Trip Distribution Models

Trip distribution models strive to predict the number of trips that will be made between a pair of zones for a particular trip purpose. These models try to mathematically describe the destination choice phase of the sequential demand analysis procedure. There are various models of trip distribution. However, most of the models incorporate the same basic factors which affect the number of trips between an origin zone and a destination zone. The models differ in their characterization of these factors and in the way these factors are assumed to affect the trip distribution.

The factors (for any given trip purpose) which affect the number of trips between two zones are:

• The number of trips produced by the origin zone.
• The degree to which the in situ attributes of the destination zone attract trip makers. The attributes which gain importance varies with the trip purpose. For example, if one is modeling the number of shopping trips attracted to a zone then the type of attributes of the zone which assume importance will be total shopping floor area, number of retail outlets, etc. On the other hand, if one is modeling the number of work trips attracted to a zone then the type of attributes of the zone which assume importance will be the number of offices, the type of offices, etc.
• The factors that inhibit travel between a pair of zones. These factors could be, travel time, travel distance, travel cost, etc.

Four different models are presented here. These are (i) Gravity model, (ii) Intervening opportunities model, (iii) Choice model, and (iv) Entropy Model.