Planning Portal

Transport Assessment
Stage 1: Assessing the Travel Characteristics of a Development: Trip rate

Two technical terms should be understood:
  • “Trip generation” refers to trips which enter and leave the particular development.
  • “Trip rates” refer to the intensity of travel due to the development and are defined in terms of:
    • the number of trips in comparison to the “size” of the development (for example floor area or number of employees); and
    • for a particular time period (for example peak hour or weekday).
The selection of a trip rate is important in estimating the travel generation of a site. The following factors need to be taken into account in selecting a rate for the size of the catchment;
  • the propensity to walk/cycle;
  • the type, quality and frequency of public transport provision;
  • the level of on-site parking restraint;
  • whether there are parking controls in the vicinity of the scheme;
  • the potential for linked trip opportunities; and
  • for retail sites, competition within the locality.
In preparing Transport Assessments it is important to consider a wide range of trip  rates.  Depending on the nature of the development it is likely that a lower (50th) or a higher (85th) rate will be appropriate for most developments.  Care must be taken when using the lower rate, that lower car use can actually be achieved. All rates used will need reasonable explanation and justification in the Transport Assessment.
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