Trip generation and TRICS.
Trip generation that stands up: TRICS selections the officer can follow, multi-modal trip rates and honest comparisons with existing use.
Also known as: trip generation, trip rate, TRICS, trip rates, multi-modal trip generation
What’s included.
Trip generation estimates how many people and vehicles a scheme will generate. TRICS, the national trip rate database, is the usual source. Officers look closely at which sites were selected, so a clear, defensible selection matters.
- TRICS site selection and filtering
- Multi-modal and vehicle trip rates
- Peak hour and daily trips
- Existing or fallback use comparison
- Mode share from Census data
- Sensitivity tests
Straightforward, proportionate, agreed early.
Defensible
Site selections explained so the officer can check them.
Multi-modal
People trips by every mode, not just cars, as national policy expects.
Fair comparison
Credit for existing or fallback uses where it is justified.
Questions we get asked
What is TRICS?
The national database of trip rates from surveyed developments, used by most highway authorities.
Can we take credit for the existing use?
Often, if the existing use is lawful and could continue. We set out the comparison clearly.
Do you use Census data?
Yes, for mode share and journey-to-work patterns, alongside TRICS.
Often needed alongside.
Choosing trip rates that stand up
TRICS is the database of traffic surveys at existing developments in the UK and Ireland. Trip rates for a new scheme are drawn from comparable surveyed sites, so the choice of sites decides the answer.
Officers check that the comparison is fair. We set out every selection choice, so the rates can be agreed rather than argued about.
- Land use and size, matched as closely as the data allows.
- Location type, such as town centre, edge of town or suburban, and local population and car ownership.
- Survey days and dates, excluding weekends and holidays where they would distort the result.
- Whether to use vehicle or multi-modal rates, so walking, cycling and bus trips are counted too.
Last reviewed October 2026 by Ripple Development Planning. Policy and guidance change; for advice on a specific site, send us the details.
From our insights.
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