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Agile Construction Initiative

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Benchmark methodACI/DLV/ 96/017

AGILE CONSTRUCTION INITIATIVEAGILE CONSTRUCTION INITIATIVEAGILE CONSTRUCTION INITIATIVEAGILE CONSTRUCTION INITIATIVE THE STANDARD NEW ROAD PROJECT

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The Standard New Road Project

AuthorsDavid Madigan, Agile Construction Initiative

Copyright � University of Bath, 1997

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted inany form or by any means electronic, mechanical, photocopying, recording or otherwise without the priorwritten permission of the copyright holder.

Document control information:

Date of issue 31 March, 1997Document number ACI/DLV/ 96/017Circulation PublicVersion 3.00

To obtain a copy of this document contact ACI at:

School of ManagementUniversity of BathBath, BA2 7AYUnited KingdomTel: + 44 (0) 1225 826641Fax: + 44 (0) 1225 826135E-Mail: [email protected]: http://www.bath.ac.uk/Departments/Management/research/agile/


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Table of Contents

0. TABLE OF CONTENTS..................................................................................................................................3

1. INTRODUCTION..............................................................................................................................................4

1.1 THE AGILE CONSTRUCTION INITIATIVE .........................................................................................................41.2 THE PRINCIPLES OF BENCHMARKING..............................................................................................................41.3 THE PURPOSE OF THIS DOCUMENT .................................................................................................................5

2. PRODUCT BREAKDOWN STRUCTURE..................................................................................................6

2.1 DEVELOPING THE PRODUCT BREAKDOWN STRUCTURE.................................................................................62.2 HIGHWAYS AGENCY.......................................................................................................................................62.3 CESMM3........................................................................................................................................................72.4 ADVANTAGES AND DISADVANTAGES.............................................................................................................82.5 DETAILED COMPARISON .................................................................................................................................82.6 FINAL PRODUCT BREAKDOWN STRUCTURE....................................................................................................82.7 SIZING ELEMENTS............................................................................................................................................9

3. PRINCIPLES OF MEASUREMENT ..........................................................................................................11

3.1 GENERAL COMMENTS ON MEASUREMENT...................................................................................................113.2 EARTHWORKS ...............................................................................................................................................113.3 IN SITU CONCRETE.........................................................................................................................................153.4 CONCRETE ANCILLARIES ..............................................................................................................................153.5 DRAINAGE PIPES............................................................................................................................................183.6 PIPEWORK - MANHOLES...............................................................................................................................203.7 PILES..............................................................................................................................................................213.8 ROADS AND PAVING......................................................................................................................................21

4. RESULTS FROM PILOTS............................................................................................................................24

4.1 THE NEED FOR SIZING ITEMS.........................................................................................................................244.2 GENERAL DIFFICULTIES IN OBTAINING DATA................................................................................................24

5. CONCLUSIONS ..............................................................................................................................................25

6. ANNEX A - DERIVATION OF SIZING ITEMS FOR MANHOLES...................................................26

FIGURE 1 EARTHMOVING OPERATIONS...................................................................................................................11FIGURE 2 TYPICAL CROSS SECTION OF A ROAD ......................................................................................................22FIGURE 3 COMPOSITE CONSTRUCTION ...................................................................................................................23FIGURE 4 RIGID CONSTRUCTION .............................................................................................................................23FIGURE 5 LABOUR GANG HOURS VERSUS MANHOLE VOLUME ..............................................................................26

TABLE 1 HIGHWAYS AGENCY MEASUREMENT METHOD - SERIES...........................................................................7TABLE 2 MAIN CATEGORIES OF CESMM ................................................................................................................8TABLE 3 ADVANTAGES AND DISADVANTAGES OF BOQ AND CESMM..................................................................8TABLE 4 DETAILED COMPARISON OF BOQ AND CESMM ......................................................................................8TABLE 5 PRODUCT BREAKDOWN STRUCTURE .........................................................................................................9TABLE 6 EXCAVATION TIMES FOR DIFFERENT TYPES OF MATERIAL......................................................................13TABLE 7 EQUIVALENT QUANTITY OF EXCAVATION ...............................................................................................13TABLE 8 VARIATION OF EXCAVATION TIMES WITH MATERIAL TYPE .....................................................................14TABLE 9 EQUIVALENT QUANTITY OF EXCAVATION ...............................................................................................14TABLE 10 VARIATION OF MAKE AND FIX TIME WITH TYPE OF FORMWORK...........................................................16TABLE 11 SIMPLIFIED FORMWORK PRODUCTIVITY FACTORS.................................................................................16TABLE 12 CALCULATION OF EQUIVALENT QUANTITIES OF FORMWORK................................................................17


