Economic growth and expanded global trade have led to substantial increases in goods movement over the past few decades. The growth in freight transportation demand, along with growing passenger-side demand, has caused congestion in many parts of the transportation system, making freight movements slower and less reliable. Because the condition and performance of freight infrastructure play a considerable role in the efficiency of the freight system, federal support of freight infrastructure investment is likely to be of significant congressional concern in the reauthorization of the surface transportation program. The program is currently authorized by the Moving Ahead for Progress in the 21st Century Act (MAP-21; P.L. 112-141 ) as extended to May 31, 2015, in the Highway and Transportation Funding Act of 2014 ( P.L. 113-159 ). There is significant disagreement about the best way to accomplish improvements in freight system infrastructure. Among the most important areas of disagreement are how to raise new funds for investment, the magnitude of the amounts required, how to set priorities, and the role of the federal government in the planning process. To some extent, these disagreements emerge from the diversity and complexity of the freight system itself, including its modal organization (truck, rail, water, air, and pipeline), the different levels of public and private ownership and involvement by mode, and competition among different regions of the country. The reauthorization of MAP-21 predominantly concerns highway funding. Consequently, the focus of this report is on truck freight and that portion of the rail industry that transports truck trailers and containers (intermodal freight). This report does not deal with operational issues that also may be of interest during reauthorization, such as hours of service and hazardous material transport safety. Moreover, this report does not discuss environmental issues associated with freight movements such as carbon emissions and climate change, air pollution emissions, and noise. The freight transportation system is a complex network of different types of transportation, known as modes, that carries everything from coal to small packages. It handles domestic shipments of a few miles as well as international shipments of thousands of miles. Rail carries the largest share of domestic freight measured in ton-miles, but only a small proportion by value ( Table 1 ), reflecting the fact that major rail cargos such as coal and grain have low ratios of value to weight. Trucks carry far more freight by value but less by ton-miles, as the average truck shipment travels a much shorter distance than the average rail shipment. Air transportation is a relatively minor mode for domestic shipments because it is expensive to ship goods by air. The proportions for international shipments to and from the United States are quite different than those for domestic shipments, with about three-quarters of goods, measured by weight, arriving or departing by ship. Measured by value, nearly one-fourth of U.S. international freight moves by air. Trucks run over a four-million-mile system of highways and streets. Of this, approximately 209,000 miles has been designated by the Federal Highway Administration (FHWA) as the "National Truck Network," a network of highways able to accommodate large trucks. This network includes the Interstate Highway System, which extends approximately 47,000 miles, plus principal arterial highways designated by the states. Trucks account for about 9% of vehicle miles traveled on the entire U.S. road system, but 15% of vehicle miles on Interstates and 24% on rural Interstates. The railroad sector is dominated by seven large railroads, or Class I carriers, that generally focus on long-distance moves. The Class I railroads are complemented by more than 500 short line and regional railroads (Class II and III) that tend to haul freight shorter distances, provide connections between the Class I networks, or connect the Class I network and ports. For the most part, railroad infrastructure, including track and associated structures and the land they occupy, is owned by the carriers themselves. The U.S. railroad network consists of approximately 140,000 miles of railroad, of which approximately 94,000 miles could be considered transcontinental or mainline railroad and 46,000 miles could be considered regional or local railroad. In some places, freight trains share space with intercity and commuter passenger trains. Although trucks and railroads often compete for shippers' business, they also may work together to complete freight movements. This is especially true in the case of long-distance movements. Railroads have established large intermodal yards designed for easy transfer of containers between trucks and trains at locations such as Edgerton, KS (BNSF) and North Baltimore, OH (CSX). In the face of high operating costs and a lack of drivers willing to undertake week-long trips, many truck lines now pick up freight from a shipper's premises, carry it to an intermodal terminal for transfer to a train, and then collect it at another intermodal terminal for delivery to its final destination. International shipments of containerized goods often move by rail