Communications-Based Train Control (CBTC) technology is the most advanced train control system for urban railway infrastructures. It is very different from conventional relay based signaling systems and more complex than most cab signaling systems. CBTC functions are numerous, highly complex with customized details for each project. They cannot be tested for all possible conditions at all locations. Knowledge of the CTBC system and experience with train control commissioning are keys to performing enough tests to detect most issues but permit the start of revenue service as early as possible. The testing strategy proposed by the CBTC supplier is the result of years of experience with the goal of minimizing expensive field tests while demonstrating that the system will work properly in revenue service. Despite the numerous tests performed before revenue service, it is inevitable that operating challenges will be faced during the first months of CBTC system operation.
The recent Institute of Electrical and Electronics Engineers (IEEE) Std 1474.4-2011 Recommended Practice for Functional Testing of a Communications-Based Train Control System  provides a good description how and where CBTC functions should be tested. However, it does not describe the sequence of tests in the context of a project where CBTC is deployed on a transit property. This paper presents the sequence of field tests required to commission a CBTC system and provides insight based on experience with several CBTC projects in the last decade.