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Introduction

The Agile Construction Initiative

The Agile Construction Initiative (ACI) is a new project under thegovernment’s Innovative Manufacturing Initiative (IMI), funded by theEngineering and Physical Sciences Research Council (EPSRC). ACI has beenset up to research into the transfer of lean production practices pioneered byleading Japanese manufacturing companies to the UK civil engineeringindustry.

The leading industrial partner will be Balfour Beatty Civil EngineeringLimited (BBCEL) based in the UK. The research is being undertaken by theUniversity of Bath, School of Management.

The programme of work consists of a number of elements. Primarily, theproject will undertake benchmarking to compare the current performance ofthe UK construction industry with the best in the world. It will develop ideason what constitutes best practice in the construction industry. Best practicesidentified by the programme will be piloted by the Agile ConstructionInitiative within the industrial partners before being disseminated to theindustry at large. In parallel to this work research will be conducted onfinancial control systems, managing the value chain and life cycle assessment.

The principles of benchmarking

Benchmarking is a management tool that is currently enjoying a high profile.Many projects are being carried out under the banner of benchmarking and it isimportant to outline what ACI understands by the term.

ACI has adopted the following definition of benchmarking:

“Benchmarking is a systematic and continuous measurement process;a process of continuously measuring and comparing an organisation’sbusiness processes against business process leaders anywhere in theworld to gain information which will help the organisation takeaction to improve its performance.”1

In order to develop a methodology some additional principles have beenadopted, based on the work of the International Motor Vehicle Program(IMVP).

1. Standard products

2. Measures of performance 1 The definition was developed by the International Benchmarking Clearinghouse (IBC)


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3. Indicators of practice.

The use of standard products allows fair comparison to be made betweendifferent organisations. It is important to compare “apples to apples”. Thestandard product is defined by the set of activities that result in the constructionof the standard product.

Measures of performance are used to find the organisations that are capable ofdelivering superior performance to their customers. The starting point for leanthinking is the concept of value. Organisations exist to create value for theircustomers and this must be reflected in the measures of performance.

Indicators of practice are used a the stepping stone into deep case studies ofsuccessful organisations. They point to the best practices that allow theorganisations to deliver superior performance.

The purpose of this document

The overall benchmark method is described in full in the ACI Working Paper“Benchmark Method: Building on CESMM”. The purpose of this document isto describe one of the standard products that has been developed to benchmarkthe civil engineering industry. This standard product is a new roadconstruction. The document describes the activities that are included in thedefinition of the standard product and the principles of measurement that applyto these activities.


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Product breakdown structure

Developing the product breakdown structure

The product breakdown structure defines the construction products that whenassembled together on site make up the standard new road. The list was arrivedat by doing the following:

1. Excluding all products that were considered non-standard and for which itwould be difficult to get data from all participating projects.

2. Taking the 20% of components that represented about 80% of the cost ofthe standard product.

3. Generalising the component definitions to make it easier to get returnsfrom all participating projects.

This resulted in about fifty elements in the standard new road.

Two standard documents were using in generating the component definitions;the Highways Agency Bill of Quantities and the ICE’s CESMM3. These arerather different in character as a result of the generalisation in CESMM3 tomake it applicable to all civil engineering contracts.

The following sections contrast the two documents and then introduce the finalproduct breakdown structure for the new road project.

Highways Agency

The Highways Agency measurement method is organised into a number ofdifferent series of construction components.

