Traffic Modelling

Network Management & Information Centre

What is a model?Models are a simplified representationof real life

Why do we model?Modelling is a tool that enables us to:

• Gain a greater understanding of past and present situations• Foresee the effects of altering the current transport network & test

radical solutions• Minimise the potential for planning to go wrong!

S-Paramics Microsimulation• An internationally renowned road traffic

microsimulation modelling package

• Used to analyse present and future traffic conditions

• Real time visual display

• Wide variety of statistical output

• Widely used in Local Authorities

Model BuildModelling Procedure

Calibration

Validation

Option Testing

Model Build

- Site Visits

- Carriageway Dimensions

- Lane Allocation

- TRAFFIC SURVEYS

Model Build

BUS NETWORK

- Bus Station

- Bus Stops

- Bus Routes

Model Build

TRAFFIC SIGNALS

Model Build

CAR PARKS

CalibrationAdjustment of model parameters to reflect real life situations

- Vehicle Routeing

- Junction Capacity

ValidationComparison between observed and modelled flows

Department for Transport acceptability standards

Option Testing

- Quick

- As many schemes as you wish

- Radical ideas

- Excellent statistical output

- Real time visual displays

Option Testing

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Portsmouth Road Southbound

Statistical Outputs:

- Traffic Flows

- Journey Times

- Queue Lengths

Option Testing

Real Time Visual Display

SCOOT

Splitplit Cycleycle Offsetffset Optimisationptimisation Techniqueechnique

- Co-owned by Peek Traffic Ltd, Siemens Traffic Controls and TRL Ltd

- Used in > 200 cities in UK & Worldwide

- Adaptive traffic management method which minimises traffic problems, especially congestion

SCOOT

Splitplit Cycleycle Offsetffset Optimisationptimisation Techniqueechnique

- Online computer continuously monitors traffic flows over whole network and optimises signal timings to decrease delay and improve traffic flow

www.scoot-utc.com

Surrey’s UTC SCOOT System

22 pelican crossings

110 junctions

Epsom

Ewell By-PassKingston Road

Esher

SunburyStaines

Guildford

Godalming

Woking

Meadows Gyratory

Surrey’s UTC SCOOT System: Regions

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Epsom

Ewell By-Pass

Kingston RoadEsher

SunburyStaines

Guildford

Godalming

Woking

MeadowsGyratory

Surrey’s SCOOT UTC System: Regions

Paramics Model in SCC controlled region

Paramics Model in HA controlled region

GodstoneInterchange

Past Problems with Modelling SCOOTSIMULATING “GATING”

What is Gating?

The control of inflow of traffic into sensitive areas where it is especially important to prevent serious congestion

Used to prevent gyratory systems from being blocked

Past Problems with Modelling SCOOTSIMULATING “GATING”

What is Gating?

- “Gated” links store queues

- “Bottleneck” links are maintained free-flow

When the “bottleneck” links reach a defined saturation, SCOOT gating operates automatically &

reduces green times on “gated” links

Past Problems with Modelling SCOOTMODEL VALIDATION & OPTION TESTING

- Schemes may have been dismissed as unable to work in heavily congested areas under fixed time control

- Sceptical Results?

SCOOT has been shown to decrease vehicle delay by typically 12% over alternative non-adaptive methods

The SCOOTLinkMicrosimulation passes detector

information based on SCOOT signal

timings

SCOOT Micro-simulation

SCOOT passes signal timings

based on detector flow

(Siemens, 2005)

Why SCOOTLink?

- Surrey contains many SCOOT regions

- 8 Regions have S-Paramics Models

- Past experience of simulating SCOOT regions

- Increase functionality & efficiency of S-Paramics

Produce Models that will be a Truer Representation of Real Life

Hampton Court Palace

Case Study: Hampton Court Flower Show

- Annual event in south west London

- World’s largest flower show

- 179,000 visitors each year

Esher SCOOT Region

Case Study: Hampton Court Flower Show

- An additional 21,000 vehicles pass through Esher during the 6-day event

- Peaked nature of traffic flow poses a problem in the town of Esher

Case Study: Hampton Court Flower Show

A3 at Esher Common

-A queue extends back from Esher over 2km to the A3 trunk road

-Between 9am and 12pm the queue reaches the A3 mainline

-This results in erratic driver behaviour and dangerous driving conditions

Esher SCOOT Region

A3 at Esher Common

Hampton Court Palace

Case Study: Hampton Court Flower Show

Strategy DesignStrategy Objective:

To prevent the queue from Esher town centre extending onto the A3 and interrupting the mainline

How?

By the creation of a special event SCOOT UTC strategy which will operate during the flower show

Strategy Testing

- Used a traffic model to test various strategies

- The modelling enabled quick assessment of many strategies within a controlled environment

- It was found that a gating strategy was the most effective which:

Provides more green time for traffic approaching Esher from the A3 when the congestion level here is greater than 10%

- On-street trials were performed

- Unlikely to be perfect, as a model is not a perfect copy of real life!

- Operate 08:00 – 12:00 hours

- Implemented and monitored from the NMIC control room

Strategy Implementation

CCTV

UTCUTC

NMIC

Blooming Marvellous?

- In 2008 it met the study objective with no queuing on the A3 mainline

- Strategy was operated as predicted by the traffic model

- No public complaints

- Its success means that it can now be used for other events, bothplanned and unplanned, which create similar traffic problems

e.g. Sandown Park, A3 road closures due to incidents?

Blooming Marvellous?

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A3 Northbound exit slip at Esher Common