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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?
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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