

Model AM Peak (kph) PM Peak (kph)

Scenario 1 27.5 31.6






The journey times for key strategic routes through the Longbridge area have shown a negative

impact as a result of the proposed development. In Scenario 2 both peaks show a more

congested wider network, with slower journey times by 34 (19%) and 37 minutes (20%) in the

AM and PM peak respectively. However, the mitigation measures in the AAP area do go some

way to alleviating the impact in the vicinity of the development.

Scenario 3, with the introduction of demand management, improves the overall network

situation to typically within 10% of the performance of Scenario 1 in 2021. This is within

normally accepted day to day variations of traffic, so can be accepted as mitigating the effect of

the development on the wider network performance.

The average network car speed and delay experienced highlights the heavily congested

network in Scenario 1 (Table 3.14 – 3.17). Scenarios 2 and 3 show slower speeds and more

delay than Scenario 1 emphasising the increase in network wide congestion.

In the AM peak, the impact in terms of average network car speed is negligible, 24.5 kph and

27.4 kph for Scenario 2 and 3 respectively. This change in speed is less than 10% in the worse

case (Scenario 2).

In the PM peak the decrease in speed is 5.9 kph and 9.8 kph for Scenario 2 and 3 respectively.

The delay has also increased by 1.4 minutes and 2.6 minutes per vehicle in Scenario 2 and 3

respectively. This highlights the congestion in the wider network when the development trips

are included during the peak. Certain roads and junctions outside the immediate AAP area

cannot cope with the increased trip demand, which results in an increased delay and lower

network speed.

The sensitivity option testing emphasised that the proposed infrastructure changes in the AAP

area go some way to mitigating the potential impact of the development in this area. However,

parts of the wider network in its current configuration, particularly in the PM peak, cannot cope

with any increased trip demand. Some form of future intervention would be required to relieve

the potential congestion problems.

6.3 Strategic Road Network

There is no adverse impact on the operation of the M42 junction 1 and junction 2 with

development traffic and no infrastructure changes in the future year. There is a slight

deterioration in journey time in both peaks at these junctions and a slight increase in the

amount of traffic unable to enter the network. However, this deterioration in journey time is

negligible as the junctions still operate effectively during both peaks.

There is an improvement in the evening peak with mode shift at the M42 junction 1 from the

A38 north and south and B4096 south. However traffic is held up along the A38 north arm in

both peaks without mode shift (87 vehicles and 37vehicles in the AM and PM peak respectively)

compared to the 2021 base (0 vehicles).

The operation of the M42 junction 2 in both peaks is generally very similar between 2021 base

and 2021 base plus development. There is an increase in the level of traffic held up in the

evening peak hour with the proposed development (61 vehicles) compared to 2021 base (9

vehicles). However, all these trips are restricted on the motorway westbound due to its

saturation flow and not the junction operation.

At the M5 junction 4 the addition of the Longbridge development traffic has a significant impact

on the junction in both peaks. Queuing becomes a major issue on all the arms and the M5 flow

is affected. Therefore mitigation at this junction was required. Proposed junction improvements

included (Drawing 50010TBMD_006):

• Lane marking changes;

• Circulating carriageway widened from 3 lanes to 4 within the vicinity of the A38 (S);

• Circulating carriageway realigned in the vicinity of A38 (N);


• An additional lane on the approach to the roundabout from the M5 northbound off-slip

to provide a dedicated left turn to the A491;

• Realignment of the entry / exit between M5 northbound and A491;

• Circulating carriageway in the vicinity of the A491 widened from 3 to 4 lanes.

The results of the analysis with the improvement scheme showed a decrease in journey time in

both peaks for the development compared to the base 2021 with no improvements. However

more traffic is held up, but this is not considered to be significant. The total journey time

through the junction in the development without mode shift is 3 minutes and 2 minutes faster in

the AM and PM peak respectively compared to the 2021 base with no improvements. The

impact of the mode shift is relatively minor.

Therefore the M5 junction 4 improvement scheme mitigates the impact of the development in

both peaks but more traffic is held up.

6.4 Recommendations

The proposed AAP infrastructure has largely mitigated the impact of the development trips

within the AAP. In the AM peak, the A38 Bristol Road has seen a negligible negative impact

and all the development trips are assigned to the network. The proposed network changes

have also reduced the impact of increased vehicles particularly in the PM peak along the A441.