Series 400 Safety Fences Safety Barriers And Pedestrian GuardrailsBeam Safety FencesVertical Concrete BarrierSeries 500 Drainage And Service DuctsDrains Sewers Piped Culverts And Service Ducts (Excludng Filter Drains, Narrow FilterDrains And Fin Drains)Fin Drains And Narrow Filter DrainsFilter DrainsLinear SoakwayChambersConcrete ChannelsSeries 600 EarthworksExcavationExcavation In Hard MaterialDeposition Of FillCompaction Of FillTopsoiling And Storage Of TopsoilGrassingCompletion Of Formati0nSeries 700 Pavements


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Sub BaseFlexible PavementRigid PavementBridge Decks.SurfacingSeries 1100 Kerbing footways and paved areasKerbs, Channels, Edgings And Combined Drainage And Kerb BlocksSeries 1200 Traffic Signs & RoadmarkingsRoadmarkings

• Table 1 Highways Agency measurement method - series

CESMM3

The applicable sections of CESMM3 are as follows:

Code DescriptionE EARTHWORKSF IN SITU CONCRETEG CONCRETE ANCILLARIESG1 Formwork: rough finishG2 Formwork: fair finishG3 Formwork: other stated finishG4 Formwork: stated surface finishG5 ReinforcementG8 Concrete accessoriesG81 Finishing of top surfacesI PIPEWORK - PIPESK PIPEWORK - MANHOLES ETCM STRUCTURAL METALWORKM5 Erection of members for bridgesN MISCELLEANOUS METALWORKN15 Bridge parapetsP PILESP1 Bored cast in place concrete pilesR ROADS & PAVINGR3 Sub-bases, flexible road bases and surfacingR4 Concrete pavementsR6 Kerbs, channels and edgingsR8 AncilliariesR82 Surface markingsW WATERPROOFINGX MISC.X1 FencesX18 Metal crash barriers


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• Table 2 Main categories of CESMM

Advantages and disadvantages

Highways Agency BoQ CESMM3UK Highways projects sitemeasurement systems will match thisformat well.

The performance on individualconstruction activities can becompared for non-highways andhighways sites

The match between BoQ items andsite activities is good.

The match will not be so good in allcases.

Little work has to be done on the BoQto turn it into the benchmark method.

More work has to be done .

Site performance isn’t recorded insame categories as BoQ

Site performance isn’t recorded insame categories as CESSM3

• Table 3 Advantages and disadvantages of BoQ and CESMM

Detailed comparison

Item Highways Agency CESMM3Placement of concrete Divides items according

to location in structures;superstructure, endssupports

Divides items accordingto type of pour; slab,wall, base, column

Distinguishes betweenconcrete mixes.

Excavation Separate items forcompactionUses Highways Agencymaterials definitions (inparticular chalk istreated separately)

Simpler materialsdefinitions

Formwork Uses Highways Agencyformwork definitions

Reinforcement Distinguishes betweenstraight and deformedreinforcement

• Table 4 Detailed comparison of BoQ and CESMM

Final product breakdown structure

The final product breakdown structure is shown in Table 5. The breakdown isbased on the Highways Measurement Method and CESSM. The breakdown issimplified to tie up with the way that data is collected on site.


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• Table 5 Product breakdown structure

Sizing elements

The final product breakdown structure is inadequate for making like for likecomparisons between different sites. The categories are too broad. To

Classification DescriptionC31 Insitu concrete in SuperstructureC32 Insitu concrete in End SupportsC33 Insitu concrete in Intermediate SupportsC34 Insitu concrete in Underpass/Culvert main constructionC7 Insitu concrete in blinding not exceeding 75mm in thicknessE11 Excavation of acceptable material; TopsoilE12 Excavation in cutting and other excavation other than topsoil and rockE311 Deposition of acceptable material in embankments and other areas of

fill; material other than topsoil and rockE322 Deposition of acceptable material in landscape areasE51 Topsoiling of varying thickness to surfaces sloping at 10 degrees or

less to the horizontalE52 Topsoiling of varying thickness to surfaces sloping exceeding 10

