Published 10th April 2013
A cement mixer lorry fell off a bridge onto a South West Trains (SWT) Class 455 service near Oxshott on November 5, 2010 seriously damaging the train. Due to the good design of the train, only five people were injured but the accident resulted in the loss of a four car Class 455 train which was based at the SWT Wimbledon depot.
So why did it cost what seems to be a hugely expensive £1.6million rebuild the carriage at Railcare’s Wolverton Works? After repairs, the train is set for trials and then back into revenue earning service helping to ease overcrowding on SWT trains via Clapham Junction.
A electric train carriage costs around £1m to build so spending £1.6m becomes a sensible piece of business when it means that SWT has got a four car unit back for service and a these trains always run coupled together making an eight car train. So for its money, they get a proper length commuter train back in service and the insurance claim is ongoing with the lorry’s insurers.
The accident is thought to have been caused by a tyre blow-out making the lorry carrying 24 tons of cement, veer off the bridge onto the train crushing motor coach No. 62838.
All four carriages on the train were damaged and one carriage was a write off having suffered severe damage. The other three carriages underwent a comprehensive rebuild and the written off carriage replaced with a long withdrawn from service vehicle.
The decision to rebuild the train followed a long decision making process by structural, mechanical and electrical engineers from Railcare and Atkins had agreed how to remove a large diagonal twist to one of the carriages.
The replacement vehicle availability from a Class 210 diesel train made the scheme viable and a carriage was used as a ‘donor’ vehicle to be rebuilt to a Class 455 specification. SWT and Railcare, (who have captured around 80% of the train accident repair market), had to ensure that qualified structural, mechanical, electrical and welding engineers were available to carry out the work over a long timescale and that workshop space was also available at Wolverton.
Because material alterations were being made to the 30 year old carriage, safety approval had to be sought via the vehicle acceptance process and the Rail Regulator’s office. A key stage was how to overcome the fact that the sole bar from the donor vehicle was 6mm, 2mm less that the class 455 so an extra 2mm was built up to make them compatible. The air suspension bolster holes were also in the ‘wrong place’ by 50mm and had to be reworked for safe passenger operation.
The Class 210’s headstock and dragbox could not be used with the Class 455 and had to be significantly altered but fortunately, a dragbox from the damaged carriage could be reused. The cab-end of the class 210 donor vehicle had to be cut off to convert it to what is known as an ‘intermediate end’. This also required complicated structural alterations to maintain the train’s crashworthyness.
The damaged train arrived at Wolverton on January 21st 2011 and the repair work did not commence until January 2, 2012 until the suitability and feasibility investigations had been carried out. The repairs were completed on March 28 and it has returned to Wimbledon depot for traction tests, trial running and final certification and should be operating passenger services in late spring.
Christian Roth, Engineering Director for SWT said: “The Oxshott accident posed a significant problem to us, as suddenly we were a train down. From an engineering perspective though, it offered an almost unprecedented challenge to rebuild a massively damaged train and safely take it back into passenger service. The expertise of the engineers who worked on this project is second to none and this is a fantastic achievement. We are now looking forward to the final testing phase before reintroducing it into service.”
Railcare’s Projects and Engineering Director, Phil Mitchell said: “The challenges of taking one kind of vehicle and making it into another are significant. Not only are you undertaking a significant repair but ensuring that all aspects of the newly built vehicle comply with the design and build specification of the Class 455. We are really pleased with the outcome of this complex project and look forward to supporting the test phase and seeing the train back in passenger service”.
Two Class 210 DEMU's were built by British Rail at Derby in 1981 and underwent tests and commissioning largely undertaken routes out of Paddington. The design speed was 90mph and performance was targeted to equal the Class 317 EMU. No. 210001 had four cars while No. 210002 had one car less and they also were equipped with different engines and electrical equipment, one a 1,125hp Paxman and the other had an MTU 1,140hp unit. These large engines took up a lot of passenger space so the project was discontinued and the trains withdrawn after eight years service.
Some of the carriages were used in developing the Class 457 Networker development train and after being in store at Eastleigh other vehicles were scrapped.