Intermodal Transportation: Challenges to and Potential Strategies for Developing Improved Intermodal Capabilities
Published: 2006-06-15T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: Mobility--that is, the movement of passengers and goods through the transportation system--is critical to the nation's economic vitality and the quality of life of its citizens. However, increasing passenger travel and freight movement has led to growing congestion in the nation's transportation system, and projections suggest that this trend is likely to continue. Increased congestion can have a number of negative economic and social effects, including wasting travelers' time and money, impeding efficient movement of freight, and degrading air quality. U.S. transportation policy has generally addressed these negative economic and social effects from the standpoint of individual transportation modes and local government involvement. However, there has been an increased focus on the development of intermodal transportation. Intermodal transportation refers to a system that connects the separate transportation modes--such as mass transit systems, roads, aviation, maritime, and railroads--and allows a passenger to complete a journey using more than one mode. This testimony is based on GAO's prior work on intermodal transportation, especially intermodal ground connections to airports, and addresses (1) the challenges associated with developing and using intermodal capabilities and (2) potential strategies that could help public decision makers improve intermodal capabilities.
section_title: What GAO Found
paragraphs: A number of financing, planning, and other challenges play significant roles in shaping transportation investment decisions and the development of intermodal capabilities. Significant challenges to the development of intermodal capabilities are the lack of specific national goals and funding programs. Federal funding is often tied to a single transportation mode; as a result it may be difficult to finance projects, such as intermodal projects, that do not have a source of dedicated funding. In addition, federally funded transportation projects, including intermodal projects, face a number of planning challenges. These challenges include limits on the uses of federal funds, ensuring that widespread public participation is reflected in decisions, physical and geographic land constraints, and the difficulty coordinating among multiple jurisdictions in transportation corridors. Finally, intermodal capabilities, while offering benefits to mobility, may need to develop a demand over time. Two general strategies developed from GAO's prior work would help public decision makers improve intermodal capabilities. Both strategies are based on a systematic framework that includes identifying national goals, defining the federal role, determining funding approaches, and evaluating performance. The first strategy would increase the flexibility of current federal transportation programs to encourage a more systemwide approach to transportation planning and development, but would leave project selection with state and local decision makers. The second strategy is a fundamental shift in federal transportation policy's focus on local decision making by increasing the role of the federal government in order to develop more integrated transportation networks. While the first strategy would most likely lead to a continued focus on locally determined and developed transportation projects, the second strategy could develop more integrated transportation networks, either nationwide or along particularly congested corridors. The second strategy could be costly, and high benefits, which may be difficult to achieve, would be needed to justify this investment.

section_title: Letter
paragraphs: Mobility—that is, the movement of passengers and goods through the  transportation system—is critical to the nation’s economic vitality and the  quality of life of its citizens. Mobility provides people with access to goods,  services, recreation, and jobs; provides businesses with access to material,  markets, and people; and promotes the movement of personnel and  material to meet national defense needs. However, increasing passenger  and freight travel has led to growing congestion in the nation’s  transportation system, and projections of future passenger travel and  freight movement suggest that this trend is likely to continue. For  example, the number of airplane passengers using U.S. airports is  expected to grow from over 746 million in 2005 to almost 1 billion by 2015  and, since most travelers use cars, whether privately owned or taxis, to get  to the airport, local cities and communities will face increased congestion  on their airport access roads and highways. In addition, freight traffic on  roadways has increased fourfold over the last two decades, and both rail  and highway congestion are particularly severe in urban areas where ports  for international trade are located. For example, in the Los Angeles area,  freight traffic is projected to more than double along the two mainline  freight railroads from 2003 to 2025. Increased congestion can have a  number of negative economic and social effects, including wasting  travelers’ time and money, impeding efficient movement of freight, and  degrading air quality. These effects are especially problematic in areas and  transportation corridors that are already heavily congested. Such  congestion may be relieved by intermodal transportation options—that is  a system that connects the separate transportation modes and allows a  passenger or freight to complete a journey using more than one mode,  such as bus, air, rail, and waterways.
