Tuesday, September 03, 2013

Expect the unexpected

Written by  David Briginshaw, Editor-in-Chief, International Railway Journal
In an ideal world, human beings would never make mistakes and equipment and systems would never fail. Unfortunately we don’t live in utopia, as the spate of serious railway accidents during the last few weeks in France, Spain, and Canada reminds us all too vividly.

Learning the lessons from accidents has been one of the drivers of the steady improvement in railway safety, but one cannot help feeling that the terrible Renfe (Spanish National Railways) accident on July 26 at Santiago de Compostela, Spain, in which 79 people died and many more were injured when a train entered a curve well in excess of the 50 mph limit and derailed, has strong echoes from previous British accidents.

Although the full investigation into the accident is still under way, the Spanish government has already acknowledged that engineer error and the lack of working ETCS (European Train Control System) equipment were the main causes of the crash, while the use of a cell phone might have distracted the engineer and been a contributory factor.

As International Railway Journal Spanish correspondent Fernando Puente exclusively revealed, although both the Ourense-Santiago high speed line and the Talgo Class 730 train involved in the accident were fitted with ETCS, it was not operational on the train for this particular line. The reason why this was so will have to wait until the publication of the accident report, but clearly more effort should have been made to make the system fully functional both on the train and, more important, to install it on the section where the line speed reduces from 125 mph to just 50 mph to allow trains to negotiate the two sharp curves on the approach to Santiago. One of the main benefits of ETCS is its inbuilt ATP (automatic train protection) system is designed to prevent trains from exceeding track speed.

The final ETCS transponder, located about 2.5 miles from the curves, informs engineers on trains with functioning ETCS that the train is exiting the ETCS zone, so full supervision ends and operation is entirely manual, and the maximum speed is 125 mph. If ETCS had been functioning on the train, the engineer would have had to acknowledge the transition from ETCS to ASFA (Anuncio de Señales y Frenado Automático, or “Automatic Braking and Announcement of Signals,” the Automatic Warning System widely deployed on the Spanish rail network), otherwise the train would have braked. If this final transponder had been programmed for a maximum exit speed of, say, 60 mph, the accident would have been averted.

The ASFA system installed beyond this point was not designed to control train speed, but only prevent trains from passing signals at danger. Despite this, there were no wayside markers to warn drivers of the 50 mph speed restriction. Spain’s Development Minister, Ana Pastor, says that fixed signals indicating the maximum line speed will now be installed at locations similar to those at Santiago as well as ASFA transponders to limit train speed on the approach to sharp curves. The rules governing the use of cell phones by engineers will also be tightened.

There was an assumption that ETCS would be fully operational for all trains operating on the Ourense-Santiago high speed line when it was originally built. The double curves on the connection from the high speed line to Santiago Station were only supposed to be a temporary solution, as the new line was planned to be extended further north, but funds ran out.

This sounds similar to the situation that existed on the approach to London Paddington and the serious accident at nearby Ladbrook Grove in October 1999, where a train departing Paddington passed a signal at danger and collided almost head on with an approaching train. Here the designers of the track layout had assumed that all trains would be fitted with ATP, whereas only some trains had it installed and even then it was not always operational. The track layout has since been altered to reduce the amount of bi-directional operation, signal sighting has been improved, a national train protection and warning system has been installed to prevent trains from passing signals at danger, and all trains fitted with ATP can only remain in service if it is functioning correctly.

The possibility of the engineer not recognizing his location has also been raised as a reason why he failed to brake the train for the 50 mph speed restriction. Modern high speed lines often lack many of the distinguishing features of conventional railways, such as junctions and stations, to aid location recognition. The Ourense-Santiago line has 31 tunnels and 38 viaducts in just 54 miles. The simple expedient of erecting wayside signs to tell engineers where they are would help, especially when trains are operating under degraded conditions, such as ETCS not functioning.

Perhaps there should be better dissemination of the main findings from railway accident reports so that history does not repeat itself. This applies not only to train operators and signaling specialists, but also to those involved in designing new lines and track layouts. A greater range of scenarios needs to be considered, especially in situations where trains are operating under degraded mode. Never assume that people will always behave in a certain way, and try to expect the unexpected.

Finally, all railways need to be well prepared to handle the ramifications of an accident. This includes staying on top of the huge media interest that major accidents inevitably attract and providing a steady flow of accurate information about the accident and the inevitable disruption that follows to passengers and freight users. French National Railways (SNCF) was clearly very well prepared as its handling of the serious accident on July 12 at Brétigny-sur-Orge south of Paris was commendable. Others would do well to study and emulate it.