degrees to the horizontalE7 Completion of formationF11 Formwork in SuperstructureF12 Formwork in End SupportsF13 Formwork in Intermediate SupportsF14 Formwork in Underpass/Culvert main constructionI11 Carrier drain, internal diameter from greater than 150mm and less than

or equal to 450mm, in a trench depth to invert less than or equal to 3mI12 Carrier drain, internal diameter from greater than 450mm and less than

or equal to 750mm in trench depth to invert less than or equal to 3mI21 Edge of carriageway drain; narrow; in trench depth not exceeding 1.5mI3 ManholeI4 GulliesP1 Vertical 600 or 750mm diameter cast-in-place main piling (boring,

concrete and reinforcement)P2 Vertical 900mm or 1050mm diameter cast-in-place main piling (boring,

concrete and reinforcement)R11 Granular sub-base in main carriagewayR12 Lean concrete sub-base in main carriagewayR22 Heavy Duty Macadam basecourse in main carriagewayR23 Heavy Duty Macadam roadbase in main carriagewayR31 Wearing Course in main carriagewayR32 Continuous Reinforced Concrete Pavement in main carriagewayS1 High yield steel deformed bar reinforcement in superstructureS2 High yield steel deformed bar reinforcement in end supportsS3 High yield steel deformed bar reinforcement in intermediate supportsS4 High yield steel deformed bar reinforcement in underpass/culvert main

constructionSF1 Safety fence; untensioned single sided open box beam straight or

curved exceeding 50 metres radiusSF2 Safety fence; tensioned double sided corrugated beam straight or

curved exceeding 50 metres radius


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overcome this the concept of sizing elements are introduced. These work asfollows:

1. The site submits are return for a given element in the product breakdownstructure. The return contains the quantity of the item produced.

2. The product breakdown structure categories are too general for faircomparison so the quantities are adjusted using sizing elements.

3. The quantity adjustment means that the comparison is being made againstthe same construction product.

This is best illustrated by an example.

1. Formwork performance data is collected according to the part of thestructure that is being constructed; superstructure, end supports etc.

2. However, two end supports are not the same design and will containdifferent mixes of individual types of formwork.

3. In order to make fair comparison, the quantities of different classes offormwork are listed and then these are converted to equivalent quantities ofa single class of formwork.

4. The conversion is based on the different times it takes to fix each differentclass of formwork according to the CESSM3 Price Database 1996/7.

The classes that are used are i) horizontal, sloping or battered ii) vertical andiii) curved. The quantities of each of these that go together to make up the totalquantity on the return are listed. They are then converted to equivalentquantities of horizontal formwork. The total quantity of horizontal equivalentis then used to compare performance.


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Principles of measurement

General comments on measurement

The benchmark method requires the following data to supplied for each of theactivities that make up the standard new road project.

1. The total quantity of the component produced by the activity.

2. The amount of working time that the construction gang spent producingthe component.

3. The theoretical capability of the construction gang based on the plantconfiguration in use.

In order to make sure that a fair comparison is made between projects anumber of additional factors will be measured that may affect performance. Ifnecessary the affect of these will be removed before project performance iscompared.

The following sections define the principles of measurement for differentclasses of construction components that make up the new road project.

Earthworks

Excavation

General

2 Taken from Barnes, M (1992) CESMM3 Handbook, London: Thomas Telford

Import

Disposal

Double handling

Re-use

• Figure 1 Earthmoving operations2


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Excavation and filling/compaction are separated. The reason for this is becauseof the varying destinations and sources for excavated and filling material. Thisis shown in Figure 1.

Effort calculation

The amount of effort required is calculated for each piece of excavation plant.The time is then the amount of time that the piece of plant is working. Thetime includes time that the plant is idle awaiting trucks to load and plantbreakdowns, but excludes meal breaks and breaks for poor weather. Thecalculation is the same for motor scrapers. They will not suffer idle timeawaiting trucks but may have idle time waiting for access to the cutting area.

As the productivity may vary according to the type of material beingexcavated, this information will be included on the returns to allow itssignificance to be investigated.