Our past work has shown that the development of intermodal capabilities  can provide a range of benefits. Those benefits include potentially reduced  travel times and costs for travelers and freight by providing alternative  transportation options and eliminating freight “chokepoints” or  bottlenecks at entrances to freight facilities, and reduced road congestion  with the potential for an associated reduction in vehicle emissions and  improved air quality. Intermodal transportation capabilities are typically  initiated by state and local transportation agencies, including some  combination of state departments of transportation, local transportation  planning bodies (i.e., metropolitan planning organizations), airports,  seaports, and local transit agencies. The federal government’s role is  primarily one of funding and oversight through separate transportation  programs within the Department of Transportation (DOT). My testimony  today is based on our prior work on intermodal transportation, and  addresses (1) the challenges associated with developing and using  intermodal capabilities and (2) potential strategies that could help public  decision makers improve intermodal capabilities. In particular, I will be  drawing a number of examples from our July 2005 report on ground  access and intermodal connections at airports. (See Related GAO  Products.)
Financing, planning, and other challenges play important roles in shaping  transportation investment decisions and the development and use of  intermodal capabilities. Significant challenges are the lack of specific  national goals and funding programs to develop intermodal capabilities.  Federal funding is often tied to a single transportation mode; as a result it  may be difficult to finance projects, such as intermodal projects, that do  not have a source of dedicated funding. This may also make it difficult to  use federal funds to finance the best transportation investment, regardless  of mode, to improve mobility. In addition, federal transportation projects,  including intermodal projects, face a number of planning challenges that  include limits on the uses of federal funds, ensuring that widespread  public participation is reflected in decisions, physical and geographic land  constraints, and the difficulty in coordinating among multiple jurisdictions  in transportation corridors. Finally, intermodal capabilities, while offering  benefits to mobility, may need to develop a demand over time. For  example, in the case of ground access to airports, most passengers may  prefer to use private vehicles to access airport over transit options.
Two general strategies could help public decision makers improve  intermodal options. Both of these strategies are based on a systematic  framework that includes identifying the federal interest in and national  goals for transportation, defining the federal role, determining funding  approaches, and evaluating performance. In the first strategy, Congress  would increase flexibility within current federal transportation programs  to encourage the development of intermodal capabilities and  transportation investments that offer the best mobility improvements by  shifting federal transportation funding, which is generally focused on  individual transportation modes, to a more systemwide approach across  all modes and types of travel. This strategy would include having the  federal government develop approaches to target funding on  transportation investments that better focus on outcomes related to  national goals and promote better coordination between jurisdictions. The  second strategy is a fundamental shift in federal transportation policy’s  long-time focus on state and local decisionmaking by increasing the role of  the federal government in planning and funding intermodal projects in  order to develop more integrated transportation networks, either  nationwide or along particularly congested corridors. To develop a  nationwide intermodal system, the federal government could take on a  role similar to its efforts to develop the interstate highway system. A more  active federal government role might also require additional federal  funding responsibilities. For example, if the federal government were to  take a more active role in developing airport intermodal capabilities that  included enhancing or expanding rail service or developing high-speed rail  corridors, it might also need to increase its funding role, and the role of  other beneficiaries of the service, due to its high cost.
subsections: section_title: Background
paragraphs: Historically, federal transportation policy has generally focused on  individual modes rather than intermodal connections between different  modes. Federal transportation funding programs are overseen by different  modal offices within DOT—the Federal Aviation Administration (FAA),  Federal Transit Administration (FTA), Federal Railroad Administration,  and Federal Highway Administration (FHWA). No specific federal funding  programs have been established that target intermodal projects for either  passengers or freight although a few federal programs offer flexibilities  that would allow these types of projects.