between ports and inland terminals, with a truck connection to and from the rail terminal. This is why, as indicated in Table 1 , freight shipments moved by a combination of truck and rail tend to travel greater distances than goods moved by either mode singularly. Over the last decade, intermodal traffic has increased by nearly 30% (measured by the number of containers and truck trailers moved by railroads), making it the fastest- growing freight segment. While international trade growth traditionally has been the driver of intermodal growth, in recent years the number of domestic intermodal shipments has risen to nearly match the number of international shipments to and from the United States. Tonnage carried by trucks as a single mode has increased 14% over the last decade while rail tonnage carried as a single mode has increased by 7%. By 2040, U.S. DOT is forecasting that truck tonnage will increase by 43%, rail tonnage by 37%, and multimodal tonnage (of which intermodal is a subset) by 125%. Since 2011, the volume of coal carried by railroads, their most important revenue source, has declined significantly, while crude oil and drilling sand have suddenly become significant commodities for rail. The expansion of the Panama Canal, expected to be completed in early 2016, will allow the passage of container ships almost three times the current maximum capacity. The project may draw more Asian cargo through East or Gulf Coast ports at the expense of West Coast ports, but this is uncertain. Similarly, the enlarged canal could lead more grain grown in the Mississippi Valley to be shipped to Gulf Coast ports by barge for export to Asia rather than being shipped to West Coast ports by rail. The development of trade patterns will depend in part on the Canal's tolls and U.S. railroad rates. The arrival of larger container ships at Gulf Coast and East Coast ports could also exacerbate a persistent problem with moving trucks through port terminal gates efficiently. Growth in freight and passenger transportation demand has brought an increase in truck and rail congestion. This congestion is particularly pronounced in major urban areas that contain important freight hubs such as ports, airports, border crossings, and rail yards. As identified by the U.S. Department of Transportation (DOT), the 25 most congested segments for trucks are generally urban Interstate highway interchanges (see Appendix ). Six of the 25 most congested segments are in Houston and three are in Chicago. A trucking industry study estimates that 89% of the total costs of congestion for trucks are concentrated on 12% of Interstate highway mileage. Figure 1 depicts congestion on the highway system in the Southeast in 2011 during peak periods and how performance may deteriorate by 2040 without new capacity or operational improvements. Freight rail congestion has been episodic over the last couple of decades and has been caused by poor weather, demand surges, and railroad mergers. Currently, a boom in movements of crude oil from North Dakota, combined with a bumper harvest in 2014 and a residual backlog of shipments stemming from the severe winter of 2013-2014, is causing delays in rail service in the Upper Midwest. The railroad loading most of North Dakota's rail freight said it would spend $265 million in the state in 2014 to add parallel track segments. Both Class I railroads serving the state have blamed railroad congestion in Chicago, the crossroads of the North American rail system, as an underlying cause of current service issues (see text box). Local bottlenecks can take months if not years to resolve and may have effects across the entire rail network. Significant increases in train traffic on some lines have prompted upgrades to warning devices at grade crossings or interest in grade separation projects. Railroads seek changes to the environmental permitting process to expedite expansion projects. At land border crossings and seaports, congestion is less a matter of infrastructure constraints than staffing flexibility at customs booths and terminal gates. Truckers would like to see Customs and Border Protection better adjust staffing to accommodate daily peak crossing times at land border points of entry. Port terminal operators seek flexibility from longshoremen to extend truck gate hours to nights and weekends without charging premium rates. Long lines of trucks at some port terminals are also due to the bunching of port calls by steamship operators and their deployment of larger container ships. The prevalence of independent truckers, typically paid by the trip to the port, frustrates coordinated information processing and the truckers' ability to influence the situation. "U.S. port efficiency is among the lowest of world trading partners," according to one U.S. railroad. West Coast port inefficiencies are of particular concern for two of the nation's most valuable commodities exported in containers to Asia—chilled beef and pork. If more Asia-bound ships call at alternative ports in Canada, Mexico, or on the U.S. Atlantic Coast and reduce calls at U.S. Pacific Coast ports, chilled meat exports cannot easily be diverted to these ports because of their time sensitivity. There is no federal freight transportation program per se .