Positive Train Control in Transition

A jointly developed positive-train control (PTC) system, which is interoperable among competing suppliers' communications systems, is the first significant step toward larger deployment of the technology since the early 1980s. Developed by suppliers GE-Transportation, Safetran Systems Corp. and Union Switch & Signal, the system is known as Communications-Based Signaling (CBS). Using radio and signal-based communications, it provides continuous overspeed protection, governs the safe movement of trains through a territory and allows secure communications between different substations. Key elements of this new generation of PTC are given, including the technique of replacing physical blocks as determined by track circuits with virtual blocks. Testing is scheduled for a number of carriers, including Alaska Railroad Corp., which would be the first installation of a PTC in dark territory. Other plans for PTCs at grade crossings are being made, and train management is being proposed for markets outside North America.