civ3703 - 10b managingroad traffic

8/10/2019 CIV3703 - 10B ManagingRoad Traffic

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CIV3703 Transport Engineering

Module 10Part 2

Managing Road Traffic


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10.7 Traffic Control Signals

Basic Principle: Allocation of green time tovehicle movements in proportion to volumes

entering.

Design (Australia): Austroads Traffic SignalsA Guide to the Design of Traffic Signal

Installations.


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Signal

Source: http://www.miataturbo.net/insert-bs-here-4/random-pictures-thread-only-rule-post-here-more-entertain-me-

54469/page634/


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Basic Design Process

Collection of preliminary data.

Determination of geometric requirements.

Computation of phasing schemes.

Selection of signal displays.Selection of detection system and controller.

Selection of signal hardware.

Preparation of electrical designs, time settings andoperational features.


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Major Components

Signal lanterns

Lantern supports

Power reticulation

Signal controllerTraffic detectors


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10.7.1 Types of Traffic Signal Control

Terms: Signal phasea state of the signals during

which one or more movements receive right

of way.

Signal cycleone complete sequence ofsignal phases.

Intergreen periodthe time taken by acombination of amber and all-red displays.


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A typical phasing at an intersection


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Types of Controllers

Fixed Time ControllersNo detectors

Fixed sequence

Relatively cheap but inflexible

Semi Traffic Actuated ControllersUse detectors on minor approaches

Traffic Actuated ControllersDetectors on all approaches

Responsive to changing conditions


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10.7.2 SIDRA

Signalised Intersection Design and Research Aid

Computer software package originally developed

by ARRB Transport Research Ltd. Aids in the design and evaluation of signalised

intersections, roundabouts and stop sign

controlled intersections.

Widely used in Australia and overseas.


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10.7.3 Co-ordination of Traffic Signals

Urban areastraffic signals may be in close proximity.Traffic operation enhanced if signal sets can be coordinated.

Simplest casesingle arterial road with cross intersection

at constant spacing.

Complex casesnetwork of roads and streets


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Co-ordination of Traffic Signals

Arterial road

Area

Freeway entry


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Task: Coordination of Parameters

Cycle time: All signals within a particular area mustoperate at one common cycle length.

Green split: Relative proportions of the cycle length

must be specified for each phase at each

intersection.

Offsets: Relative timing of signals on main roads

must be such that vehicles travelling along the road

do so with minimum stops and delay.


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Central monitoring System

The SCATS includes production of trafficperformance reports and event/incident reports.

The SCATS Default Configuration will beprogrammed to the following settings:

Maximum number of workstation connections to the SCATS Central Manager = 50

Maximum number of workstation connections to each SCATS Region = 20;

Maximum number of ITS Ports = 15


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System hierarchy


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Australia

STREAMS (Synergised Transport ResourcesEnsuring an Advance Management System) -

Queensland - 17 locations

SCATS (Sydney Coordinated Adaptive Traffic

System)

Computer softwares

HCM&TRANSYT-7F, SYNCHRO, PASSER, SOAP,

NETSIM


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The magic roundabout, Swindon, England
http://localhost/var/www/apps/conversion/tmp/scratch_7//upload.wikimedia.org/wikipedia/commons/2/24/Magicroundabout_hemel.svg


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10.8 Aim of Traffic Management

Definition:The application of a defined traffic control policy to an

area or an extended length of road, with the aim ofachieving a specified set of community objectives.

(Traffic management distinguishable from a trafficcontrol action which applies to a particularintersection or trouble spot).


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Types of Traffic Management Objectives

Improvement of physical conditions, e.g. reductionof congestion

Improvement of physical environment, e.g.

reduction in noise pollution

Improvement of access, e.g. to commercial areas

Improvement of safety, e.g. slowing of vehicles to

improve child safety

Reduction of parking problems


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Implementation

Usually involves alteration of traffic flowpattern.

Some roads will have lower volumes, some

will have higher volumes.Trade-off situation.

Community involvement

Trials


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Traffic Calming

A particular thrust of traffic management.

Objectives usually include:

Reduction of vehicle speeds. Encouragement of calm driving.

Removal of unnecessary traffic.

Enhancement of the environment. Improvement of road safety.


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Levels of Traffic Calming

Level ILocal levelrestrain traffic speeds & lessen impacts

Levels of service and capacity not an issue

(Example: local area traffic management)

Level IICorridor levelrestrain speeds and lessen impacts

Levels of service and capacity important

(e.g., calming of an arterial road section)

Level IIIArea levellessen volumes and impacts area wide

(e.g, reducing travel, reducing speed in particular

at critical locations)


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10.9 Traffic Management Principles

Basic design principle:decide where the traffic is to go,

and where it is not to go,

and apply measures to achieve the desired distributionand flow characteristics.

Defined road hierarchy needed to implement

traffic management.

Each road:

Balance of traffic function and access function.


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Access Vs. Mobility


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10.10 Functional Classification of Roads and Streets

Typical system inBrisbane:

Type A - Access roads (cul-de-

sac, minor roads)

Type B - Collector roadsType C - Distributor roads

Type D - Sub-arterial roads

Type E - Arterial roads

Type F - Industrial roads


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Typical road design criteria for residential areas


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10.12 Major Urban Road Networks

Aim: seek to make travel on major road system as attractive as

possible so as to encourage their use.

Various measures to achieve this.


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Measures to Encourage Travel on Major Roads

Parking bansProhibition on parking

Introduction of clearways

Provide additional traffic

lanes without construction

work (remarking?)

Disbenefit to adjacent

landholders

Require appropriate level of

enforcement


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Access control and reduction Major road traffic has absolute priority

Eg., Stop or Give-Way signs can be used

Limiting number of intersections at which access to the major road is

possible


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Intersection improvementsflaring of approaches

provision of separate

turning lanes

channelisation

turn restrictions

traffic signal installation


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Coordination of traffic signals


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Designation of

heavy vehicle

routes


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When the major roads are consideredas people movers than vehicle

movers, then

Encouraging public transport

operationExclusive right-of-way

Bus priority lanes

Traffic signal priority

Movement ban exemptions

Preferential access to freeways


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10.13 Traffic Management for Residential Areas

Preparation of scheme must be done consideringbig picture.

Local traffic area usually bounded by arterial roads.

Areas generally of residential nature, but may not

be exclusively residential.


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Treatments for Local Areas

Reduction of intersection conflicts by the use of Stopor Give Way signs.


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Reduction of statutoryspeeds.


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Reduction of street

connectivity by full or

partial intersection

closure.


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Reduction of local street connectivity by partial

prevention of access from major roads.


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Discouragement of through traffic by reducing

the width of intersection openings from

major roads.


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Reduction of speeds by changes of road format.


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Discouragement of through

traffic by change of the

nature of street

entrance.


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Reduction of intersectionspeeds by the use of

roundabouts.


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Reduction of speeds by physical speed control devices,

e.g. humps, rumble strips, etc.


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Prohibition of large vehicles.


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10.14 Traffic Management for Rural Roads

Objectives: Capacity(if capacity is a problem then add auxiliary lanes)

Safetyconsistent level of safety along the road is

important (drivers perception of relative safety)

Quality of service - linked to safety


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End Module 10

civ3703 - 10b managingroad traffic

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