Intermodal transportation refers to a system that connects the separate  transportation modes—such as mass transit systems, roads, aviation,  maritime, and railroads—and allows a passenger or freight to complete a  journey using more than one mode. For example, an efficient intermodal  capability at an airport would provide a passenger with convenient,  seamless transfer between modes; the ability to connect to an extended  transportation network; and high frequency of service among the different  modes. As shown in figure 1, an intermodal connection at an airport might  involve a passenger arriving at the airport by private shuttle service, flying  to another airport, and then transferring to local rail service or a  nationwide system, such as Amtrak, to reach a final destination. Similar to  airline passengers, an intermodal freight transportation system relies on  ready transport of cargo between ships and other transportation modes,  particularly highway and rail.
The scope and nature of intermodal passenger connections is further  illustrated by ground access to airports. In 2005, we reported that most  major U.S. airports have direct intermodal ground connections to either  local transportation systems or nationwide bus or rail networks. Sixty- four of the 72 airports that we surveyed reported having direct  connections to one or more local transportation systems in their area,  such as local bus or rail service, with 26 airports reporting having both.  The most common type of public transportation system available to and  from the airport is local bus service. Sixty-four airports reported having a  direct connection to a local bus service. However, the level of bus service  varies depending on the airport. For example, Seattle-Tacoma  International Airport has five public bus routes that serve the surrounding  communities, while General Mitchell International Airport in Milwaukee  has only one route that serves the airport. Twenty-seven airports reported  having a direct connection to a local rail system, such as light rail,  commuter rail, or subway. (See fig. 2.)
While most major U.S. airports are located in metropolitan areas that have  stations for nationwide transportation systems, such as Greyhound or  Amtrak, 20 airports reported having direct connections to nationwide bus  service or nationwide passenger rail service. Twelve of the 20 airports  reported having direct connections to nationwide bus service, and 14  airports reported having a direct connection to Amtrak rail service. (See  fig. 3.) All 14 airports provide shuttle service to transport passengers to  Amtrak stations that serve the metropolitan area. One of the 14 airports— Newark’s Liberty International Airport—reported that passengers could  also access the Amtrak station by an automated people mover. In addition,  the accessibility of Amtrak to Newark airport has allowed Continental  Airlines to establish a code share agreement with Amtrak, whereby  passengers can purchase one ticket for a journey that includes travel by  both air and rail. This agreement has allowed Continental Airlines to  eliminate some short-haul flights from Newark.
While there is no single federal funding source for rail to airport projects,  we found that local governments, airports, and transit systems were able  to tap and package a variety of federal funds to pay for recent rail  connections to airports. These included direct appropriations, the New  Starts program for fixed guideway transit systems, two federal aid  highway categories—the Congestion Mitigation and Air Quality  Improvement Program and the Surface Transportation Program—and   passenger facility charges at airports. Appendix I describes these  programs.
section_title: Several Significant Challenges Affect the Development and Use of Intermodal Capabilities
paragraphs: According to transportation research, planning officials, and our prior  work, a number of financing, planning, and other challenges play  important roles in shaping transportation investment decisions and the  development of intermodal capabilities. Significant challenges to the  development of intermodal capabilities are the lack of specific national  goals and funding programs. Federal funding is often tied to a single  transportation mode; as a result it may be difficult to finance projects,  such as intermodal projects, that do not have a source of dedicated  funding. Federal legislation and federal planning guidance all emphasize  the goal of establishing a systemwide, intermodal approach to addressing  transportation needs. However, the reality of the federal funding  structure—which directs most surface transportation spending to  highways and transit and is more oriented to passengers than freight— plays an important role in shaping local transportation investment  choices. In addition to the focus on highways and transit over other  investment choices, we found limited instances in which investment  decisions involved direct trade-offs in choices between modes or users— such as railroad versus highway or passenger versus freight.
