Definitions

This page defines common words used in Mobility.

Transport Zone

A transport zone is a spatial unit used by the model.

People live in transport zones. Activities and opportunities are counted by transport zone. Transport costs are computed between transport zones.

Local Administrative Unit

A local administrative unit is an official administrative area, such as a French commune.

Mobility can use local administrative units to build a study area before creating smaller transport zones.

Synthetic Population

A synthetic population is a sample of people that represents the population of the study area.

It is a model input used to simulate daily mobility with represented people.

Activity

An activity is a reason to be somewhere during the day.

Common activities are:

  • home,

  • work,

  • study,

  • shopping,

  • leisure,

  • other.

Opportunity

An opportunity is something that can attract an activity to a zone.

Examples:

  • jobs for work,

  • schools for study,

  • shops for shopping,

  • leisure facilities for leisure.

In PopulationGroupDayTrips, raw opportunities are converted into activity-time capacity. An opportunity table helps distribute the amount of activity time that can be assigned to destination zones.

Mode

A mode is a transport option used to make a trip.

Common modes are:

  • walk,

  • bicycle,

  • car,

  • public transport,

  • carpool.

Generalized Cost

Generalized cost combines several costs of travel into one value.

It can include:

  • travel time,

  • distance cost,

  • a fixed cost for using a mode,

  • waiting or transfer penalties.

Mobility uses generalized cost to compare destination and mode choices.

For path-based modes, Mobility combines a fixed term, a distance term, and a time term. Distance is in kilometres and time is in hours. The resulting cost unit depends on the parameters chosen by the modeller.

Scenario

A scenario is a modelling assumption that can change between runs.

For example, a scenario can add a public transport line, change a speed, or add a cost to car travel.

Reference Scenario

A reference scenario is the situation used for comparison.

It can be the current mobility system, or a baseline agreed by the study team for a forecast year.

Iteration

An iteration is one step of the PopulationGroupDayTrips model loop.

Several iterations let the model update choices, costs, and opportunity saturation.

Replication

A replication is another run of the same setup with another random seed.

Replications help estimate how much results depend on sampling and random choices inside the model.

Survey Codes

French survey codes can appear in model inputs and outputs. They are listed on the survey codes reference page.