Upgrading Automatic Train Control Systems

For well over 100 years, the “track circuit,” which is deployed in fixed block train control systems, has been the primary element of Signaling for automated transit systems including automatic people movers (APM). Fixed block train control offers a proven solution that ensures passenger safety while meeting the transit system’s performance, maintainability, and availability goals. Throughout the years, fixed block train control has made many advancements; most notably the incorporation of microprocessor based interlockings in lieu of relay logic. Despite this and other improvements, fixed block technology remains a very hardware-centric solution to modern train control. Because of which, recent decades have seen the rise of communication based train control (CBTC) throughout the industry where the passing of vital data via radio communication allows signaling suppliers to eliminate the need of underlying track circuits. As APM installations that are near or are exceeding the design life of their current fixed block systems, decisions must be made as to the upgrade: refurbish and maintain the existing track circuited system or replace with CBTC. This paper will explore the advantages and downfalls with each approach. Also included are the considerations that property owners must keep in mind when upgrading automatic train control systems.