A significant challenge to developing certain intermodal connections is the  difficulty of securing funding within the mode-specific federal funding  structure. The cost of intermodal projects can vary widely, depending on  the complexity and scope of the project. In addition, measuring and  forecasting the benefits from individual projects can be hard to quantify,  and we found only anecdotal evidence of benefits for the 16 intermodal  projects we examined. The costs of rail projects are typically substantial  and can include costs to construct a station, as well as track and other  infrastructure to support the rail network. Table 1 provides examples of  the costs of intermodal projects at airports and funding sources. We found  that many intermodal projects at airports fit the funding criteria for one or  more federal programs focused on surface transportation or aviation. For  example, FTA’s New Starts program is a significant source of funding for  intermodal capabilities at airports that are part of a rail transit system.  However, the rigorous rating process and increasing demands for its  limited funds make the New Starts program time-intensive and  competitive in nature and has made it difficult for local transportation  agencies to secure this funding, according to local officials that we spoke  with. Federal funding programs, like the New Starts program, will  contribute only a portion of the total project costs, subject to local  matching funds, which can be derived from local agencies such as  metropolitan transportation authorities, transit agencies, and airport  authorities. However, local transportation officials said it can be difficult  to secure local funds for intermodal projects at airports because these  agencies could potentially have different funding priorities, making it  difficult to build the unified local support necessary to secure funding.
Additionally, intermodal capabilities at airports can be funded with  passenger facility fees, commonly referred to as PFCs. Local  transportation officials also described difficulties in securing the use of  PFCs. In particular, requirements that PFC funds be used for projects on  airport property, among other criteria, are seen as limiting their use for  intermodal projects. Moreover, airlines support these restrictions on the  use of PFC funds, believing that these funds are for airport development  and capacity improvements, and not ground-access projects. However,  even with this restriction, we reported in July 2005 that four airport  authorities were using PFC funds to develop or contribute to intermodal  projects at airports, as shown in table 2.
In addition to the limits on the use of federal funds, federal transportation  projects, including intermodal projects, face a number of planning  challenges including the following:    Decision makers must ensure that wide-ranging public participation is  reflected in their deliberations and that their choices take into account  numerous views. During the planning of an intermodal project, the lead  local agency’s responsibilities include soliciting public comment regarding  the most appropriate project to select for the area. This public  participation can introduce considerations such as quality of life and other  issues that are difficult to quantify in making transportation choices. It  also puts decision makers in the position of balancing different public  agendas about funding and values.
The physical constraints of an area may present a challenge to building  intermodal facilities. The development of intermodal capabilities at  airports provides an example of this challenge. On the one hand, our work  has found that densely populated urban areas offer few alternatives for  expansion or new project development. On the other hand, it is these same  densely populated urban areas where rail connections to airports are more  likely to generate benefits that will justify the costs, as these areas may  have high levels of congestion and larger numbers of people willing to use  public transportation to access airports as a result. For example, since the  proposed light rail line into the Minneapolis/St. Paul International Airport  crossed land owned by various federal agencies, the process to gain the  needed right-of-way was a multiagency effort that required significant  coordination, adding somewhat to the project planning time and costs.
Multijurisdictional transportation corridors present special challenges in  coordinating investment decisions. Getting the cooperation of and  coordination between these different officials can make the planning and  implementation of multistate and multiregional projects difficult. For  example, during the planning of the Seattle light rail, Sound Transit  officials noted that the alignment from downtown Seattle to the Seattle- Tacoma International Airport ran through a number of surrounding cities  and required three local cities to approve permits for the construction of  the project.
The effective use of passenger rail as an intermodal option along heavily  traveled air and highway corridors also poses challenges due to limitations  of the existing nationwide rail network. For example, Amtrak’s passenger  rail network does not support air-rail service requirements because rail  lines do not go near some airports, passenger train schedules in some  parts of the country are not frequent enough to effectively link to airline  flight schedules, and transferring from air to rail poses inconveniences  that limit consumer demand. As we discussed previously, although 14  airports reported having a direct connection to Amtrak’s passenger rail  service, 1 reported that passengers could access the station by automated  people movers—others required boarding a shuttle. In addition, although  Amtrak track lines are adjacent to the Cleveland Hopkins International  Airport, Amtrak officials stated that Amtrak trains run only twice a day  along this line, which is not frequent enough to establish a code share  agreement with an airline.
