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Trip generation

Land use is a primary driver in the overall travel demand of a transportation system. The distribution of homes, jobs, and services across urban space governs where trips originate and end.

The Trip Generation model calculates the number of trips produced and attracted to every part of the city based on production factors per zone feature for different urbanization degrees and population groups.

The model enables planners to interactively evaluate the impact of demographic and land-use changes, such as modifications to population, employment distribution, or housing density on travel demand in the city.

Controls

The model responds to the following controls:

  • Zone feature

    Add or remove zone features such as housing, jobs and amenities as defined in the demand_generation_factors collection.

  • Feature definition

    Define a new feature in the demand_generation_factors collection, such that it can be used by the zone features control.

Controls are defined in the controltype collection located in the main bin, the default set consists of:

ICON JSON NAME OBJECT_ID OBJECT_TYPE
zone-features [{"name":"FEATURE_TYPE","type":"text","label":"Feature type","default":"","validate":""},{"name":"FEATURE_VALUE","type":"text","label":"Feature value","default":"","validate":""}] Zone features 1 zone
global-control [[{"name":"FEATURE_TYPE","type":"text","label":"Feature type","default":"","validate":""},{"name":"FEATURE_TYPE_ID","type":"number","label":"Feature type id","default":"","validate":""},{"name":"MAX_ATTRACTION_FACTOR","type":"number","label":"Max attraction factor","default":"","validate":""},{"name":"MAX_FACTOR","type":"number","label":"Max factor","default":"","validate":""},{"name":"MAX_PRODUCTION_FACTOR","type":"number","label":"Max production factor","default":"","validate":""},{"name":"MIN_ATTRACTION_FACTOR","type":"number","label":"Min attraction factor","default":"","validate":""},{"name":"MIN_FACTOR","type":"number","label":"Min factor","default":"","validate":""},{"name":"MIN_PRODUCTION_FACTOR","type":"number","label":"Min production factor","default":"","validate":""},{"name":"OBJECT_ID","type":"number","label":"Object id","default":"","validate":""},{"name":"POPULATION_GROUP_ID","type":"number","label":"Population group id","default":"","validate":""},{"name":"PURPOSE_ID","type":"number","label":"Purpose id","default":"","validate":""},{"name":"UNIT","type":"text","label":"Unit","default":"","validate":""},{"name":"URBAN_LOCATION","type":"text","label":"Urban location","default":"","validate":""},{"name":"URBANIZATION_DEGREE","type":"text","label":"Urbanization degree","default":"","validate":""}]] Zone features 2 demand_generation_factors

Parameters

Parameters are defined in the parameters key/value sets and are scenario specific.

Parameter Description Default value
scenarioType Determines which factor from the demand_generation_factors collection is used, either Minimum 0, Average 1 or Maximum 2 1
purposes Determines which purposes to calculate. When left empty, all purposes from the demand_purposes collection are used. To use a subset of purposes, enter the OBJECT_ID from the demand_purposes collection as a list.

Data collections

Data collections from the base bin:

Collection Description Bin
demand_generation_factors Definition of the production and attraction factors per feature, purpose, population, urbanization degree and urban location. scenario
demand_attraction Resulting number of trips per population and purpose group attracted to each zone. scenario
demand_populations Definition of the population groups. scenario
demand_production Resulting number of trips per population and purpose group produced by each zone. scenario
demand_purposes Definition of travel purposes. scenario
traf_zones Definition of the zones in the scenario. scenario
zone_features The feature types (such as houses, job locations, amenities) per zone. scenario
Field Schema Description Subscription
FEATURE_TYPE string Description of the feature read
MAX_ATTRACTION_FACTOR double The maximum factor for calculating the trip attraction read
MAX_PRODUCTION_FACTOR double The maximum factor for calculating the trip production read
MIN_ATTRACTION_FACTOR double The minimum factor for calculating the trip attraction read
MIN_PRODUCTION_FACTOR double The minimum factor for calculating the trip production read
OBJECT_ID int32 Unique identifier for the record read
UNIT string Unit of measurement for the demand values in this record read
URBAN_LOCATION string Specification of the factor for the urban location, pointing to the OBJECT_ID in the traf_zones collection read
URBANIZATION_DEGREE string Specification of the factor for the urbanization degree, pointing to the OBJECT_ID in the traf_zones collection read

Difference between the MIN_ and MAX_ factors.

The scenarioType parameter determines if the MIN_, MAX_ or an average of the two is used for calculating the trip attraction and production.

Field Schema Description Subscription
ATTRACTION double The number of calculated trips attracted to the zone write
POPULATION_GROUP_ID int32 The population group of the trips, pointing to the OBJECT_ID in the demand_populations collection write
PURPOSE_ID int32 The purpose for the trips, pointing to the OBJECT_ID in the demand_purposes collection write
ZONE_ID int32 The zone to which the trips are attracted, pointing to the OBJECT_ID in the traf_zones collection write
Field Schema Description Subscription
LABEL string Description of the population group read
OBJECT_ID int32 Unique identifier for the population group read
Field Schema Description Subscription
POPULATION_GROUP_ID int32 The population group of the trips, pointing to the OBJECT_ID in the demand_populations collection write
PRODUCTION double The number of calculated trips produced by the zone write
PURPOSE_ID int32 The purpose for the trips, pointing to the OBJECT_ID in the demand_purposes write
ZONE_ID int32 The zone from which the trips are produced, pointing to the OBJECT_ID in the traf_zones collection write
Field Schema Description Subscription
NAME string Description of the purpose read
OBJECT_ID int32 Unique identifier for the purpose read
Field Schema Description Subscription
OBJECT_ID int32 Unique identifier for the zone read
URBAN_LOCATION_STRING string The urban location of the zone, such as rural or city center read
URBANIZATION_DEGREE string The urbanization degree of the zone, such as not urban or highly urban read
Field Schema Description Subscription
FEATURE_TYPE string Description of the feature, pointing to the OBJECT_ID in the demand_generation_factors collection read
FEATURE_VALUE double The value for that specific feature read
OBJECT_ID int32 Unique identifier of the zone feature read
ZONE_ID int32 The zone of the feature, pointing to the OBJECT_ID in the traf_zones collection read

Data requirements

The calculation model requires the following data:

Dataset Description Common source Importance
Production and attraction factors The number of trips produced and attracted by each zone feature such as houses, jobs and amenities. Conventional traffic model such as Visum, OmniTRANS or Emme. Required

Methodology

The trip generation model calculates, for every zone, how many trips are produced by and attracted to that zone, per population group and travel purpose. It does this by combining the zone_features with the production and attraction factors as defined per feature type.

Each feature type has a minimum and a maximum production and attraction factor. The scenarioType parameter determines which of these is used in the calculation.

For every zone \( i \), the model sums the contribution of each zone feature present in that zone, weighted by its selected production factor:

\[ P_i = \sum_{f \in F_i} v_{f,i} \, \alpha_f \]

Attraction is calculated analogously:

\[ A_i = \sum_{f \in F_i} v_{f,i} \, \beta_f \]

where:

  • \( P_i \) is the total production of zone \( i \)
  • \( A_i \) is the total attraction of zone \( i \)
  • \( F_i \) is the set of feature types present in zone \( i \)
  • \( v_{f,i} \) is the value (amount) of feature \( f \) in zone \( i \)
  • \( \alpha_f \) is the production factor for feature \( f \)
  • \( \beta_f \) is the attraction factor for feature \( f \)