The Wreck at Paddington:
Preventing a Recurrence

Railway junctions are known in the business as "interlockings." At junctions where main-line tracks meet and cross, the numerous switches (points) have been interlocked to prevent the dispatcher from establishing a dangerous route. For many decades, railway signaling was a cutting-edge technology, one that introduced "fail-safe" design on a large scale. In railway signaling, no equipment failure should lead to a more permissive (dangerous) signal indication than would have been the case if the equipment had not failed. While signal and interlocking systems do occasionally fail in dangerous ways, this is a very rare event. The most common cause of railway wrecks is proceeding through a red signal, which appears to be the direct cause of Tuesday's disaster.

What could have been done to prevent this tragedy? Many things, in fact. Any one of the improvements listed below would almost certainly have prevented this wreck. Why had none of them been implemented?

• Just like highway junctions, major railway junctions must be elevated. Crossing traffic always carries with it some element of danger, and as long as trains routinely cross paths, there will be crossing accidents. (Building elevated junctions also greatly increases the capacity of the system, which is now sorely needed around London.)
• For decades, metro trains have been equipped with ATC: Automatic Train Control (also called ATP). ATC prevents a driver from violating a signal. It slows or stops the train as necessary to obey signal indications. Dangerous driver behavior is in principle impossible.
• The "high speed" 125 MPH Great Western train was diesel powered, carrying thus large volumes of diesel fuel, which is almost certainly what fuelled the fire that was fatal to so many. At the time of the wreck, the trains were operating under wires, so, in principle, neither train needed to have fuel on board. It is long past time that the UK electrified its principal rail services, as has indeed been done in most of the rest of Europe.
• Reports on BBC indicate that complaints had been filed by operators about the visibility of a specific signal, the running of which appears to have led directly to this wreck. Cab signaling was first installed more than half a century ago and is now common on railroads around the world. It eliminates the possibility of a driver missing a signal under difficult seeing conditions.

ALL of the above measures have been implemented on the French TGV lines.

There are other factors that may have contributed to the wreck and that raise two further issues to be addressed by the inquiry:

• How is it that the driver of the local did not see the oncoming 125 and stop short of the switch? The driver of the local had a year of training and a few months of experience. Were training or experience contributing factors? Experienced drivers always visually check the setting of switches and are alert to conflicting traffic. Why did the driver of the local fail to see the onrushing express and stop?
• Was there a functioning dead-man switch (also known as AWS) in the cab of the local? Had it been wedged? Do we know for sure that the driver was awake and alert? If not, why not?

We offer our sympathies to everyone touched by this tragic accident. Let us hope that some lessons will finally be learned and that those who were killed did not die in vain.

BBC has covered the Paddington wreck as thoroughly as circumstances permit and is the source of information specific to this wreck.

J.H. Crawford
7 October 1999

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