Furthermore, transportation industry experts and European transportation  officials have pointed out that high-speed passenger rail, including  connections to congested airports, has provided an alternative for air  travel in short-haul markets in Europe. There has been a reduction of air  service between Paris, France, and Brussels, Belgium—a popular short  distance city pair for travelers—due, in part, to the high-speed train  service linking Paris Charles de Gaulle Airport and downtown Paris with  Brussels. In the United States, few efforts have been made to use rail  service to complement air service in this manner because, in part, the cost  of establishing service is not likely to justify its benefits given that some  distances are too great for rail to provide an attractive alternative  transportation mode.
Finally, intermodal capabilities, while offering benefits to mobility, may  need to develop a demand over time. For example, the development and  use of intermodal connections at airports can be limited by the inability of  the ground connections to meet the preferences of airline passengers,  therefore, the majority of passengers still use private vehicles to access  airports even when transit service is available. Passenger preferences can  include seamless transitions from one mode to another; a simplified  process to handle baggage; transit schedules that meet consumer  demands; and clear, easy-to-follow information on accessing  transportation options—including signs at airports and information at  hotels on accessing transit to airports. In addition, passengers, particularly  those traveling with children and large amounts of luggage, may not  consider using transit or rail systems to complete their travel plans due to  inconvenience.
section_title: Two General Strategies Could Help Address Intermodal Financing and Planning Challenges
paragraphs: Two general strategies could help public decision makers improve  intermodal options. These strategies are based on a systematic framework  that has the following three components:    Set national goals for the system. These goals, which would establish what  federal participation in the system is designed to accomplish, should be  specific and measurable.
Clearly define the federal role relative to the roles of state and local  transportation agencies and the private sector. The federal government is  one of many stakeholders involved in the development of intermodal  capabilities. This component is important to help ensure that the federal  role supplements and enhances the participation of other stakeholders and  appropriately balances public investment when the benefits flow in part to  the private sector.
Determine which funding approaches—such as alternatives to investment  in new infrastructure and those approaches that reward projects that  advance national/federal goals—will maximize the impact of any federal  investment. This component can help expand the ability to leverage  funding resources and promote shared responsibilities. Given the current  budgetary environment, and the long-range fiscal challenges confronting the country, substantial increases in funding for transportation projects  will require a high level of justification.
In addition, either strategy would be enhanced by a process for evaluating  performance periodically to determine if the anticipated benefits from  federally-funded projects are accruing as expected.
In the first strategy, Congress could encourage the development of  intermodal capabilities by increasing the flexibility with current federal  transportation programs, which are largely focused on individual  transportation modes, to a more systemwide approach across all modes  and types of travel. To promote intermodal development, the federal  government could consider several alternatives for transportation  planning and funding that might better focus on these outcomes and  promote better coordination between jurisdictions. These alternatives  include the following:  Increasing the flexibility of federal transportation funding programs to  help break down the current funding stovepipes.
Applying different federal matching criteria for different types of  expenditures in order to provide a higher level of federal matching for  projects that reflect federal priorities.
Establishing performance-oriented funding or a reward-based system that  would favor those entities that address the national interest and meet  established intermodal goals.
Expanding support for alternative financing mechanisms—such as  providing credit assistance to state and local governments for capital  projects and using tax policy to provide incentives to the private sector for  investing in intermodal capabilities—to access new sources of capital and  stimulate additional investment in intermodal capabilities.
Aligning incentives for planning agencies to adopt best practices and to  achieve expectations.
