Intermodal Transportation:

A Variety of Factors Influence Airport-Intercity Passenger Rail Connectivity

GAO-13-691: Published: Aug 2, 2013. Publicly Released: Aug 2, 2013.

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Gerald Dillingham, Ph.D.
(202) 512-2684


Office of Public Affairs
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What GAO Found

Most major U.S. airports have some degree of physical proximity to intercity passenger rail stations, though only 2 airports are currently collocated with intercity rail stations. Specifically, 42 of the nation's 60 large and medium hub airports are located within 10 miles of Amtrak stations; 21 of the 42 airports are within 5 miles of Amtrak stations. At the 2 collocated airports, passengers can access Amtrak either via an automated people mover (Newark Liberty International Airport) or by walking (Bob Hope Burbank Airport). At some airports, such as Baltimore/Washington International Thurgood Marshall Airport, passengers can take a direct shuttle between the airport and the nearby Amtrak station, while at other airports, connections to Amtrak can be made through other modes of transportation. Studies and data, while limited, suggest that relatively few passengers in the United States use intercity rail to travel to and from the airport or through more integrated travel such as code-sharing agreements, whereby airlines sell tickets for Amtrak's service. The only existing air-rail code-sharing agreement in the United States is at Newark Airport. Amtrak and states are considering projects to expand intercity rail connectivity with airports, including as part of the construction of high-speed rail in California.

Air-rail connectivity may provide a range of mobility, economic, and environmental benefits, though the financial costs of building these connections could be substantial. Specifically, based on discussions with industry stakeholders, input from surveyed experts, and a review of academic literature, GAO found a general consensus that air-rail connectivity can provide a range of mobility benefits for travelers, though less agreement existed on the importance and extent of economic and environmental benefits. However, achieving these benefits could require significant trade-offs, because the costs of expanding the existing intercity passenger rail network and constructing viable connections can be significant. Given these costs, based on GAO's work, there are currently limited locations where benefits are high enough to justify funding to improve air-rail connectivity.

Air-rail connectivity remains limited in the United States, according to experts, as a result of institutional and financial factors, among other things. In particular, the limited nature of the existing intercity passenger rail network, including the frequency of service and connectivity to other transportation modes, remains an obstacle to developing and using air-rail connections. Securing funding for air-rail projects also remains a barrier. While funds from some federal grant programs can be used to help facilitate air-rail connections, there is no single funding source for air-rail projects.

There are strategies to improve air-rail connectivity, but adopting them involves trade-offs. Experts generally focused on, among other things, leadership, funding, and infrastructure improvements, though the effectiveness of these strategies may depend on a project's local characteristics. There has been little emphasis on air-rail connectivity by either the Department of Transportation (DOT) or Amtrak. Furthermore, experts noted that some of the strategies could be particularly challenging or costly to implement, such as in locations where the rail network was developed decades before airports. For example, increasing intercity passenger rail's frequency could improve air-rail connectivity but could also be expensive.

Why GAO Did This Study

Increasing passenger travel has led to growing congestion in the nation's air transportation system, and projections suggest that this trend is likely to continue. The integration of air and intercity passenger rail service, which is provided in the United States by Amtrak, has been suggested by some transportation experts as a strategy to increase mobility and reduce congestion in the United States. The FAA Modernization and Reform Act of 2012 mandated that GAO review issues related to air-rail connectivity. This report discusses (1) the nature and scope of air-rail connectivity, (2) the benefits and costs of air-rail connectivity, (3) factors affecting the development and use of air-rail connectivity, and (4) potential strategies to improve air-rail connectivity.

GAO reviewed laws, strategic plans, and academic studies. GAO analyzed data to determine distances between Amtrak stations and large and medium hub airports and interviewed officials from DOT, and representatives from Amtrak, the airlines, and aviation and rail industry associations. GAO interviewed stakeholders at eight large and medium hub airports, which were selected based on geographic location and extent of connectivity with Amtrak. In addition, GAO surveyed experts from the aviation industry, rail industry, state and local governments, academia and the private sector about air-rail connectivity issues. The survey and results can be found at GAO-13-692SP.

GAO is not making recommendations in this report. DOT and Amtrak provided technical comments, which were incorporated as appropriate.

For more information, contact Gerald Dillingham at (202) 512-2684 or

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