Capability calculation

The rate of production that the excavation plant should be capable ofproducing working 100% of the time according to the manufacturersspecification. The rate of production will need to take into account theproperties of the material being excavated, in particular the bulking factor ofthe material.

Sizing factors

The rate of production of excavators is related to the type of material beingdug. In order to make fair comparison on excavation, the returns need to beadjusted to a common material type. The default material is “Medium hardclay with cobbles”. Returns for other types of materials will be adjusted. Thequantities will be adjusted to equivalent quantities of the default material.

The following adjustments will be made to the working time according to thetype of material being excavated:


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Material being excavated Multiplier (Equivalent quantity =measured measured * Multiplier)

Firm sand 0.70

Soft loam, sandy clay 0.85

Medium hard clay with cobbles 1.00

Gravel 1.10

Broken stone 1.25

Stiff clay with boulders 1.33

Soft chalk 2.50

• Table 6 Excavation times for different types of material

Sample calculation:

Material Quantity (m3) Equivalentquantity (m3)

Medium hard clay with cobbles 40,000 40,000

Broken stone 60,000 75,000

TOTAL 100,000 115,000

• Table 7 Equivalent quantity of excavation

Working time = 262 hours

Gross productivity = 262/100,000 = 2.62 per 1000m2

Adjusted productivity = 262/115,000 = 2.28 per 1000m2

Factors to measure

1. The average distance the material is being hauled over (in km)

2. Whether the haul is all contained within the site or goes on to public roads.(1 = within site, 2 = on public roads).

3. The destination of the material.

Filling and compaction

General comments

Filling and compaction will be measured as a single activity.

Effort calculation

The amount of effort is calculated for each piece of compaction plant. Theamount of effort will be the working time of the compaction plant. The time


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includes time that the plant is idle awaiting material to compact and plantbreakdown, but excludes meal breaks, breaks for poor weather.


The rate of production that the excavation plant should be capable ofproducing working 100% of the time according to the manufacturersspecification and the appropriate design tables of numbers of passes requiredfor the material being compacted.

Sizing factors

1. The material being compacted.

The rate of production of excavators is related to the type of material beingdug. In order to make fair comparison on excavation, the returns need to beadjusted to a common material type. The default material is “Medium hardclay with cobbles”. Returns for other types of materials will be adjusted. Thequantities will be adjusted to equivalent quantities of the default material.

The following adjustments will be made to the working time according to thetype of material being excavated:

Material being excavated Multiplier (Equivalent quantity =measured quantity * Multiplier)

Firm sand 0.70

Soft loam, sandy clay 0.85

Medium hard clay with cobbles 1.00

Gravel 1.10

Broken stone 1.25

Stiff clay with boulders 1.33

Soft chalk 2.50

• Table 8 Variation of excavation times with material type

Sample calculation:

Material Quantity (m3) Equivalentquantity (m3)

Medium hard clay with cobbles 40,000 40,000

Broken stone 60,000 75,000

TOTAL 100,000 115,000

• Table 9 Equivalent quantity of excavation



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Gross productivity = 262/100,000 = 2.62 per 1000m2

Adjusted productivity = 262/115,000 = 2.28 per 1000m2

Factors to measure

1. The average distance the material is being hauled over (in km)

2. Whether the haul is all contained within the site or goes on to public roads.(1 = within site, 2 = on public roads).

3. The source of the material.

In situ concrete

General

Separate items are included for different types of pour.

Effort calculation

The amount of effort is calculated as the working time from start to finish on aparticular concrete pour. The figure includes time preparing for the pour, thepour itself and any time required to finish the concrete and repair any cracksetc. The time excludes meal breaks and curing time for the concrete.


Not applicable.

Sizing factors

None.

Factors to measure

1. Indicate the type of pour (1 = Concrete pump; 2 = Direct from concretemixer, 3 = Manual (using dumper, excavator shovel etc), 4 = Skip andcrane)

Concrete ancillaries

Formwork

General

Separate returns are required for end supports, intermediate supports,superstructure and culvert/underpass main construction.


