A CBTC system increases overall system performance by allowing trains to run closer together. This is accomplished by enabling each train to control its movements within a track area envelope provided by the trackside CBTC equipment. The compromises required by a one-size-fits-all traditional signaling block design are eliminated by a CBTC-equipped train determining its own individual stopping requirements based on the actual train’s capabilities.
The first CBTC systems were opened in 2003 in San Francisco and Singapore. Since then, several dozen CBTC systems have been built worldwide. CBTC systems in North America include airport people mover systems, several light rail lines, the New York City Subway Canarsie Line, and SEPTA’s Green Line Tunnel.