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NTSB Because ATC does not control a train's speed in all circumstances, Amtrak installed the Advanced Civil Speed Enforcement System (ACSES), which FRA has said meets the conceptual requirements of PTC, on portions of the Northeast Corridor in 2000. (See figure 5.)



Figure 5. PTC (ACSES) was installed on the Northeast Corridor in 2000.

The ACSES system was designed to enforce speeds that were not enforced by ATC, such as some permanent speed restrictions on curves and bridges and maximum authorized speeds as prescribed in the operating timetable. The system was also designed to enforce a positive stop at interlocking signals and temporary speed restrictions via a data radio communication system.

In 2010, the FRA issued regulations for PTC systems in accordance with the Rail Safety Improvement Act of 2008, which required PTC to be implemented nationwide by December 31, 2015. (This deadline was later extended to December 2018.) ACSES was the first PTC system to be certified by the FRA. Amtrak had installed ACSES on all Amtrak-owned track on the Northeast Corridor required to be PTC-equipped by the end of 2015. PTC is now fully operational from Washington, DC, to Boston. Thus, all curves with a speed change such as 15