SAN FRANCISCO — In its continuing investigation of the collision between two San Francisco Municipal Transportation Agency (SFMTA) light rail trains on Saturday, injuring more than 40 people, NTSB Acting Chairman Mark V. Rosenker has announced the following factual information:
At about 2:50 p.m. PDT on Saturday, July 18, 2009, an L Line train struck the rear of a K Line train at the West Portal Station in San Francisco.
Data captured by recorders in the train control center indicated that the L Line train was switched from automatic to manual mode while stopped in the tunnel at the same time that the K Line train was occupying the track at the station. Approximately 24 seconds after the L Line train was switched to manual mode, it struck the stationary K line train.
The L Line train was traveling at between 20 and 23 miles per hour at the time of the collision.
Post-accident examinations have not revealed any problems with the braking system or any other mechanical element of the train. There was no indication that the emergency brake was activated.
An evaluation of the signal system did not reveal any anomalies or malfunctions with the performance or functionality of the system.
Rosenker said that the lead NTSB investigator interviewed the operators of both trains involved in the collision, as well as an employee monitoring operations and train activity at the train control center. The operator of the L train that struck the K train told the investigator that he “blacked out” as his train approached the platform.
The NTSB will be reviewing the medical history and records of the operator as well as any current medical conditions or treatments that he may have been under at the time of the accident.
While there is no indication at this point that the use of a mobile phone played any role in the collision, the mobile phone records of the operator of the striking train have been subpoenaed for review, which is a routine aspect of such accident investigations.
SFMTA provided the Safety Board with a video recording of the collision that was taken from a surveillance camera mounted at the West Portal station. A copy of the video was sent to the NTSB’s vehicle recorder laboratory in Washington where an initial examination of the recording was completed.
The NTSB has released control of the video recording back to SFMTA.
The on-scene phase of the investigation has been completed and both of the Los Angeles-based NTSB investigators have returned to Southern California.
The parties to the investigation are SFMTA, the California Public Utilities Commission, and the Federal Transit Administration.