Demand model
The Demand model is a component of the TMfS transport model.
The Demand model is the process which is used to create forecast trip levels. It takes into account forecast year schemes and policy changes to incrementally modify the base year demand.
The TMfS:07 Demand Model is an extension of the conventional 'four-stage' demand model, and incorporates the following stages/choices. (The traditional elements of a four-stage model are denoted in bold.)
- trip generation;
- trip frequency;
- mode choice;
- destination choice;
- park and ride station choice;
- high occupancy vehicle choice; and
- route choice (assignment).
The outputs from the demand model are:
- vehicle trip matrices;
- public transport passenger trip matrices; and
- park and ride station choice.
The demand model operates at time period level (AM Peak - 07:00-10:00, Inter Peak - 10:00-16:00 and PM Peak - 16:00-19:00), with the following purpose and household segmentation:
- Home-Based Work (HBW) – travelling ‘from home’ to work (and back again) – a typical commuting journey (this travel purpose does not take place in employer’s time);
- Home-Based Other (HBO) – travelling ‘from home’ to a non work-related location such as shopping or leisure (but excluding education);
- Home-Based Employer’s Business (HBEB) – travelling ‘from home’ to a destination during the employer’s time;
- Non-Home-Based Other (NHBO) – travel between two Non-Home-Based locations (eg from work to shops);
- Non-Home-Based Employer’s Business (NHBEB) – travelling during employer’s time, such as travelling from the place of work to a business meeting, visiting customers etc; and
- Home-Based Education (HBS) – travelling ‘from home’ to an education destination (eg school, college etc). These are not part of the main Demand Model, but are added in separately after the mode and destination choice phases.
These travel purposes are further segregated by four household types:
- C0 – zero car household;
- C1/1 – 1 car, 1 adult household;
- C1/2+ – 1 car, 2+ adult household; and
- C2+ – 2+ car household.
