Stage 1: Assessing the Travel Characteristics of a Development: Person-trip travel surveys
It is important to undertake a person-trip based assessment for all developments for which a detailed Transport Assessment is required. The main sources of person trip data in Northern Ireland are currently the Travel Survey for Northern Ireland, the Census and other local movement surveys. However, these surveys are not primarily designed for use in Transport Assessments and should be used with care.
- The Travel Survey for Northern Ireland (TSNI) contains detailed information and can be useful for estimating trip generation from housing developments. However, it records journey purposes (such as "shopping") rather than trips to development types (e.g. "corner shop", "supermarket", or "town centre"), and it cannot be used for detailed local analysis.
- The Northern Ireland Census 2001 deals with home-based work journeys only, and records only the mode of travel for the main part of the journey. This can obscure information which is of use in a Transport Assessment, such as the mode used to leave or arrive at a development.
- Local movement surveys can vary in their value depending on the purposes for which they have been carried out and the detail included.
A major benefit of the TSNI and the Census is that there is information on all modes, in contrast with the focus on car use that is common in vehicle databases. However, the TSNI and Census cover trips from housing, so a likely difficulty will lie in estimating trips to and from other land uses - although this can be overcome. Developers are recommended to enquire as to the availability of local data.