Transport Assessment & ModellingPrinciples and Practice

Daws Hill Reference Group9th January 2012

Richard Smith, Technical Director, Jacobs

Transport Assessment Process

Existing Transportation Conditions

Local knowledge

Data collection Transport supply and transport demand

Traffic volumes Vehicle classification Traffic speeds Journey times Queue lengths

Origin – Destination patterns Pedestrian/cyclist volumes Public transport movements Driver behaviour Junction capacity (saturation flow)

Trip Generation from New Developments

Fundamental process in any Transport Assessment

Two key methods:Appropriate local surveys and/or TRICS

Vast database of observed traffic surveys at developments

6,290 survey days at 3,742 sites

Suburban Area

Free Standing

Edge of town

Neighbourhood centre

Edge of town centre

Town centre

TRICS – How is it used?

Type Composition Area/Size Location Density Car Parking Affordable % Car ownership etc

Guidelines

Overall TRICS® is an information service. It does not provide direct answers to transport assessment questions. Instead, it provides its users with a system of trip generation ranges, with users needing to take into account all appropriate error margins when presenting their findings. The careful use of TRICS®, in line with this guidance, will help practitioners make better informed judgements.

Interpretation

Judgement

Traffic Forecasting

Establish Future Transportation Conditions

TEMPRO software Policy based growth (land

use) Trend based growth (socio-

demographic factors)

High Wycombe – around 15% traffic growth forecast by 2026

National Trip End Model

‘Base Year’

‘Forecast Year’

‘Do Minimum’ ‘Do Something’

Transport Modelling: The right tool for the job

Micro simulation Junction models

StrategicModellingInter-urban

Road and rail

Development? New local road?

Bus priority? Improve Junction?

Pla

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Strategic Modelling - VISUM

Strategic Modelling - VISUM

Planning urban / inter-urban transport systems

Less detail, more ‘big picture’ Average conditions over the

typical peak hour

Number of lanes Capacity Free-flow speed

Model Development

MODEL

INPUTS

Road network

Signal settings

Bus network and stops

Travel information

Socio-economic data

Land use Observed flows

Observed journey times

Observed behaviour

CHECKS

OUTPUTS

Traffic flows on the network

Public transport patronage

Travel demand between areas

Journey times along routes

Microsimulation Modelling

Localised detail Performance changes

through peak hour Vehicles respond to

‘real world’ Scheme promotion

Junction Modelling

Isolated Junctions ARCADY PICADY LinSig

Linked Junctions TRANSYT

Network Performance- Total Travel Time- Total Delay- Average Speed

Analyse Model Output

Journey Times- General Traffic- Buses

Traffic Volumes- Link Flows- Turning Movements- OD Matrices- Flow Diagrams

Junction Performance- Delays- Queue Lengths- Relative Congestion Levels

3D Presentation

Link SpeedsTransport AssessmentInterpretation

Judgement

Daws Hill Reference Group9th January 2012

Richard Smith, Technical Director, Jacobs

Questions and Discussion

Transport Assessment & ModellingPrinciples and Practice