The U.S. railroad industry consists mostly of freight railroads but also serves passengers. Freight railroads are divided into classes that are based on revenue. Class I freight railroads earn the most revenue and generally provide long-haul freight service, while the smaller freight railroads— those in Classes II and III—earn less revenue and generally haul freight shorter distances. Amtrak provides intercity passenger rail service, while commuter railroads serve passengers traveling within large metropolitan areas. Freight railroads own most of the track in the United States, with a notable exception being the Northeast Corridor between Washington, D.C., and Boston, Massachusetts, which Amtrak predominantly owns. Railroads grant usage rights to one another, and passenger trains share track with freight railroads. While freight and passenger railroads share many characteristics, there are also key differences in their composition and scope (see table 1). The railroad industry also includes companies that produce railroad supplies, including locomotives, train cars, track, signal equipment, and related components, and national associations that work with and represent railroads. AAR, which primarily represents freight railroads (including all seven Class I freight railroads), as well as Amtrak and some other railroads, develops standards for the implementation of technology, manages the implementation of industrywide technological programs, and assesses the railroads’ needs for safety and technological development. It also works to develop new technologies at TTCI near Pueblo, Colorado, an FRA-owned railroad research facility operated by AAR through a contract. The American Short Line and Regional Railroad Association represents Class II and Class III freight railroads in legislative and regulatory matters. The American Public Transportation Association represents commuter railroads and develops standards for their use of technology. The U.S. railroad environment consists of train vehicles (rolling stock) and infrastructure, such as track, bridges and tunnels, switches and signals, and centralized offices with dispatchers (see fig. 1). Railroad accident rates have generally declined from 2000 to 2009. During that time, human factors and problems with track were the leading causes of rail accidents, according to our analysis of FRA data (see fig. 2). These problems can lead to train derailments or collisions, which can result in significant damage and loss of life. For example, the 2005 accident in Graniteville, South Carolina, was attributed to a switch being left in the wrong position, an example of human error, while the 2008 collision between freight and passenger trains in the Chatsworth neighborhood of Los Angeles, California, was the result of a commuter train going through a red signal it should have stopped at, which was likely caused by human error. Track-related causes of accidents include irregular track geometry, which occurs when rail is misaligned or too far apart; breaks in the rail or joints that connect rail segments; and damage to railroad bridges, among other causes. Such defects can lead to train derailments. Although the rate of accidents has decreased from 2000 through 2009, injuries and fatalities have fluctuated, with the largest spikes being tied to specific incidents. For example, injuries increased dramatically in 2002 due to one accident in North Dakota in which 1,441 people were injured from a derailment caused by track problems that resulted in the release of hazardous materials (see fig. 3). The number of fatalities per year from 2000 through 2009 ranged from a low of 4 in 2003 and 2009 to a high of 33 in 2005, the year of the accident in Graniteville, South Carolina, that killed 9 people. The second-highest year for fatalities was 2008; that year, there were 27 fatalities, including 25 fatalities from the accident in Los Angeles, California. In its role as federal regulator and overseer of railroad safety, FRA prescribes and enforces railroad safety regulations and conducts R&D in support of improved railroad safety and rail transportation policy. Within the agency, FRA’s Office of Railroad Safety promulgates and enforces railroad safety regulations, including requirements for track design and inspection; signal and train control systems; grade-crossing warning device systems; mechanical equipment, such as locomotives and freight cars; and railroad operating practices. For example, FRA’s regulations for track and equipment include detailed, prescriptive minimum requirements, such as wheel safety requirements and formulas that determine the maximum allowable speeds on curved track. In developing most of its regulations, FRA seeks input from the railroad industry and other organizations through its Railroad Safety Advisory Committee. FRA’s Office of Research and Development sponsors and conducts R&D of new rail safety technologies in support of FRA’s safety mission. This work contributes information used to support FRA’s development of regulations, standards, and best practices as well as encourages the development and use of new safety technologies. FRA’s R&D work is done collaboratively with industry and universities and is also supported by