Public transit service, such as buses and subways, provides an important means of transportation in dense urban areas. The ArcGIS Network Analyst extension allows you to model schedule-based public transit service using a special data model and network evaluator in a multimodal network dataset. With a network dataset configured with public transit data, you can answer questions such as the following:
- What area of town can I reach within 30 minutes by walking and taking transit?
- What is the optimal location for a new clinic in Manhattan?
The primary purpose of network analysis using public transit data is analysis, not journey planning. Consequently, some features that would be valuable for passenger-facing applications are not currently available, such as transit-specific directions and real-time transit data.
See Create and use a network dataset with public transit data for more information.
Public Transit evaluator
The ArcGIS Network Analyst extension solvers perform a graph search through the edges of the network dataset. For each edge encountered, an evaluator performs a calculation to determine the cost (such as travel time) to traverse the edge. The Public Transit evaluator is a special type of evaluator that calculates the travel time along a transit line edge using the public transit schedules. The evaluator considers the time of day and date when the edge was reached and queries the schedules stored in a set of tables to find the most efficient transit trip available at the time and date specified for the analysis.
The Public Transit evaluator should be used to calculate the travel time only along transit line edges. Other network edges, such as streets or sidewalks, should use a different type of evaluator to accurately calculate walk time. With a properly configured network dataset, you can model a traveler walking from their origin along the streets, entering the transit system at a stop or station, riding the transit service to another transit stop or station, and then walking along the streets from the stop to their destination.
Public transit data model
To use the Public Transit evaluator and model schedule-based public transit within a network dataset, your network must include a specific set of feature classes and tables with a particular schema that define the transit stops and lines as well as the dates and times when transit service is available. These tables and feature classes comprise the ArcGIS Network Analyst extension public transit data model. The Public Transit evaluator is only available for the LineVariantElements feature class of the public transit data model and is not an option for any other edge source.
You can create and populate the data model feature classes and tables manually, or you can generate them automatically from General Transit Feed Specification (GTFS) public transit data by running the GTFS To Network Dataset Transit Sources and Connect Network Dataset Transit Sources To Streets geoprocessing tools.
Considerations and limitations
Not all functionality in the ArcGIS Network Analyst extension is currently supported for network analysis using public transit data. Some special considerations and limitations are described below.
Directions
Public transit turn-by-turn directions are not currently supported. If your network dataset includes public transit data, you can configure directions for the network, but routes that traverse public transit lines will produce directions instructing the traveler to walk or drive along the transit line rather than take a particular bus line and exit at a particular stop.
Real-time public transit data
Network analysis with real-time public transit data is not currently supported. Only the scheduled public transit service can be used in a network dataset. The use of public transit data in the ArcGIS Network Analyst extension is intended primarily for analysis; it is not recommended for journey planning and passenger-facing applications.
Vehicle Routing Problem analysis and Route analysis with reordered stops
Vehicle Routing Problem (VRP) analysis and traveling salesman problem analysis (using the Route solver with the option to reorder stops) are not currently supported for network analysis using the Public Transit evaluator.
Traveler behavior
It is not currently possible to limit the number of transfers used by the traveler.
It is also not possible to limit the traveler's walking time or distance separately from the overall travel time. For example, you cannot create a 30-minute service area but limit the walking time to 5 minutes. The service area output will show the area reachable within 30 minutes of walking, riding transit, or a combination of the two.
You can model travelers with wheelchairs or bicycles using attribute parameters on the impedance attribute that uses the Public Transit evaluator. The supported parameters are listed in the Public Transit evaluator documentation.