While this strategy would involve changes in federal transportation policy,  it would most likely not involve a major shift in the federal role, which  would continue to be focused on funding and oversight of locally  determined and developed transportation projects. However, since this  strategy would include the goal of establishing a more systemwide  approach to transportation planning, the federal government would need  to determine the scope of its involvement in encouraging such an  approach.
The second strategy is a fundamental shift in federal transportation  policy’s long-time encouragement of state and local decision making by  increasing the role of the federal government in planning and funding  intermodal projects in order to develop more integrated intermodal  networks, either nationwide or along particularly congested corridors.  This strategy could be similar to the strategy the federal government used  in the 1950s to develop the interstate highway system. Under this strategy,  Congress could establish national goals for the development of intermodal  capacities that could include not only the development of facilities and  connections, but also the development of a supporting transportation  network to improve the ability of either passengers or freight companies  to reach their final destination. The role of the federal government would  change, with the federal government taking a more active role in setting  priorities and planning of intermodal connections between the individual  transportation modes. Similar to the development of the interstate  highway system, the federal government’s role could include providing  project specific oversight, laying out routes, overseeing construction, and  ensuring that the system is adequately maintained.
For the federal government to take a more active role in developing  intermodal capabilities, it might also need to take on additional funding  responsibilities. An example would be if a federal policy were established  to develop a transportation system that promoted connections between  airports and high-speed rail networks, as in Europe. To accomplish  improved air-rail connections, the federal government would have to  increase its funding role due to the high costs of enhancing or expanding  rail service or developing high-speed rail corridors or tap others that  would benefit from such service, including the region, its airport, and  businesses associated with the airport as possible funding sources. The  full costs of this policy would be dependent on how integrated and  expansive such an intermodal network would be and whether it would  include additional high-speed rail or be focused on conventional passenger  rail service. We have shown in the past that both of these choices are  costly and increased federal involvement could require the  implementation of a dedicated funding source.
However, even if a revenue source is established, this new funding would  face many of the same revenue challenges that other transportation  systems, such as highways, are facing now as revenues sources are  eroded. Additionally, given the high costs of this strategy, benefits high  enough to justify investment in intermodal facilities would likely be  anticipated in a limited number of places.
section_title: Concluding Observations
paragraphs: Increasing passenger travel and freight movement have led to growing  congestion, and decision makers face the challenge of maintaining the  nation’s mobility while preventing congestion from overwhelming the  transportation system. Successfully addressing mobility needs in the face  of growing congestion requires both strategic and intermodal approaches.  However, the current system for planning and financing transportation is  not well-suited to advancing intermodal transportation projects— including both passenger and freight transportation—calling for  fundamental changes that use a broader, systemwide approach to  transportation investment decisions. A federal strategy of encouraging a  more systemwide approach to transportation planning, including  alternative funding mechanisms, could encourage transportation officials  to consider the development of additional intermodal connections in the  context of other transportation investment decisions. At the same time, it  is clear that more quantitative evaluations of the costs and benefits of  intermodal capabilities could help to better inform state and local, as well  as federal decision makers, as they attempt to determine which projects to  develop with their limited resources.
Mr. Chairman, and members of the Subcommittee, this concludes my  prepared statement. I would be pleased to answer any questions you or  other members of the Subcommittee might have.
section_title: GAO Contact and Staff Acknowledgments
paragraphs: For information on this testimony, please contact Katherine Siggerud at  (202) 512-2834 or siggerudk@gao.gov. Individuals making key  contributions to this testimony are Teresa Spisak and Tim Schindler.
section_title: Appendix I: Federal Programs That Can Fund Intermodal Projects at Airports
paragraphs: Selects worthy fixed guideway transit projects for  funding by congressional appropriations. Projects  can include heavy, light, and commuter rail and  certain bus transit projects (such as bus rapid  transit). To be eligible for funding, projects must,  among other things, be justified based on a  comprehensive review of mobility improvements,  environmental benefits, cost effectiveness, and  operating efficiencies, as well as being supported by  an acceptable degree of local financial commitment.  The program funding match is at most 80 percent  federal and 20 percent local. In fiscal year 2006, this  program was funded at $1.2 billion.
