SSL Detrainment System

Working with Percy Lane Products and Bombardier, DCA designed this lightweight portable ladder system for London Underground’s S-Stock trains. This emergency detrainment system provides safe and rapid emergency egress for thousands of passengers per hour in a tunnel environment in the unlikely event of a train failure.

The system consists of two elements which fold flat for compact storage within the driver’s cab. First, a backlashless cantilevered platform is deployed to clear the driving vehicle’s extended coupler. The step assembly engages with retention features at the end of this platform and, once deployed, is supported by two tension straps connected to brackets mounted above the cab front door.

All aspects of the safety critical detrainment system design were undertaken by DCA, including detailed fatigue simulation and Finite Element Analysis predictions of peak stresses and deflections. These analysis results were validated by full system load and accelerated life testing at MIRA to ensure robust operation over the device’s 40-year design life.

Human factors played an important role in the design of the escape system. Deployment within 1 minute by any driver, including 5th percentile females, has been made easy by the development of a novel tension strap insertion and retention detail and by maintaining a total mass of just 15kg for the ladder assembly.