Transport modelling

1. Transport modelling

Buckinghamshire County Council (BCC) has developed a suite of transport models which should be used as part of a Transport Assessment (TA) and form part of a strategy by which the transport models are relied upon as the common forecasting tool for all transport processes.

The process was established to ensure that the development and appraisal of Transport Assessments are carried out in an efficient and effective manner utilising common and sound data inputs. These models encompass the geographic areas of:-

  • Aylesbury Vale
  • Buckingham
  • High Wycombe
  • Buckinghamshire Countywide

These models in simplistic form aim to predict what will happen if we change something to the road or transport network in the County. Data is fed into the model in order to inform us what will happen for example, to traffic patterns if we built a new bypass, a new housing / employment site or make changes to highway infrastructure.

The need for the models

Transport models are very important. Over the next decades, thousands more houses and employment sites will be built across the county to meet the demands of a growing population.

Building houses or employment in an area will ultimately affect travel to / from other areas thereby potentially impacting on large areas of the County’s transport network. This will usually add pressure to existing roads thereby necessitating the need for construction of new roads or other transport infrastructure.

The Buckinghamshire Local Transport Models can assist in planning sustainable locations where housing and employment should be located to minimise this impact whilst at the same time complementing a firm understanding of the impacts of proposed housing growth and transport infrastructure schemes on the environment. The models therefore aim to assist the appraisal of new developments / highway improvements for current as well as future year scenarios through the analysis of:-

  • Traffic flows on particular highway links
  • Link time especially to determine impacts of congestion
  • Routing information
  • Trips for any given year / scenario
  • Mode, destination and time of day choice

2. Junction modelling

A number of junction models have been developed utilising VISSIM modelling software on an ad-hoc basis to consider specific capacity issues or support planning applications.

The cost of developing these models is relatively small. As such, these models are not regularly updated or maintained


Key use:

Designing junction or network improvement

Monitoring traffic behaviour

Visualising impacts

Key inputs:

Traffic flows

Signal timings

Road layout

Traffic behaviour

Outputs available:

Journey times

Queue lengths

Traffic counts

Network statistics

3D modelling

Benefits of use

Modelling interaction between junctions

Illustrating traffic behaviour

Journey time & queue length assessment

3. Local network models

There are a number of local network models that have been developed to represent specific local network conditions within the towns of Buckinghamshire (Aylesbury, Buckingham and High Wycombe). These models have been built utilising VISUM software and which are all based on recent traffic data and are considered to be representative of contemporary traffic conditions.

The models are intended to be used for assessing the traffic impact of highway schemes and new land-use development.


Key use:

Determining changes in routing

Congestion mapping implementing municipal/regional traffic control schemes

Key inputs:

Network properties

Junction properties


Signal timings

Policy tests

Outputs available:

Traffic routing

Congestion data

Emissions data

Integrated signal plans

Queue lengths

Traffic counts

Network statistics

Benefits of use:

Modelling congestion & assessing its wider impact

Optimising multiple signals

Analysing interaction of junctions

4. Countywide Network Model

The Buckinghamshire County wide model aims to complement delivery of Economic Strategies and business case developments by:-

  • Assisting in the appraisal of current and future impacts of infrastructure projects with regard to the performance of Buckinghamshire’s transport networks especially the identification of wider implications for economic, environmental, and social impacts.
  • Assisting the development of quantitative business cases for major infrastructure investments in order to secure capital funding from a range of sources.
  • Assisting the provision of evidence to support the delivery of infrastructure across Buckinghamshire through the application of evidence-based analysis of problems / solutions and high quality presentation of analyses through the use of GIS and web reporting tools.
  • Maximising the benefits from available data and current analytical models through application of relevant, available information sources and interfacing with existing local transport models, including those for Aylesbury, High Wycombe and Buckingham.
  • Providing benefits in the delivery of strategic planning (Local Plans), network management and environmental assessment/monitoring, offering potential benefits across a wide range of Council functions.
  • Supporting major project through statutory planning processes.


Key use:

Analysing major schemes

Illustrating wider changes in flow/delay

Exports into GIS/Spatial systems

Key inputs:

Network data

PT paths


Demand data

Survey data

Outputs available:



Congestion data

Routing info

Public transport ridership

Benefits of use:

Processing large amounts of demographic data

Understanding changes in demand

Exports for economic or environmental assessment


Countywide Model Map

5. Model access

We recommend that modelling should be used for all developments which would impact on the County’s highway infrastructure through their construction.

6. Costs and enquiries

Buckinghamshire County Council charges for the use of their transport models. These models are constructed to complement WebTAG guidelines and where possible are in compliance with modelling standards. Information relating to the models are available upon request. The current charges for model use are shown in the document below. Costs are subject to change.

The modelling team at Buckinghamshire County Council should be the first point of contact in respect to access to the models. The team may be contacted for further information at:

TEE Transport Modelling
Buckinghamshire County Council
County Hall
Walton Street
HP20 1UA

For more information please contact: scraine@buckscc.gov.uk or 01296 383067.