Many journeys made within the U.S. are intermodal in nature. For example, traveling from New York to central DC, you may use the subway and air train system to get to JFK to fly to Washington; then use Washington's Metro trains to get to the central area. Alternatively, ypu may take the subway to Penn Station in central Manhattan, Amtrak to Union Station, Washington, and a Metro train to the station nearest your destination. However, while these are intermodal journeys, they are not being made on one intermodal transport system.
A truly intermodal system is one that is specifically designed with interchange points where people can switch from one form of transport to another with ease and with ticketing; this means people do not have to pay separately for each part of the journey. Some systems give one ticket a time validity within the system. For example, the journey must be completed within 90 minutes but can be made on a variety of different types of transport. Other systems encourage the purchase of passes which are valid for different time spans such as one week or one year. Most systems encourage the purchase of passes by regular users by making each journey much cheaper if paid for in advance.
Dallas Area Rapid Transit (dart.org/default.asp) is a good example of an intermodal transportation system. A variety of passes are available --- one day, one week, one month and one year. Once purchased, these passes provide users with access to buses, light rail and commuter rail services. The level of access depends on whether the pass is "local," "system" or "regional." As of March 2011 an annual regional pass cost $1,200. This provides 12 month's travel on all of Dallas Area Rapid Transit's buses and trains, all Trinity Railway Express services, public transportation in Fort Worth, the DART "on-call" and "flex" service and the DCTA Commuter Express.
Dallas's Union Station is a good example of an intermodal transportation hub where passengers can easily change from one form of transport to another. It is a key station on the DART light rail network as it is served by both the red and blue lines. Passengers can make cross platform interchanges between these lines, and between the light rail system and Trinity Railway Express services to Forth Worth and Dallas/Fort Worth International Airport. Interchange with DART bus services takes place right outside the station.