Funds transportation projects and programs in order  to reduce transportation-related emissions in  localities with poor air quality. To be eligible for  funding, projects must be transportation related, in  nonattainment or maintenance areas, and reduce  transportation-related emissions. The program  funding match is 80 percent federal and 20 percent  local. In fiscal year 2006, this program was funded at  $1.7 billion.
Provides funding to states and localities for projects  on any federal-aid highway—including transit capital  projects and local and nationwide bus terminals and  facilities. The program funding match is 80 percent  federal and 20 percent local. In fiscal year 2006, this  program was funded at $6.3 billion.
Provides federal credit assistance for surface  transportation projects. Project sponsors may  include public, private, state, or local entities.  Projects eligible for federal assistance through  existing surface transportation programs, including  passenger bus and rail facilities, are eligible for  credit assistance under this program. The amount of  federal credit assistance may not exceed 33 percent  of the reasonably anticipated project cost. In fiscal  year 2006, this program was funded at $130 million.
Provides grants to airports for planning and  development projects. The program is funded, in  part, by aviation user excise taxes, which are  deposited into the Airport and Airway Trust Fund. In  terms of promoting intermodal capabilities, these  funds may be used for access roads that are on  airport property, airport owned, and exclusively  serve airport traffic. The program funding match is  75 to 90 percent federal based on the number of  enplanements at the airport and the remainder is  from local sources. In fiscal year 2006, this program  was funded at $3.5 billion.
We found no example of its use for intermodal projects.
Authorizes commercial service airports to charge  passengers a boarding fee—commonly called a  passenger facility charge—of up to $4.50, after  obtaining FAA approval. The fees are used by the  airports to fund FAA-approved projects that enhance  safety, security, or capacity; reduce noise; or  increase air carrier competition. In calendar year  2005, $2.4 billion in fees were collected under this  program.
AirTrain automated people mover at New York’s John  F. Kennedy International Airport and Newark’s Liberty  International Airport Light rail extension and new station at Portland  International Airport  uating New Srt proposa, FTA plce greter priority on project tht hve  greter  locl mtching re. Competitive New Srt proposa often hve  40-50 percent locl mtch.  ir quality ndrd exit for certin common ir pollnt (known as criteri pollnt).  Geogrphic reas tht hve level of  criteri pollnt above thollowed y the ndrd re  clled nonttinment reas. Areas tht did not meet the ndrd for  criteri pollnt in the pasbut hve reched ttinment re known asintennce reas.
CAn enplnement i defined as assenger rding  flight. Enplnement inclde passenger  rding the firt flight of their trip, as well asassenger who rd fter connecting from nother  flight.
section_title: Related GAO Products
paragraphs: Freight Transportation: Short Sea Shipping Option Shows Importance of  Systematic Approach to Public Investment Decisions. GAO-05-768.  Washington, D.C.: July 29, 2005.
Intermodal Transportation: Potential Strategies Would Redefine Federal  Role in Developing Airport Intermodal Capabilities. GAO-05-727.  Washington, D.C.: July 26, 2005.
Highway and Transit Investments: Options for Improving Information  on Projects’ Benefits and Costs and Increasing Accountability for  Results. GAO-05-172. Washington, D.C.: January 24, 2005.
Surface Transportation: Many Factors Affect Investment Decisions.  GAO-04-744. Washington, D.C.: June 30, 2004.
Freight Transportation: Strategies Needed to Address Planning and  Financing Limitations. GAO-04-165. Washington, D.C.: December 19,  2003.
Marine Transportation: Federal Financing and a Framework for  Infrastructure Investments. GAO-02-1033. Washington, D.C.: September 9,  2002.
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