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Effort Calculation

The effort calculation shall be the total man hours in fabricating, assembling,striking and cleaning/repairing the formwork. The calculation should includethe assembly and striking of any falsework required to support the formwork.

Capability Calculation

Not applicable.

Sizing factors

The time taken to fix formwork of different types is shown below.3

Rough Fair ExtraSmooth

Horizontal 1.00 1.00 1.00

Sloping 1.03 1.03 1.03

Battered 1.08 1.08 1.08

Vertical 1.68 1.68 1.68

Curved 2.25 2.25 2.25

• Table 10 Variation of make and fix time with type of formwork

This has been simplified to three categories:

Type of formwork Correctionfactor

Horizontal, sloping orbattered

1

Vertical 1.65

Curved 2.25

• Table 11 Simplified formwork productivity factors

Formwork quantities will be converted into equivalent horizontal formworkquantities.

Example:

3 Source: Harris, EC (1996) CESMM3 Price Database 1996/7, London: Thomas Telford


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Type of formwork Measured Qty,m2

Horizontalequivalent, m2

Horizontal, sloping or battered 17 17

Vertical 299 501

Curved

TOTAL 316 518

• Table 12 Calculation of equivalent quantities of formwork


Gross productivity = 320/316 = 1.01 hours per m2

Adjusted productivity = 320/518 = 0.62 hours per m2

Factor to measure

1. Where is the formwork manufactured? (1 = on-site, 2 = off-site)

2. How many times on average is formwork re-used?

Reinforcement

General

Separate returns are required for end supports, intermediate supports,superstructure and culvert/underpass main construction.

Effort Calculation

The effort calculation shall be the total man hours in handling and fixing ofreinforcement. The calculation shall include all effort from the arrival of steelon site to the start of the concrete pour. The time shall include time waiting fordeliveries, information etc but exclude meal breaks.

Capability Calculation

Not applicable.

Sizing factor

1. The nominal size of the reinforcement bars.

The time taken to fix reinforcement is proportional to the mass per unit lengthof the reinforcement. If the standard nominal size of the reinforcement bars istaken to be 20mm, then the quantity of reinforcement can be adjusted to anequivalent quantity of 20mm nominal size reinforcement.

The equivalent quantity of 20mm nominal size reinforcement is thencalculated as:


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( ){ }q q dd a m mm

m20

202

201= ��

�� + − .................................. Equation 1

Where,m - the mass per kg of the steel actually fixedm20- the mass per kg of 20mm nominal size steelq - the quantity of steel actually fixed.q20 - the equivalent quantity of 20mm nominal size steel.dm - the nominal size of the steel actually fixedd20 - the nominal size of the default reinforcement (20mm)

Example:

Nom Size, mm Qty, tonne Mass, kg/m Qty (20mm), Tonne

10 4.3 0.62 7.00 16 2.4 1.58 2.68 20 1.3 2.47 1.30 32 2.4 6.31 2.09

TOTAL 10.4 13.07


Gross productivity = 98/10.4 =9.42 hours per tonne

Adjusted productivity = 98/13.07=7.50 hours per tonne

Factor to measure

1. Is the steel delivered JIT?

Drainage pipes

General

The measurement will include all activities related to drainage installation,including excavation, supporting of trenches, installation of pipes, backfillingand testing.

Effort measurement

The effort will be the total working time of each gang that is advancing asingle line of drainage. Working time shall include any time waiting forpreceding activities, but will not include meal breaks or breaks due to weatherconditions.


Not applicable.


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Sizing factors

1. Nominal bore, mm

2. Depth to invert, m

The time taken to lay a carrier drain varies linearly with the nominal bore ofthe pipe and the depth to invert. There are four zones in which theserelationships hold:

1. Small, shallow pipes (nominal bore < 450mm, depth < 3m)

2. Small, deep pipes (nominal bore < 450mm, depth > 3m)

3. Large, shallow pipes (nominal bore > 450mm, depth < 3m)

4. Large, deep pipes (nominal bore > 450mm, depth > 3m)

For each zone, the time taken to lay a drain can be expressed as:

t t a d b hnom nom= + +0 . . ......................................................... Equation 2

Where,dnom - the nominal depth in metres

hnom - the nominal pipe diameter in mm.

