A preliminary review of Link light rail’s low-speed, non-injury derailment on Nov. 16 shows the accident occurred after the train operator failed to follow established protocols for requesting access to the main line of the system and proceeded through a stop signal before entering the main line. The train then derailed while attempting to reverse course off the main line.

The two-car train was empty and coming into service when the operator moved through a stop signal on the access tracks at the Link Operations and Maintenance facility connecting to the Link mainline. Once on the mainline, staff at the Link Control Center detected the train in an incorrect position, ordered the operator to stop, then instructed the operator to visually check the track switches for correct alignment and then reverse course back onto the access tracks.

The review shows the operator failed to check the switches before walking to the other end of the train and reversing back down the access tracks. While making the reverse move back down the access tracks, the switch position caused two sets of wheels on the second train car to derail and block the southbound mainline tracks.

Under current protocols, train operators are required to stop at a signal, press a button to electronically call for a route, and radio the Link Control Center before entering the mainline tracks with their route information and to verbally verify the status of the signal before entering the mainline tracks. The route information sets the access switches to direct trains to the appropriate tracks. Once the route and switch settings are made, the control center and trackside signals approve moving onto the mainline when safe and give the operator permission to proceed.

The Link light rail system incorporates numerous safety features. The system is designed to automatically apply brakes to any train on a section of the tracks when it detects another train within an unsafe distance. No service trains were on the same section of mainline tracks when the accident occurred.

Sound Transit will continue to analyze the accident and review the Link signal and control system for training and operational improvements. Sound Transit will submit a final report to the Washington State Department of Transportation.