David Greenway: A tricky and possibly expensive operation

Published on Wednesday 9 June 2010 13:22

EACH derailment will create a unique situation that demands huge thought and skill to recover the vehicles.

In cases like Cruachan, access for special equipment is very limited and extremely expensive, and the engineer will have to select cranes that are large enough to reach from the road to where the vehicle is resting.

It is highly likely cranes sourced from specialist contractors would have the benefit of being versatile and can be brought quickly by road. This is of paramount importance if the train is in a situation like this.

If the access is really difficult and a crane can't be used, then freight haulage companies would be contacted for air-bags to prop the carriage until jacks and winches are used to move it.

A train, such as one involved in Sunday's incident, would weigh circa 45 tonnes, so it would be necessary to find a crane able to lift 100 tonnes or more, as reaching without the jib creates a leverage effect that reduces the weight the crane can lift.

This alone could cost something in the region of 100,000.

On top of those difficulties, the engineer must satisfy himself the ground on which he places the crane is safe for the total weight of crane and vehicle – a road supported on piers will need a lot of bracing and load-spreading beams to stop the crane's balancing outriggers from punching through.

Once the train is back on the road, it will be transported by a low-loader road vehicle to a workshop.

David Greenway is from the Institution of Mechanical Engineers' railway division.