However, in the PM peak, trips at the Park and Ride plus Development site are restricted. A

potential mitigation of linking this site with Tessall Lane could reduce this impact. An option to

provide a contribution to implement SCOOT / MOVA at this junction and in the wider network

would improve the junction capacities (see section 2.4.5.1) and go some way to alleviating the

potential problems in the area.

Based on current highway layouts, parts of the network cannot cope at peak periods with the

increased number of trips forecast. However, for the most part these locations show significant

queuing even in Scenario 1. Therefore it cannot be said that the AAP development has caused

these issues. The issue is not just the AAP but current network restraints which would be

exacerbated by wider growth on the network.

Further improvements and interventions may be appropriate to address issues raised as a

result of background growth (Scenario 1). These should be addressed through the wider

planning system as necessary.

Appendix A: Critical Queues on the

Network


Rose Hill Roundabout (Scenario 1 AM Peak)

7 Appendix A: Critical Queues on the

Network

Rose Hill Roundabout

Zone 20 Zone 9

Queues form along the length of the road back from the roundabout by the end of the peak hour


Redhill Road / A441 Redditch Road (Scenario 1 AM Peak)

Longbridge Lane / A441 Roundabout (Scenario 1 AM Peak)

Redhill Road / A441 Roundabout

Zone 4

Zone 3

Zone 5

Queues form back to zone 3 from the Redhill Road / A441 Roundabout

Queues form back towards zone 4 and 5 and along Redhill Road

Longbridge Lane / A441 Birmingham Road Roundabout

During the peak hour, queues build up because of the inadequate capacity of Longbridge Lane / A441 Birmingham Road roundabout.


Redhill Road / A441 Redditch Road Roundabout (Scenario 1 PM Peak)

Redhill Road / A441 Redditch

Road Roundabout

Queues form back from the roundabout because of its poor capacity, resulting in traffic unable to exit zone 5 by the end of the peak.

Zone 5

Longbridge Lane / A441 Birmingham Road Roundabout


Hopwood Roundabout (Scenario 1 PM Peak)

Vehicles queue back to Longbridge Lane / A441 Birmingham Road roundabout

Hopwood Roundabout

Long queues build up during the peak as traffic cannot travel through Hopwood roundabout due to its insufficient capacity.


Park and Ride Site / Longbridge Lane (Scenario 1 PM Peak)

Cock Hill Lane Exit (Scenario 2 AM Peak)

Park and Ride Junction

Queues begin to form at the end of the peak (last 15 minutes)

Zone 24

Traffic is unable to exit Cock Hill Lane because of the heavy flow of traffic eastbound along the A38.


Longbridge Lane (Scenario 2 AM Peak)

Minor Roads North of Longbridge Lane (Scenario 2 PM Peak)

Signal Control 11

Signal Control 12

Queues build up from the two junctions on Longbridge Lane

Redhill Road / A441 Roundabout

Signal Control 12 (Longbridge Lane)

Queues along the minor roads restrict traffic exiting zones 4 and 5.

Zone 4

Zone 5


Longbridge Lane (Scenario 3 PM Peak)

Traffic Flow through AAP Area (Scenario 2 PM Peak)

To City Centre

To M5 J4

Zone 29

Zone 28

West Works Link

Steady flow of traffic, only transient queues

Zone 32

Zone 33

Signal Control 12

Signal Control 11

Queues form along Longbridge Lane and into the surrounding area

Appendix B: SRN Matrices


8.1 2005 and 2006 Background Matrices

8.1.1 M42 Junction 1 Zone Key A – M42 West B – M42 East C – A38 (N) Birmingham Road D – B4096 (N) Alcester Road E – B4096 (S) Alcester Road F – A38 (N) Birmingham Road AM Peak 2006 Background Growth Car Matrix

