Glossary
Conveyal uses a special or specific meaning for several terms. While we hope that their meaning is usually clear enough from the context, this glossary is provided for reference.
Baseline network#
The baseline network is the transport network without any associated modifications. It is a useful point of comparison during analysis and a starting point for most modifications.
GTFS / GTFS feed#
General Transit Feed Specification, a format for transit network and schedule data. Most transit agencies produce GTFS feeds to power customer-facing trip planning applications, but they are also useful for analysis.
Isochrone#
An isochrone is a boundary around a given origin point defined such that travel from the origin to any point on the boundary takes an equal amount of time. Conveyal Analysis calculates travel time over a departure window, so the travel time used is actually a selected percentile in a distribution of travel times.
Modification#
A modification is an alteration of some kind made to scheduled transit services. e.g. the removal of a line, a rerouting, a new service etc. These must be activated in scenarios to be used in analysis.
Network bundle#
A network bundle consists of an OpenStreetMap file and one or more General Transit Feed Specification (GTFS) feeds associated with your region. A region can have multiple bundles, and a bundle can include a single agency's GTFS or feeds from several adjacent or overlapping agencies.
Opportunity dataset#
An opportunity dataset is a spatial dataset with one or more numeric fields representing a count of opportunities (destinations) at particular locations in your region. See uploading opportunities.
Project#
A project is means of associating scenarios and modifications with a particular network bundle. A project is associated with only one bundle, which cannot be changed after the project is created.
Region#
The region is the rectangular area used for accessibility analysis. It should geographically contain any scheduled transit services and network modifications.
Routing engine#
Conveyal R5 is the core computational software behind Conveyal Analysis. It performs one-to-many searches on multimodal (transit/bike/walk/car) transport networks.
Segment#
A portion of a trip pattern consisting of a transit vehicle traveling between two consecutive stops.
Scenario#
A scenario is a set of modifications packaged together. For example you might create a scenario, called "proposed service cuts" in which several modifications reduce service separately on lines A, B and C.
Transport network#
A routable network with street and transit layers, built from a network bundle by a specific version of R5. The street layer is based on OSM in the network bundle, and the transit layer is based on GTFS feeds in the network bundle.
Trip#
A single vehicle trip, representing a single vehicle visiting the stops on a particular trip pattern at a particular set of times.
Trip pattern#
A trip pattern is a sequence of stops visited by a transit vehicle. A trip pattern can have many trips, and a route consists of a one or more trip patterns. A basic two-way route might consist of two trip patterns - e.g. one for inbound service, one outbound. Each might make stops on different sides of the street and/or in a different order.