The equivalent quantity of nominal sized pipes, is then given by the following:

( ) ( ){ }q q a d d h hnom nom nom= + − + −1 ................................. Equation 3

Length,m Depth, m Diameter, mm Length of nominal pipe,m

100 300 1.75 80100 375 2.5 87.5200 167.5


Gross productivity = 16/200 = 0.08 hours per m

Adjusted productivity = 16/167.5 = 0.10 hours per m

Factor to measure

1. Type of excavation (1 = hand, 2 = excavator, 3 = trencher)

2. Type of material.

3. Type of support to pipes (1 = concrete bed, 2 = concrete bed + surround,3 = granular bed, 4 = granular bed + surround, 5 = granular bed + haunch,9 = other)


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4. Type of pipe (1 = clay, 2 = concrete, 3 = iron, 4 = steel, 5 = PVC, 6 = GRP,7 = polyethylene, 9 = other)

Pipework - Manholes

General

The depths of manholes shall be measured from the tops of covers to channelinverts of base slabs, whichever is lower.

Effort measurement

The measurement will include all items, including excavation, installation ofthe manhole, installation of pipework and fittings and backfilling.


Not applicable.

Sizing Factors

1. Internal diameter of the manhole, D

2. The depth of the manhole, h.

The time taken to install the manhole is found to be a function of the volume,

V D h= π 2 * ............................................................................ Equation 4

Where,D - the internal diameter of the manhole, mmh - the depth of the manhole, m

The time taken to install a manhole is then,

( )t a V Vnom= + −1 ................................................................... Equation 5

Where, Vnom is the volume of the standard manhole.

The equivalent number of nominal sized manholes, is then given by thefollowing:

( )( )q q a V Vnom nom= + −1 ...................................................... Equation 6

Depth, m Diameter, mVolume, m Number of nominal tan

Working time = 7.3 hours

Gross productivity =7.3 hours per manhole


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Adjusted productivity = 7.3/ = hours per manhole

Factor to measure

1. Type of manhole (1 = Brick, 3 = In situ concrete, 5 = Precast concrete, 9 =Other)

Piles

General

The length of piles shall be those required, from the cut-off level to the toelevel.

Effort calculation

Will include all operations including setting up the rig, boring, reinforcement,placing of concrete and breaking down any excess. Working time shall be thetotal working time on the pile including breakdowns and waiting for materialsbut excluding meal breaks and breaks due to weather.


Not applicable.

Factor to measure

1. Number of piles.

Roads and paving

Sub-bases, flexible road bases and surfacing

General

A typical cross section of a road pavement is shown in Figure 2. The cappinglayer is only required if the subgrade is weak.


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There are two variations of interest; rigid pavement construction andcomposite construction (Error! Reference source not found.).

Effort Calculation

The effort calculation will be carried out for the gang of men and machinesthat are advancing a single line of road. In the case of flexible road layers thiswill probably correspond to a paving machine. In the case of the rigidpavement this will correspond to a concrete train.


The capability calculation will be based on the rated output of the pavingmachine or concrete train.

Sizing factor

1. Depth of the road layer, mm

The time taken to lay a m2 of roadworks and paving is proportional to thedepth of the layer.

t ad= ...................................................................................... Equation 7

If the nominal depth of a road layer is dnom, then the equivalent quantity ofnominal depth roadworks and paving is given by the following:

q qd

dnomnom = ...................................................................... .Equation 8

Example:

Base course nominal depth is 50mm.

Road surfaceWearingcourse

Subgrade

Base course

Roadbase

Sub-baseFormation

Capping

Formation

Surfacing

Pavementfoundation

Pavement

• Figure 2 Typical cross section of a road


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Return, nominal depth is 75mm. Quantity is 1000m2.. The equivalent quantityof 50mm base course is 1500m2.

Working time = 7.3 hours

Gross productivity =7.3 hours per 1000m2

Adjusted productivity = 7.3/1.5 = 4.9 hours per 1000m2.