A B C D E F

A 0 3456 0 0 0 0

B 3650 0 109 10 33 319

C 0 283 0 15 141 696

D 0 33 1 0 51 198

E 0 39 131 25 0 21

F 0 296 387 207 6 0

Matrix Total: 10108 AM Peak 2006 Background Growth HGV Matrix

A B C D E F

A 0 665 0 0 0 0

B 702 0 12 2 2 27

C 0 8 0 5 4 76

D 0 5 4 0 0 2

E 0 3 5 0 0 0

F 0 24 49 8 0 0

Matrix Total: 1603 PM Peak 2006 Background Growth Car Matrix

A B C D E F

A 0 3172 0 0 0 0

B 3713 0 289 37 53 534

C 0 129 0 16 203 809

D 0 14 6 0 44 193

E 0 58 157 28 0 10

F 0 227 575 278 7 0

Matrix Total: 10552 PM Peak 2006 Background Growth HGV Matrix

A B C D E F

A 0 586 0 0 0 0

B 509 0 1 0 0 20

C 0 3 0 0 3 16

D 0 1 0 0 1 0

8 Appendix B: SRN Matrices


E 0 0 4 0 0 1

F 0 4 14 1 0 0

Matrix Total: 1164

8.1.2 M42 Junction 2 Zone Key A - A441 North B - Service Station C - M42 East D - A441 South E - M42 West AM Peak 2005 Background Growth Car Matrix

A B C D E

A 0 31 214 342 103

B 7 0 65 18 139

C 462 99 0 98 3551

D 579 24 31 0 338

E 101 104 3566 162 0


A B C D E

A 0 5 15 12 4

B 3 0 22 1 20

C 34 32 0 12 933

D 31 0 4 0 26

E 12 17 884 17 0


A B C D E

A 0 105 349 531 14

B 16 0 95 8 116

C 483 95 0 67 3453

D 407 21 14 0 202

E 177 136 3114 194 0


A B C D E

A 0 5 12 8 1

B 1 0 0 0 16

C 12 23 0 3 940

D 3 0 1 0 7

E 7 29 934 6 0

Matrix Total: 2008

8.1.3 M5 Junction 4 Zone Key A - M5 North


B - A38 North C - A38 South D - M5 South E - A491 AM Peak 2005 Background Growth Car Matrix

A B C D E

A 0 198 337 2027 90

B 155 0 211 292 138

C 550 246 0 87 140

D 2841 317 27 0 470

E 208 129 240 579 0


A B C D E

A 0 23 49 650 16

B 10 0 17 15 15

C 31 14 0 1 25

D 693 21 2 0 52

E 8 7 38 61 0


A B C D E

A 0 278 869 1538 425

B 52 0 275 349 176

C 398 88 0 50 326

D 2083 338 54 0 877

E 50 198 246 301 0


A B C D E

A 0 5 9 531 0

B 5 0 4 5 0

C 18 0 0 1 5

D 846 1 0 0 24

E 1 5 6 18 0

Matrix Total: 1484

8.2 2021 Background Matrices

8.2.1 M42 Junction 1 Zone Key A – M42 West B – M42 East C – A38 (N) Birmingham Road D – B4096 (N) Alcester Road E – B4096 (S) Alcester Road F – A38 (N) Birmingham Road AM Peak 2021 Background Growth Car Matrix


A B C D E F

A 0 4254 0 0 0 0

B 4493 0 127 12 38 371

C 0 329 0 17 164 810

D 0 38 1 0 59 230

E 0 45 152 29 0 24

F 0 345 451 241 7 0


A B C D E F

A 0 819 0 0 0 0

B 864 0 14 2 2 31

C 0 9 0 6 5 88

D 0 6 5 0 0 2

E 0 3 6 0 0 0

F 0 28 58 9 0 0


A B C D E F

A 0 3905 0 0 0 0

B 4571 0 338 43 62 622

C 0 151 0 19 236 943

D 0 16 7 0 51 225

E 0 68 183 33 0 12

F 0 265 670 324 8 0


A B C D E F

A 0 721 0 0 0 0

B 627 0 1 0 0 23

C 0 4 0 0 3 19

D 0 1 0 0 1 0

E 0 0 5 0 0 1

F 0 4 16 2 0 0

Matrix Total: 1429

8.2.2 M42 Junction 2 Zone Key A - A441 North B - Service Station C - M42 East D - A441 South E - M42 West AM Peak 2021 Background Growth Car Matrix

