In 1922, the Interstate Commerce Commission (ICC), predecessor agency of the Federal Railroad Administration (FRA), issued the first order under the Transportation Act of 1920 to require 49 railroads to install either a train stop or train control system on at least one division over which passenger trains operated. Since that time, using technology to keep trains apart has been a strategic public policy goal. Currently, implementation of “positive train control systems” is one of the board’s Most Wanted List of transportation safety improvements.

As microprocessor technology entered the realm of railroad signaling and train control during the 1980s, the railroad industry, through the Association of American Railroads (AAR) and the Railway Association of Canada (RAC), developed detailed, tiered specifications for implementation of an advanced train control system (ATCS) that were based on the use of a digital radio communication network and microprocessor controls. As conceived, ATCS had ambitious safety and operational goals, including the replacement of existing wayside signal systems. During the same period, the BNSF Railway Company (BNSF) worked with Rockwell International to develop and demonstrate the Advanced Railroad Electronics System (ARES), which utilized data radio links and wayside equipment similar to ATCS, but foretold the future of the general rail system by relying on a global positioning system (GPS) for train location. Although both of these systems were considered to be technical successes, they were subsequently abandoned. However, ATCS radio technology was incorporated into newer traffic control systems to support pole line elimination, and much was learned from the ATCS and ARES development efforts.

In 1994, FRA delivered to Congress a report titled, Railroad Communications and Train Control that pronounced ATCS specifications to be sound and commented favorably on ARES. The report, required by the Congress, also introduced the term “positive train control” (PTC) for the first time and used it to refer to technology that could automatically intervene to prevent train collisions, control a train’s speed and ensure that trains operate within authorized limits. During the same year, the AAR and RAC abandoned their commitment to ATCS, but two freight railroads began the first of a series of new pilot projects designed to demonstrate PTC technology using GPS (augmented or not) to locate trains.

As the 1990s proceeded, the progress of high-speed rail development in the United States became a key element of the U.S. Department of Transportation’s (DOT) Next Generation High-Speed Rail Program. Digital radio communications technologies were seen as an alternative means for the railroads to enhance safety, and at the same time meet the requirements for high-speed rail implementation at a cost significantly lower than that of existing hardwired technologies.

In September 1997, FRA asked the newly formed Railroad Safety Advisory Committee (RSAC) to establish a PTC Working Group. One of the group’s first actions was to make clear that the term PTC, even though commonly associated with highly capable microprocessor and communication-based technologies used to prevent train accidents, should be reserved for a set of safety objectives, rather than a specific technology. The working group affirmed that the three core objectives of PTC systems are to prevent train collisions, to enforce speed restrictions and to provide protection for roadway workers. In 1999, the RSAC delivered to FRA’s administrator a report titled, Implementation of Positive Train Control Systems that attempted to describe a realistic blueprint for successful deployment of the technology. (The report was appended to a letter report to the Congress filed by the administrator in May 2000.) It identified specific actions that government and industry would both need to undertake if PTC was to be deployed successfully across the nation’s rail network.

Initial Steps Toward Deployment
Amtrak made the first use of PTC technologies. Based on advice regarding requirements from FRA’s Office of Safety, and ultimately supported by a 1998 order requiring its deployment, Amtrak rolled out the Advanced Civil Speed Enforcement System (ACSES) which, coupled with the existing cab signal and automatic train control systems, provides PTC capabilities supporting train speeds of up to 150 mph. Although ACSES uses transponders to determine train location, Amtrak decided to pursue the GPS-based approach for its Incremental Train Control System (ITCS), which is deployed on its Michigan line. This system has been employed in service under an FRA waiver granted in March 2000 and has supported 90-mph service since January 2002.

On the freight side, PTC remains a technology undergoing testing and demonstration, but the overall pace of its implementation is increasing rapidly. When the 1999 RSAC report was delivered, FRA was already working with CSX Transportation (CSXT) on its Communication-Based Train Management System (CBTM) and a number of other related freight railroad projects were underway (several of which were later terminated or significantly redirected). At that time it became clear to FRA that the Class I railroads were serious, but still striving to identify reliable and properly scaled technology.