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 Intermodal Passenger Connectivity Database (IPCD)
The Intermodal Passenger Connectivity Database (IPCD) is a nationwide data table of passenger transportation facilities and bike-share stations, with data on the availability of connections among the various scheduled public transportation modes at each facility. In addition to geographic data for each facility, the data elements describe the availability of intercity, commuter and transit rail; scheduled air service; intercity and transit bus; intercity and transit ferry services; and bike-share availability. Transit bus service locations are not specifically included in the database. However, the status of transit bus as a connecting mode is included for each facility in the database.


Intermodal connections, the links that allow passengers to switch from one mode to another to complete a trip, have been an important element of federal transportation policy since passage of the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). ISTEA marked a major change in federal transportation policy. Instead of considering the needs of each mode individually, ISTEA sought to encourage the development of intermodal connections, stating that "The National Intermodal Transportation System shall consist of all forms of transportation in a unified, interconnected manner." Since then, the U.S. Department of Transportation has encouraged the development of intermodal connectivity. Interconnecting the modes would give both shippers and travelers transportation alternatives that unconnected, parallel systems do not offer. Also, with interconnectivity, the system would function more efficiently because each mode would be relied on for the transportation that it could most effectively provide.

There is a general consensus that the U.S. passenger transportation system has become more intermodally linked since the passage of ISTEA, but the degree of that connectivity has never been measured. The Intermodal Passenger Connectivity Database (IPCD) was developed to provide a baseline connectivity measurement against which to measure future progress.

The most precise measurement of passenger transportation system connectivity would be to measure how many trips are actually made using multiple public transportation modes. While it might be possible to capture these data for some services, at the majority of connecting terminals passengers simply make a connection themselves from one mode to the other, and the existence of an intermodal trip is not recorded. Without actual intermodal travel data, the most reasonably measured proxy for determining the intermodal capacity of the system is to focus on how many terminals offer links between modes.

Since 2007 the Bureau of Transportation Statistics (BTS) of the United States (U.S.) Department of Transportation (DOT) has been collecting that data on an on-going basis.

The IPCD data covers the following types of passenger transportation terminals:
  • Scheduled airline service airports.
  • Intercity bus stations (includes stations served by regular scheduled intercity bus service such as Greyhound and Trailways, code sharing buses such as "Amtrak Thruway" feeder buses, supplemental buses that provide additional frequencies along rail routes, and airport bus services from locations that are outside of the airport Metropolitan Area.
  • Intercity and transit ferry terminals.
  • Light rail transit stations.
  • Heavy rail transit stations.
  • Passenger rail stations on the national rail network served by intercity rail and/or commuter rail services.
  • Bike-share stations.
   Data Sources
The IPCD utilizes data from several DOT databases and also from many public information and data sources. For the geographic coordinates of terminals that were not available, BTS used various mapping websites that contained satellite or aerial imaging. Facilities were located from the images and the latitude and longitude calculated.

To ensure that all locations with service were included in the IPCD, in addition to available databases BTS used the websites of rail, bus, air and ferry operators; local and regional transit agencies; state departments of transportation; and various sites that aggregate public transportation information. BTS also used printed public materials such as timetables, maps, and brochures issued by various public transportation providers, and facility databases provided by Greyhound, Amtrak, and the Alaska Railroad. In some cases, personal communication was used to clarify questions about the various terminal facilities.
   Data Collection
The IPCD data has been collected on an ongoing basis, rather than as of a specific date. Since the passenger transportation system changes on a daily basis, information concerning any specific facility may have changed since the data in a particular IPCD record was last collected. Updates to the IPCD data may lag behind the actual changes that have occurred, but the impact of those changes does not invalidate the overall picture that the data presents, nor make it invalid for giving a system snapshot for analyzing long-term progress toward increased connectivity. Users of the database should be aware that changes at specific terminals may have occurred since the data was last collected. Each record has a field entitled Date_Updated that tells the last date on which data for that particular record was changed.
   Accessing the Data
BTS provides access to the IPCD data either through use of the IPCD Query tool or through download of the entire base. The Query Tool allows users to create multi-variable cross-tabulations on mode, terminal type, state, metropolitan area and several other variables. Users with a need to customize and manipulate the data for various purposes may choose to download these files instead of using the interactive query tool.

A query tool user guide is available at the query tool site.