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 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.