A Transport Assessment is a comprehensive and systematic process that sets out various transport issues relating to a proposed development. It identifies what measures will be taken to deal with the anticipated transport impacts of the scheme in relation to all forms of travel. National guidance recommends an iterative approach to the assessment where as a first step the improvement of accessibility and encouragement to use sustainable travel should take precedent over measures to increase traffic capacity and increased use of vehicles. Notwithstanding, the above safety and congestion are key issues which must be addressed in the report.
In some cases, the transport issues arising out of development proposals may not require a full Transport Assessment. In these instances a simplified report in the form of a Transport Statement may be more appropriate.
Following the withdrawal, in October 2014, of The Department for Transport Document (March 2007) ‘Guidance on Transport Assessment’ guidance on the preparation of supporting documentation in highway assessment terms can be found in the Planning Practice Guidance (PPG) suite of documents and in particular in “Travel Plans, Transport Assessments and Statements in decision taking”. This guidance is intended to assist all stakeholders in determining whether an assessment may be required and, if so, what level and scope that assessment should include.
For major development the Transport Assessment is normally accompanied by a Travel Plan, which is a report containing a package of measures tailored to the transport needs of the development aimed at increasing travel choices and reducing reliance on the private car.
Travel Plans are typically requested to accompany planning applications when the scale of a development meets with the threshold requiring a Transport Assessment. However Travel Plans can also be requested for extensions to existing developments; where car parking issues are present, where the Local Council perceive the need of such a plan or where the applicant seeks to improve the environmental image of their business.
The requirement for a Transport Assessment/Transport Statement and Travel Plan are site specific but are generally required to be submitted in support of a planning application when developments exceed certain thresholds provided on the Planning Portal.
These thresholds are for guidance purposes and should not be read as absolutes as some parts of the local highway network will be more sensitive to change than others. Early pre-application consultation with the relevant Highway Authorities is strongly recommended to determine the level and scope of the assessment that may be required. Depending on the scale of the development pre-application consultations often involve submitting a Transport Scoping Study to the Local Highway Authority to formally agree the level and scope for the Transport Assessment.
The guidance reflects the Government's policy to reduce the reliance on the private car and to improve accessibility by other sustainable means of transport.
Transport Assessments, and to a lesser extent Transport Statements, are required to identify the impact on the entire transport system in the vicinity of the development. This means that ‘person trips’ by all modes of transport to/from the development are considered and not just vehicle trips on the local road network. This requires a multi-model assessment which can involve using recent census data and also the TRICS database for different modes of travel. Where an extension to an existing use is proposed or housing in a residential area it may be the case that a survey of the present levels of traffic generation or those of an adjacent site with a similar use are required.
Within the Transport Assessment, developer funded mitigation measures are required to be identified to accommodate these ‘person trips’ where detrimental development impact or existing deficiencies in infrastructure have been identified. Such measures are usually secured through “Grampian planning conditions", or binding legal agreements such as a Section 106 Planning Agreement (Town and Country Planning Act) followed by a Section 278 Highways Agreement (Highways Act) to deliver the improvement. These agreements may include a requirement to fund and carry out the improvement work or a financial contribution towards an Authority lead initiative.
Developments are now constantly being encouraged to reduce the amount of vehicle traffic they will generate through the introduction of non car infrastructure improvements and services. As such many Local Planning and Highway Authorities have a Unitary Development Plan or Local Development Framework approval to a district wide contribution by the developer to measures to improve public transport. These contributions are linked to a formula devised by the Local Planning Authority/Local Highways Authority where the level of contribution is linked to the additional vehicle movements generated by the development.
Transport Assessments cover major developments where the traffic or person trip impact is significant in both volume and area of impact. The Transport Assessment will include an audit and appraisal of the following:
- Existing site information
- Existing site use and means of access
- Baseline transport data
- Public transport assessment
- Walking / cycling assessment
- Road network assessment
- Traffic data and traffic forecast
- Safety considerations and accident analysis
- Committed developments and their likely traffic generation
A detailed description of the proposed use including:-
- Site plan
- Description of proposed land uses
- Scale of development
- Site area
- Hours of operation
- Proposed access location and design
- Servicing arrangements
- Traffic impact of site construction works
- Proposed parking strategy
- Development phasing (where applicable)
- Changes to Traffic Regulation Orders
Compliance with Policy
This normally comprises of the following:-
- An overview of the proposals compliance with relevant national and local policies on planning and transportation
- An overview of any relevant planning decision which may impact on the proposal in a policy sense
Appraising the Impact of the Proposed Development
The potential impacts of the development proposal should be assessed against the principles of the National Planning Policy Framework (NPPF) which seeks to promote the use of sustainable transport in the development process and requires plans and decisions to take into account whether:-
- The opportunities for sustainable transport modes have been taken up depending on the nature and location of the site, to reduce the need for major transport infrastructure.
