Implementing optical speed measurement (OSMES) for communications based train control

New York City Transit is installing communications-based train control (CBTC) as part of its signal modernization program starting with the Canarsie Line. CBTC requires a higher accuracy of speed and distance measurement than conventional signal systems. An optical speed and position measurement system (OSMES) that is independent of the wheel-rail interface is being used on this project. An accelerated program to develop this system into a production device had to be undertaken as well as solving many application obstacles, including severe clearance and environmental restrictions. Implementing an unproven subsystem on an operating transit system with tight project budget and schedule constraints presents many challenges.