Staying on the rails

The rail industry is investigating methods to improve the design of trains in a bid to keep them upright and in-line in the event of a collision.

The Rail Safety and Standards Board (RSSB) is launching a research project to investigate the behaviour of trains in collisions, with the aim of improving their overall crashworthiness.

The project follows this month’s crash at a level crossing near the village of Ufton Nervet in Berkshire, where a First Great Western train travelling at 100mph collided with a car parked on the track. Seven people died and 37 taken to hospital. This week another train, carrying 50 schoolchildren, hit a level crossing barrier at Rowston in Lincolnshire, but did not derail.

As part of the project, researchers will investigate the design of coach couplers and bogie retention straps, and will consider previous accidents and their resulting inquiry recommendations, said Ray Ford, RSSB vehicle specialist.

The project is about preventing a train going out of line. If we can keep a train in line, we can predict what will happen inside that train, and therefore when we designprotective measures to prevent passenger injury, we know what we’re protecting passengers against,’ he said.

Such measures include improving seat design inside the carriages to protect passengers from severe injury.

Couplings keep coaches together in the event of a collision, and are designed to help prevent a carriage rolling over using resistance from the connected, upright coaches. The more coaches that begin to roll, the more difficult this becomes.

But it is now believed that to allow more energy to be absorbed, the flat surfaces at the ends of the coaches need to be allowed to come together, whereas in the early stages of an accident the couplers, despite an in-built collapse mechanism, keep them apart. So the project team hopes to improve the performance of the couplers by altering their design to allow the section of the device located inside the underframe of the coach to slide backwards, said Ford.

‘The coupling is still effective, because it is retained inside a tube; so it still attempts to stop the coaches rotating and ensuring they stay in line. but instead of keeping them apart, it allows them to come together,’ he said.

An anti-overriding device, specified on the most recently-built trains, would then lock the carriages together, preventing one rising up and coming down on top of another, with the obviously catastrophic consequences for people inside.

The researchers will also attempt to settle questions over the use of retention straps to keep the bogies attached to the coaches in the event of a collision.

These straps were investigated by AEA Technology in the wake of the 2001 Selby disaster, over concerns that they contributed to that derailment by lifting the bogies off the track after the body of the train rose up over the engine block of a Land Rover that crashed on to the track. ‘There is a school of thought that says if the bogie is no longer part of the train, then it is not additional energy connected to the train itself that has got to be arrested. On occasions where the bogies have left the train, there are very few instances where there have been casualties,’ said Ford.

But the straps could help to keep the train on the track in some collisions, said Jim Lupton, head of engineering research at RSSB.

‘It could be best to keep the bogies retained, so the vehicle can remain upright and in-line.’

The researchers hope to finally settle the debate, he said. ‘But there might not be an easy answer; it might be that in one case the answer is yes and another the answer is no. Then we would have to make a risk-based judgement.’