'A PLANNED approach to deliver a job of this scale would take more than two years. This has taken two weeks, ' regional manager for Birse Rail Mark Salt says. Birse Rail is the lead contractor brought in by Network Rail for the Cumbrian rail crash rebuild.
Engineers have been working at the site round the clock following the tragic derailment of the Virgin Trains 17:15 service from London Euston to Glasgow on 22 February. An interim study by the Rail Accident Investigation Branch (RAIB) revealed that the set of points at the site of the derailment were in a poor condition (News last week).
The possibility of criminal prosecutions has not been ruled out so reconstruction efforts had to be planned meticulously to ensure vital evidence was not disturbed. Director of operations at the site, Network Rail's major projects and infrastructure director Simon Kirby, began co-ordinating operations at the site just two hours after the disaster occurred.
'We sent a helicopter up to survey the site, ' he says. The results of this survey told the team that a new 1km road would have to be laid, wide enough to accommodate the two cranes - one 1,000t and one 800t - needed to lift out the nine derailed carriages. The nearest road, the A685, was neither close enough nor wide enough for the heavy plant to use.
Construction of the new route began two days after the accident. Kirby says that the main problem was the gradient.
To avoid any possibility of the low loaders used to take away the carriages getting stuck, the route had to be as at as possible. Unfortunately the attest route available cut through the fields of four farmers, and was interrupted by a hillock and a stream.
The hillock had to be shaved off and a temporary bridge built.
To further complicate matters, the stream contained the rare White Clawed Craysh, making it a Site of Special Scientic Interest (SSSI). The Environment Agency was drafted in to help ensure the crustaceans were safe.
The road itself was a prefabricated aluminium system laid by Eve Trakway, a rm brought in after the Potters Bar and Paddington crashes. 'There is a double layer [of aluminium panels], 6m wide at the bottom, 3m wide on top, for the access road. The road sits straight on the ground. Each panel is positioned to spread the weight, taking one vehicle axle per panel, ' says Eve's project manager Vinnie Jones. A total of 2,500 panels were taken to the site.
At the end of the roadway, next to the 60m of damaged embankment, Birse Rail set about building a 20m wide, 8m tall platform to support the cranes as they lifted the carriages. A massive 23,000t of granite fill graded at 150mm or less was delivered over a period of 108 hours. 'That was one lucky aspect: it all came from the Shap quarry in Cumbria, only 10km away, ' Salt explains.
At one point 25 trucks per hour were arriving on-site.
Another piece of luck was that the siltstone over bedrock in front of the embankment was a sound enough foundation to support the platform's mass.
'The foundation was very good.
All we really needed to do was strip the topsoil, ' says Salt.
Once in place, the two cranes, sitting at either end of the derailed train on the southern side of the track, could begin their work. Each carriage was moved with immense care to preserve any evidence. Carriages were lifted, and moved to a set-down area at the eastern end of the site, righted, and searched again. From there, they were lifted onto lowloaders. Once three low-loaders were ready, they moved off in convoy to take the carriages to the Alstom depot at Washwood Heath in Birmingham, for further investigation by the RAIB.
The greatest challenge lay in lifting the westernmost carriages that sat at the top of the bank. Their location meant the reach of the 1000t crane was not adequate to lift them and position them at the eastern set down point and so a complicated tandem lift was employed to pass the carriage from one crane to the other.
By Sunday the carriages had been moved and engineers could begin rebuilding the bank. 'The plan is to use as much of the rock from the platform in the permanent solution as possible, ' says Birse Rail's operations director Mark Jenner. Design regulations mean the rebuilt embankment must be up to 2m wider than it was previously. Only then can the track, overhead lines and signalling be reinstated.
The biggest single challenge has been logistical. Grayrigg has a population of 100-150 people.
The crash site has up to 400 people on-site every day, overwhelming the population and the facilities of the tiny community. Such a large job and so rapidly evolving, has to be broken up into manageable chunks.
'Each unit goes and does their work, and then reports back to co-ordination meetings every two hours, to discuss the work and progress, ' says Jenner.
The line is due to re-open on 19 March.
On site Network Rail Major Projects and Infrastructure (MP&I) Civils Birse Rail - lead contractor Ainscough - crane hire Allely's Amey - track lighting Cemex - aggregates Delta Rail Eve Trackway - road laying EWS recovery engineering First Engineering Metcalf Scott Wilson - geotechnical design Stent - track foundations WA Developments - civils/ groundwork