Transport Assessment

A Transport Assessment covers 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 Conditions

  • 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

Proposed Development

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 Updated February 2019) 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.

Assessment Years

  • 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

Assessment Period

  • Weekday AM and PM peak periods
  • ‘With development’ and ‘without development’
  • Weekend peak periods if retail or leisure uses are proposed

Development Generation

  • 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 transport 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, Manual for Streets 2: Wider Application of the Principles 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.

Require Assistance with a Transport Assessment?

Sanderson Associates have extensive experience in providing Transport Assessments, Transport Statements and Travel Plans 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 Transport Assessment Services, please call us on 01924 844080 or click here to complete our secure online form.

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