Concerns that the design of the passenger train involved in the Selby rail disaster could have been a factor in the crash were not addressed in the official report on the accident, it has emerged.
The GNER 225 that derailed in the accident and hit an oncoming freight train was powered by a locomotive at the rear with the driver in a lighter driving van trailer (DVT) at the front.
Some within the rail industry claim these trains are more likely to be derailed in a high-speed collision because the DVT is not as heavy as the locomotive, or because the train is being pushed rather than pulled.
But the interim report of the Health and Safety Executive, and its more recent study into the dangers of road vehicles obstructing railways, make no mention of the controversy surrounding DVTs. And there are still widely conflicting views among rail engineers as to whether the trains are more likely to derail.
Dr Ronald Thomson, lecturer in mechanical engineering at Glasgow University, said the 225’s power car is heavier than the trailer coaches, and its traction with the rails is greater. So when the train is braking, the locomotive can be more effective at the back, but when accelerating, the opposite is true.
He said: ‘Think of a trolley and a piece of rope. To start it moving, it is better to have the rope at the front, so you can pull. to stop a moving trolley, it is better to have the rope at the back to pull.’
In an accident where the train driver does not have time to apply the brakes, having a weight behind a lighter car, as was the case at Selby, could be a problem, he said. At Selby, where there was no more than a minute between the Land Rover ending up on the track and the final impact between the two trains, the driver had no time to react.
Concerns about the safety of DVTs have been raised since an accident in 1984 at Polmont, between Glasgow and Edinburgh, when a ScotRail vehicle was derailed after hitting a cow. But not all engineers agree on the potential risks.
Richard Gostling, technical director of the Railway Industry Association, who looked into DVTs following Polmont, said lack of weight rather than the force from the locomotive at the rear is the main problem. ‘The chances of derailment are greater if the vehicle at the front is lighter, as there is less weight keeping it down.’
As a result of Polmont DVTs were required to be 50 per cent heavier than passenger carriages, but they are still one third lighter than locomotives. Obstacle deflectors have also been fitted to all high-speed trains, with a shallow enough angle to sweep most things out of the way, said Gostling. ‘Sadly in the case of Selby, the train hit a Land Rover, which was too big an obstacle to be deflected, and it derailed.’
With the deflectors ineffective in this case, it was difficult to determine whether the lighter vehicle at the front, and the heavier locomotive at the rear, would have had an affect on the Selby crash, he said.
However, one rail engineer disagrees. Dr Felix Schmidt, senior lecturer in railway engineering at Sheffield University, said: ‘There might be a bigger risk of derailment if it is hit from the side.’
But at Selby a locomotive at the front of the train would probably still have derailed, he added.
A spokesman for the HSE said concerns had been raised over DVTs, but was not aware of any evidence to suggest the accident at Selby would have been any different had the train not been driven by a DVT.
‘The conclusion was that there was unlikely to have been much difference. It was a complicated scenario,’ he said.
The DVT became derailed 15m south of the impact, and it then travelled in a derailed but upright condition for 700m until it reached a set of points, at which it was deflected further in the direction of the other track. The express then hit a freight train, running 20 minutes early on the opposite track.
Is this high-speed heavyweight a saving too far?
Using locomotives to push trains is relatively uncommon, and most high-speed lines use engines at both ends to push and pull at the same time.
train operators also use double-ended locomotives which can be run to the other end of the train for the return journey. Trains on the German ICE high-speed line have a locomotive at both ends to prevent derailment as do the French TGVs. The same is true of the UK’s Intercity 125.
A single locomotive and a DVT were first used under BR, when an engine was developed capable of generating over 6,000hp, more than enough to drive the train. The 225 locomotive, which GNER operates on the East Coast Main Line, pulls the train from London to Scotland, and pushes it for the return journey.
One engine is obviously cheaper than two, and fitting another power car to every train or uncoupling the locomotive and driving it to the front, would mean a huge cost to GNER and a considerable disruption to timetables.
The other problem is that the 225 is not double ended, which means a turntable would be needed at each terminus to get it facing the right way for the return journey.
A spokesman for the train operator confirmed the train involved at Selby was being pushed by a locomotive at the rear, with a DVT at the front. But he denied this was the cause of the train’s derailment.