the Volpe Center, which is DOT’s transportation research center in Cambridge, Massachusetts. Although its role has traditionally been that of a regulatory agency, recently enacted laws have expanded FRA’s role in other areas. The Passenger Rail Investment and Improvement Act of 2008 authorized over $3.7 billion for three federal programs for high-speed rail, intercity passenger rail congestion, and capital grants, while the American Recovery and Reinvestment Act of 2009 appropriated $8 billion for these three programs. By creating a significant grant-making role for funding the development of high-speed passenger rail, these laws effectively transformed what was essentially a rail safety organization to one that is making multibillion-dollar investment choices while also carrying out its safety mission. Regarding rail safety technologies, the Rail Safety Improvement Act of 2008 directs FRA to oversee railroads’ implementation of PTC and other technologies. Specifically, the act requires passenger and major freight railroads to implement PTC by the end of 2015, with FRA playing a role as overseer of the industry’s implementation through rulemaking and review of railroads’ implementation plans. The act also directs FRA to require railroads to improve safety through the development of risk-reduction programs that include plans for implementing new rail safety technologies and to create a grant program to fund the deployment of rail safety technologies, authorized at $50 million per fiscal year from 2009 through 2013 (see table 2). PTC is a communication-based system designed to prevent some accidents caused by human factors, including train-to-train collisions and derailments caused by exceeding safe speeds. Such a system is also designed to prevent incursions into work zones and movement of trains through switches left in the wrong position. PTC achieves these capabilities via communication with various components, namely locomotive computers, devices along the track (known as wayside units), and dispatch systems in centralized office locations (see fig. 4). New data radios are being developed to enable wireless communication between locomotives and wayside units. Centralized offices and locomotives have access to a track database with information about track routes and other data, including speed restrictions, track configuration and topography, and the location of infrastructure such as switches and signals that indicate places where a train’s speed may need to be enforced by PTC. Using this information, locomotive computers can continuously calculate a train’s safe speed. If the train exceeds that speed, the PTC system should enforce braking as necessary. By preventing trains from entering a segment of track occupied by another train or from moving through an improperly aligned switch, PTC would prevent accidents such as those mentioned above that occurred in Los Angeles, California, and Graniteville, South Carolina. While the law does not require railroads to implement the same PTC system, it does require that railroads’ PTC systems be interoperable, which means that the components of different PTC systems must be able to communicate with one another in a manner to provide for the seamless movement of trains as they cross track owned by different railroads that may have implemented different PTC systems. Train control systems similar to PTC already exist in other countries. For example, a system to automatically stop trains if a train operator fails to stop a train at a stop signal has been widely used in Japan since the 1960s, although this system has been upgraded over time to provide advanced warning of the need to slow a train and automatically apply train brakes in such situations. A more advanced system to continuously calculate a train’s safe speed—similar to the capability that PTC is designed to achieve—is being implemented on the country’s high-speed passenger rail lines. In Europe, countries use various signal and train control systems, presenting technical and logistical challenges for trains that travel between countries. To establish interoperability among these systems, the European Union has embarked on an effort to implement the European Rail Traffic Management System, a common signaling and train control system, as well as a radio communications network, that would overlay countries’ existing signal and train control systems to establish interoperability among them. Like PTC, this system relies on a locomotive computer to calculate a train’s safe speed and enforce that speed on the basis of certain information, such as a train’s movement authority, the track speed limit, and the position of signals ahead of the train. In addition to the implementation plans outlined in the Rail Safety Improvement Act of 2008, FRA’s subsequent PTC regulations also require railroads to submit PTC development plans and PTC safety plans. These three plans are related, and FRA requires different information for each of them: PTC development plan: To get approval for the type of PTC system a railroad intends to install, the railroad must submit to FRA a plan describing the PTC system the railroad intends to implement and the railroad operations the PTC system will be used with.