What is Transport Modelling
What is the purpose of a transport model?
Understanding how to connect people and places in terms of where people will live and how and where they may work in the future is crucial for planning transport infrastructure, services and initiatives to enable the development of healthy and sustainable places. Transport models are a tool to test scenarios that, in turn, will help planners and developers understand any impacts and opportunities in order to make informed policy decisions.
What is transport modelling?
A transport model is a detailed digital replica of the complex real-world transport and land use systems. The model is a set of mathematical relationships to represent the choices people make when travelling. These choices include how many trips to make, the timing of those trips, the selected route, their origin and destination and the mode used. Travel demand is the combined effect of thousands of individuals making these choices.
Transportation modelling is not limited to vehicles and is multimodal (e.g. walking, cycling, bus and rail). All modes of transport and their interactions can be modelled. Transport models must follow the government's Transport analysis guidance (TAG).
What can Transport Models be used for?
The outputs from Transport Models can help to:
- provide part of the transport evidence for Local Plans and planned development within the respective areas;
- understand and mitigate the impact of external influences e.g. housing allocations, National Highways schemes;
- inform Business Case submissions to secure Government funding for new infrastructure and maintenance;
- provide evidence to support responses to Government consultations;
- support the development consent order and the town and country planning process on key schemes;
- understand suitable phasing of maintenance and utilities work to manage congestion impacts;
- optimise the performance of the existing transport network;
- inform accessibility planning for key land uses; and
- allow for the assessment of new public transport schemes or priorities.
What can Transport Models Do?
Within a model, future scenarios for population growth, land use, transport networks and travel behaviour can be built to assess the impact of these changes. Transportation modelling tools enable modelling experts to develop different scenarios for a transport network and test them under a range of assumed future demographic, infrastructure or economic conditions. Transport models can:
- forecast the number of trips on a specific area’s road network;
- project long-range traffic growth patterns;
- highlight the forecast traffic impacts of proposed new land use developments;
- evaluate the effectiveness of various transport project scenarios;
- test policy implications of travel mode choice (Travel Demand Management);
- help local authorities find ways to mitigate current and future traffic capacity constraints.
What are the Model Outputs?
The outputs (modelling results) can be used in a variety of ways and provide technical evidence to support the consideration of future circumstances. Results can be presented in a variety of ways and appropriate to the evidence requirements needed. They would typically involve:
- link flow
- volume of traffic over road’s capacity
- difference plots
- average delay
- specific select links to understand distribution
Additional outputs could include:
- junction turning count information – if appropriate validation checks have been undertaken beforehand
- cordon matrices, which could be generated to feed into microsimulation models where they exist or are being used for the development
- technical note setting out the methodology and assumptions used
- presentations
When should a transport model be used?
Before any detailed modelling is undertaken, there is a requirement to consider a range of plausible scenarios that would help contribute to delivering the overall vision for transport for the area. In alignment with draft East Sussex Local Transport Plan 4 2024-2050, and the road user hierarchy, particular attention should be given to opportunities to reduce travel and enable access by walking, wheeling, cycling and public transport before private car use. The early stages of any master-planning process should therefore identify the opportunities for travelling sustainably to key destinations and identify potential ways of maximising those opportunities before proceeding with modelling work.
Once access proposals have been developed a model test should be used to confirm whether the access arrangements and other mitigation measures are workable and whether the residual number of vehicle trips can be accommodated on the highway network without causing impacts on sensitive locations such as Air Quality Management Areas (AQMAs) or critical junctions (which affect the operation of the wider network). A model test is needed to help the highway authority to assess whether the impacts of the development (once sustainable access has been identified) can be sufficiently mitigated.
Generally larger scale developments, those with a complex mix of uses or those in sensitive locations (e.g. near AQMAs, or in areas with high existing congestion levels) will require area-based modelling so that the Highways Authority can assess the impacts of the development on the surrounding transport network.
For smaller developments in less sensitive locations where the Highways Authority deems that the development does not require strategic modelling, then localised modelling may be sufficient to assess the localised impacts in the immediate vicinity of the development. Judgement on whether a development proposal would require, or would benefit from, transport modelling is at the discretion of toe Highway Authority and will be decided on a case by case basis.
Before commencing any modelling work it is recommended that a developer contacts ESCC to understand the key requirements and in order to scope out the necessary modelling work. This is best undertaken through the ESCC pre-application advice service.
The East Sussex Countywide Transport Model (CWTM)
The East Sussex Countywide Transport Model (CWTM) has been developed to help in the assessment of the likely transport impact arising from new development proposals and other changes to transport infrastructure. The CWTM is the key transport planning tool to inform current and future transport patterns and demand across East Sussex. Further detail on the CWTM and the protocol for accessing the model are linked below.
- East Sussex Countywide Transport Model – Overview
- East Sussex Countywide Transport Model – Access protocol
Contact us
Email - developmentcontrol.transport@eastsussex.gov.uk
Telephone - 01273 482 254