A B C D E

A 0 30 604 383 175

B 14 0 4 25 142

C 424 105 0 124 3551


D 431 82 67 0 304

E 183 167 3566 248 0


A B C D E

A 0 1 11 7 16

B 1 0 0 0 19

C 22 30 0 6 940

D 4 0 5 0 8

E 6 28 934 7 0


A B C D E

A 0 26 319 474 172

B 16 1 4 31 134

C 858 121 0 123 3491

D 417 52 101 0 243

E 154 128 3114 242 0


A B C D E

A 0 1 11 7 15

B 1 0 0 0 19

C 21 29 0 6 940

D 4 0 5 0 8

E 6 27 934 7 0

Matrix Total: 2041

8.2.3 M5 Junction 4 Zone Key A - M5 North B - A38 North C - A38 South D - M5 South E - A491 AM Peak 2021 Background Growth Car Matrix

A B C D E

A 0 258 439 2538 117

B 202 0 275 381 180

C 717 321 0 113 183

D 3557 413 35 0 613

E 271 168 313 755 0


A B C D E

A 0 30 64 814 21

B 13 0 22 20 20


C 40 18 0 1 33

D 868 27 3 0 68

E 10 9 50 80 0


A B C D E

A 0 359 1124 1926 550

B 67 0 356 451 228

C 515 114 0 65 422

D 2608 437 70 0 1134

E 65 256 318 389 0


A B C D E

A 0 6 12 665 0

B 6 0 5 6 0

C 23 0 0 1 6

D 1059 1 0 0 31

E 1 6 8 23 0

Matrix Total: 1862

8.3 Longbridge AAP Development Matrices – Without Mode Shift

8.3.1 M42 Junction 1 AM Peak Longbridge AAP Development – No Mode Shift

A B C D E F

A 0 0 0 0 0 0

B 0 0 0 0 0 0

C 0 0 0 0 0 197

D 0 0 0 0 0 0

E 0 0 0 0 0 0

F 0 0 63 0 0 0

Matrix Total: 260 PM Peak Longbridge AAP Development – No Mode Shift

A B C D E F

A 0 0 0 0 0 0

B 0 0 0 0 0 0

C 0 0 0 0 0 65

D 0 0 0 0 0 0

E 0 0 0 0 0 0

F 0 0 171 0 0 0

Matrix Total: 236


A B C D E

A 0 0 158 62 0


B 0 0 0 0 0

C 459 0 0 0 0

D 241 0 0 0 0

E 0 0 0 0 0


A B C D E

A 0 0 378 197 0

B 0 0 0 0 0

C 139 0 0 0 0

D 73 0 0 0 0

E 0 0 0 0 0

Matrix Total: 786


A B C D E

A 0 660 0 0 0

B 176 0 29 36 38

C 0 86 0 0 0

D 0 308 0 0 0

E 0 127 0 0 0


A B C D E

A 0 171 0 0 0

B 509 0 75 268 100

C 0 45 0 0 0

D 0 29 0 0 0

E 0 59 0 0 0

Matrix Total: 1256

8.4 Longbridge AAP Development Matrices – With Mode Shift

8.4.1 M42 Junction 1 AM Peak Longbridge AAP Development – Mode Shift

A B C D E F

A 0 0 0 0 0 0

B 0 0 0 0 0 0

C 0 0 0 0 0 153

D 0 0 0 0 0 0

E 0 0 0 0 0 0

F 0 0 51 0 0 0

Matrix Total: 204 PM Peak Longbridge AAP Development – Mode Shift

A B C D E F

A 0 0 0 0 0 0


B 0 0 0 0 0 0

C 0 0 0 0 0 56

D 0 0 0 0 0 0

E 0 0 0 0 0 0

F 0 0 136 0 0 0

Matrix Total: 193


A B C D E

A 0 0 156 57 0

B 0 0 0 0 0

C 448 0 0 0 0

D 218 0 0 0 0

E 0 0 0 0 0


A B C D E

A 0 0 370 179 0

B 0 0 0 0 0

C 137 0 0 0 0

D 69 0 0 0 0

E 0 0 0 0 0

Matrix Total: 755


A B C D E

A 0 650 0 0 0

B 174 0 22 35 36

C 0 56 0 0 0

D 0 298 0 0 0

E 0 115 0 0 0


A B C D E

A 0 169 0 0 0

B 501 0 51 260 91

C 0 40 0 0 0

D 0 28 0 0 0

E 0 57 0 0 0

Matrix Total: 1197

final traffic modelling report issued 200308

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