Wednesday, October 01, 2008
Another tragedy on the tracks
What are we to make of the tragic head-on collision between a Metrolink commuter rail service and a UP freight train at Chatsworth in California's San Fernando Valley on September 12, which killed 25 people and injured 135 in the worst US passenger train accident for more than 15 years?
As is all too common, the simple cause appears to be that Metrolink train 111, outbound from Los Angeles Union Station on the Ventura County line, passed a signal at danger. It forced the blades of a locked turnout to enter the occupied single line instead of waiting at Chatsworth, where the two trains regularly passed each day, accelerating to around 65 km/h before meeting the double-headed freight train on a blind curve.
Such was the force of the collision that the Metrolink loco was driven three-quarters of the way back into the leading bi-level car, causing most of the fatalities and serious injuries. The entwined vehicles toppled over, but the other two coaches remained upright.
After testing signals, brakes and other equipment, National Transportation Safety Board investigators determined that the signal had been working correctly. NTSB calculated that the trains would come into sight of each other just 4 sec before the impact; the UP crew braked, but Metrolink driver Robert Sanchez, who was among the dead, did not.
Federal regulations require drivers who are alone in the cab to report every signal aspect by radio to their conductor, but NTSB member Kitty Higgins said the last two signal calls from train 111 were missing from the data, video and audio recordings recovered from the shattered loco. It was subsequently confirmed that Sanchez had been sending a text message on his mobile phone shortly before the collision.
Southern California Regional Rail Authority had already ordered a fleet of new coaches with Crash Energy Management following the 2005 Glendale collision, which led to questions over the safety of push-pull operation (RG 8.06 p440). However, the severity of the Chatsworth crash suggests that CEM might not have had much effect.
With much more intensive passenger services, European and Japanese operators have focused heavily on preventing collisions through the use of automatic train protection or similar technology to prevent trains passing signals at danger. Questions are being asked in California why Metrolink has not adopted Positive Train Control, although it is not clear whether this is yet sufficiently developed or reliable for widespread installation. According to an SCRRA spokesman, the sprawling five-county commuter network is too complex, and much of it is shared with heavy freight trains operated by UP and BNSF.
Nevertheless, California's US senators Barbara Boxer and Dianne Feinstein introduced draft legislation to Congress on September 16 that would require the installation of PTC on all mixed freight and passenger routes, with planning to be completed a year after the bill becomes law. Lines designated as 'high risk' by the Department of Transportation would have to be equipped by the end of 2012, and all other major routes by December 31 2014.
Several variants of PTC are under development, and widespread installation of a compatible system across the USA is estimated to cost up to US$2·3bn. But as the 1999 head-on collision at Ladbroke Grove in London showed, technology such as ATP is rendered useless if not all the trains operating on a line have been equipped.
Whilst every accident is a tragedy, it provides valuable opportunities to learn. Eurotunnel staff and fire crews dealing with the September 11 fire in the Channel Tunnel (p779) were able to draw on the experience of a similar fire in 1996, evacuating everyone from the train within 8 min. And the spectre of the horrific derailment at Eschede in 1998, caused by a broken wheel, led Germany's Federal Railway Office to intervene decisively when an ICE3 axle broke under a slow-moving train at Köln in July. Fortunately neither of these high-profile incidents resulted in any fatalities.
The railway industry enjoys a deserved reputation for safety, which compares well with the estimated 1·2 million deaths on the world's roads every year, causing a knock-on loss of economic productivity valued at US$100bn or more. This reputation has been hard earned over almost 200 years, as operators, authorities and regulators have sought to learn from successive incidents with different causes. Safety management regimes are improving all the time, yet accidents still happen. When one does, it remains as important today as ever before to challenge established practices, and consider whether technical advances offer opportunities to enhance safety at an acceptable cost.