- Safe and suitable access to the site can be achieved for all people; and
- improvements can be taken within the transport network that cost effectively limit the significant impact of the development.
- Development should only be prevented or refused on highways grounds if there would be an unacceptable impact on highway safety, or the residual cumulative impacts on the road network would be severe.
- Planning application year
- Opening year of the development
- Minimum 5 year design horizon for the local transport network
- Minimum 10 year design horizon for the strategic road network
- Weekday AM and PM peak periods
- ‘With development’ and ‘without development’
- Weekend peak periods if retail or leisure uses are proposed
- Quantifying the impact of the development on the Transport system by all modes based on an estimate of person trips. The TRICS database contains local and national trip rates measures for typical land use sites. Local surveys may also be required in specific cases.
- Calculating vehicle trip generation depending on the type of development e.g. retail can have a significant effect on vehicular traffic patterns
- Adjustment of development vehicular trips to take account of access by non car modes
- Trip distribution and assignment using existing traffic flow patterns or a gravity model. A gravity model is an assessment technique that uses population within geographical zones as a proportion of the total population within a catchment area to give a likely proportion of trips to/from the development site by highway route. With some developments the planning assessment of other competing uses can be used in the gravity model.
Transport Impacts and Mitigation Measures
If the Transport Assessment confirms that a development will have a material impact on the highway network, the level of impact at all critical locations on the network should be established through assessments and modelling. There are various computer modelling packages such as;
- PICADY – for major/minor priority junctions
- ARCADY– for mini and larger roundabouts
- JUNCTIONS 9 - for non-signalised junctions
- LINSIG – for signalised junctions
- LINSIG and TRANSYT – for linked signalised junctions
PICADY and ARCADY form part of the JUNCTIONS 9 software suite which is utilised for junction capacity modelling assessment.
Where mitigation measures are proposed the Local Planning or Highway Authority will require that appropriate conditions are attached to any planning permission granted and/or Section 106 / 278 agreements entered into to deliver the improvements.
In all cases the transport mitigation plan or package of measures should focus on maximising access by sustainable travel to the development.
If the mitigation measures require physical improvements to the highway network, the development should ensure that appropriate design guides and parameters are used, e.g. Design Manual for Roads and Bridges, Manual for Streets and any appropriate Local Highway Authority standards. A Road Safety Audit may also be required.
In respect of the Strategic Road Network proposed mitigation measures should provide capacity that is comparable to the general capacity of that part of the existing network and not, for example, seek to produce a junction with significantly more capacity than the surrounding road network.
Transport Statements cover the smaller scale developments where the traffic impact is limited in both volume and area impact. The Transport Statement will generally include an audit and appraisal of the following:
- Existing site information
- Baseline traffic data
- Existing site use and means of access
- Proposed land use and scale of development
- Proposed means of access
- Person trip generation and distribution of trips by mode of transport
- A qualitative and quantative description of the proposed travel characteristics of the proposed development
- Proposed improvements to site accessibility by sustainable modes of travel
- Proposed parking and servicing strategy
- Residual vehicle trip impact
- Transport implications of construction traffic (if there are specific local difficulties identified)
- If the development site has a current use or an extant planning permission, the net level of change in traffic flows that might arise from the development is calculated and considered
What Our Clients Say:
Swept Path Analysis and Visibility Drawing incorporated into a Technical Note, Proposed Residential Dwelling, Colchester.
Highway Statement, Proposed Residential Development, Stockport
Transport Assessment, Proposed Residential Development (170 dwellings), Essex
Speed Survey, Proposed Private Residential Development – Testimonial
Access Feasibility Study, Proposed Private Residential Development – Testimonial
Analysis of Speed Survey and Swept Path Analysis
Stage 2 Road Safety Audit, Residential, Staffordshire
Construction Traffic Management Plan
Flood Risk Assessment, Testimonial, Industrial Development, Sheffield
Require the Services of a Highway Engineer?
Sanderson Associates have enjoyed over 36 years in business delivering experienced Highway Engineering Services to our clients, having completed over 12,200 schemes for a wide variety of major and minor developments throughout the whole of the UK, Isle of Man and Ireland.
We would be pleased to provide you with our competitive fee proposal to provide you with our Highway Engineering Services, please call us on 01924 844080 or click here to complete our secure online form.