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 – to understand if there is a baseline transport affect or if there are any restrictions in place e.g. Air Quality Management Areas (AQMA) etc.
  • Existing site use and means of access – to determine if there are any existing constraints or where new access is required;
  • Baseline transport data – to determine the existing traffic conditions for all modes of transport;
  • Public transport assessment – to identify existing provision, capacity and infrastructure;
  • Walking / cycling assessment – to identify existing provision and or existing nominated routes and help determine if and what enhancements are required;
  • Road network assessment – looking at existing conditions, capacity, destinations, speed limits, parking restriction etc.
  • Traffic data and traffic forecast - to determine if there is current spare capacity in normal traffic flow conditions on the network;
  • Safety considerations and accident analysis – obtaining and analysing the Personal Injury Accident Data for the most recent 3 year period (or 5 years if considered appropriate); and
  • Committed developments nearby and their likely traffic generation – to determine if there are any foreseeable capacity issues.

Proposed Development

A detailed description of the proposed development usage including:-

  • Site plan – showing site location, layout and use;
  • Description of proposed land uses – residential, industrial, leisure, retail or multi-functional etc.
  • Scale of development – Numbers, gross floor area (square meterage), expected visitor numbers;
  • Site area;
  • Hours of operation – a weekly profile of normal working hours, extended openings times etc.
  • Proposed access location and design – arrangements, location and method of linkage to existing infrastructure for all modes of transport;
  • Servicing arrangements – routes & facilities for service vehicles (bin wagons, deliveries etc.);
  • Traffic impact of site construction works – abnormal loads & decommissioning etc.
  • Proposed parking strategy – for all developments;
  • Development phasing (where applicable); and
  • Changes to Traffic Regulation Orders.

Compliance with Policy

This normally comprises of the following:-

  • An overview of the proposals compliance with relevant national (NPPF plus other national policies) and local policies on planning (usually the Local Development Framework) and transportation (typically the Local Transport Plan); and
  • 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) at paragraph 108, which seeks to promote the use of sustainable transport in the development process. It ensures that consideration has been given to: -

  • Appropriate opportunities to promote sustainable transport modes can be – or have been – taken up, given the type of development and its location;
  • Safe and suitable access to the site can be achieved for all users; and
  • Any significant impacts from the development on the transport network (in terms of capacity and congestion), or on highway safety, can be cost effectively mitigated to an acceptable degree.

Assessment Years

The Transport Assessment will typically take a view of how the impacts will be felt over several time periods:

  • The planning application year;
  • The opening year of the development;
  • A minimum 5 year design horizon for the local transport network; and
  • A minimum 10 year design horizon for the strategic road network where it has an impact on the SRN.

The appropriate horizon assessment should be agreed with the relevant authorities during pre-application consultations.

Assessment Period

The traffic assessment is typically carried out during peak periods, i.e. during rush hours or at peak periods at the weekend.

  • Weekday AM from 7:30 to 9:00 and PM from 3:00 to 7:00 dependant on the location and surrounding facilities (if there is a school facility etc.);
  • ‘With development’ and ‘without development’; and
  • Weekend peak periods if retail or leisure uses are proposed typically 11 – 4pm.

Development Trip Generation

  • Quantifying the impact of the development on the Transport network by all modes based on an estimate of person trips. The TRICS database contains local and national trip rate 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; and
  • 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 an impact on the highway network, the level of impact at all critical locations should be established through assessments and modelling. There are various computer modelling packages used, some in isolation and others as part of larger modelling requirements, such as;

  • PICADY – predicts capacities, queues, delays and accidents at isolated priority junctions;
  • ARCADY– predicts capacities, queues, delays and accidents  at roundabouts;
  • JUNCTIONS -  modelling and analysis for roundabouts. priority junctions and signalised junctions;
  • LINSIG – a design and assessment tool for traffic signal junctions and urban networks; and
  • LINSIG and TRANSYT – for linked signalised junctions.

PICADY and ARCADY now form part of the JUNCTIONS 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 measures proposed 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, for example: -

In respect of the Strategic Road Network any proposed mitigation measures should provide comparable capacity 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 a competitive fee proposal for the provision of our Transport Assessment Services, please call us on 01924 844080 or click here to complete our secure online form.

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