Factor to measure

1. The actual width of the road

2. The actual depth of the layer.

Road surfaceWearingcourse

Subgrade

Base course

Roadbase

Lean-mix

Capping

Formation

Surfacing

Pavementfoundation

Pavement

Figure 3 Composite construction

Road surface

Subgrade

Concrete

Sub-base

Formation

Surfacing

Pavementfoundation

PavementPolythene

Reinforcementmesh

• Figure 4 Rigid construction


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Results from pilots

The need for sizing items

The pilots showed up difficulties in the original concept. The list ofconstruction activities was initially based more directly of CESMM. Thisproved problematic for the following reasons:

1. Site data collection did not generally go down to the required level ofdetail. Increasingly site data collection is based on the activities on theproject plan. These would have items such as fix formwork on abutment.There was no way to separate data amongst the different types offormwork in CESMM.

2. Using the CESMM definitions led to a list of 55 construction activities thataccounted for about 80% of the value of the standard project. Whenvisiting other sites it was impossible to get returns on all 55 due todifferences in the designs.

Sizing items have two main advantages:

1. They allow the data to be collected at a level that suits the sites - resultingin returns on only about 30 construction activities.

2. They allow the data to be adjusted for differences in the designs ondifferent sites so that a like for like comparison of performance can bemade.

General difficulties in obtaining data

Whilst sizing items helped a great deal in the development of the method, therewere still difficulties with the quantity and quality of data on site. Theinformation required by the benchmark method is all available on site to somedegree. However, it is often fragmented amongst different individuals -engineers, quantity surveyors, accountants etc. Sometimes differences in theway that these different groups collect data makes it difficult to combine thedata in the way that we require.

There is also a difficulty with obtaining consistency with respect to theproductive units. When counting hours on an activity like formwork, somesites only included carpenters hours, whilst others included carpenters andlabourers. Similarly, on plant intensive activities it is often difficult to extractthe hours for the productive units from the general plant hours.

As a result the amount of that can be achieved with historic data may belimited. It may be necessary to work only with live sites, training site personnelin the benchmark method.


25

Conclusions

The standard new road project has proved that the principles adopted by ACIfor benchmarking civil engineering projects can be applied in practice.However, pilot trials have highlighted difficulties with both the design of themethod and its implementation. Having learnt from these experiences ACI isnow ready to roll out the method on a wider scale and will be looking forprojects to benchmark over the next few years, in order to build up acomprehensive picture of the relative performance of civil engineeringprojects. This information will then be used to derive guidelines about bestpractice in civil engineering.


26

Annex A - Derivation of sizing items for manholes

The data in the CESMM price book was put into a table. Several attemptswere made to find a physical characteristics of the manhole that varied linearlywith the time taken to install a manhole. It was found that the time taken variedwith the ‘volume’ of the manhole, calculated as follows:

VD

h= π2

4................................................................................... Equation 9

A regression analysis was carried out on the data to determine the relationshipbetween the production time and the volume. The results are shown in Figure5.

X Va ria ble 1 Line Fit P lot

0

5

10

15

20

25

- 10.00 20.00 30.00 40.00

V olum e of m anho le (m 2)

Labo

ur G

ang

Hou

rs

Y

Predic ted Y

• Figure 5 Labour gang hours versus manhole volume

The relationship was then normalised around the time taken to install a1200mm diameter, 3m deep manhole. The resulting equation is given by theequation:

tt

tt

at V

nom nom nom= +0 ..........................................................Equation 10

But, we know that t = tnom when V = Vnom, so the equation can be rewritten asfollows:


27

{ }tt

at V V

nom nomnom= + −1 .............................................Equation 11

Rather than adjust the working time, it is better to adjust the quantityproduced to achieve the same effect. That is the actual quantity of aproduct is modified to give an equivalent quantity of the nominal sizeproduct. It is this nominal equivalent quantity that is used to determine theproductivity of the project. I.e.

( )Q Q at V Va

nomnom= + −�

��

��

1 ............................................Equation 12

Where Qa is the actual quantity produced and Q is the equivalent quantityof the nominal sized product.

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