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Changing platforms Rail blockades are always testing times for contractors. Dave Parker reports from one site where everything went to plan.

Monday 26 January, 6.15am. The first Marylebone-bound train for nine days pulls out of Haddenham & Thame Parkway station, dead on time. Joint venture contractor Laing GrantRail site personnel heave huge sighs of relief. A new six car platform is open and the track re-aligned over a 7.5km length.

The station remodelling forms just one part of a £13M Railtrack project to convert the single track line between Bicester North and Princes Risborough back to twin track working. The station, opened in 1987, was a major bottleneck, and the contractor had only nine days to clear it (NCE 22 January).

'The station was built after the Beeching cutbacks in the 1960s and the old platform was where the down line now is,' explains Laing GrantRail contract manager Andy Pearson at the end of the nine day endeavour. 'By 17 May there will be two new platforms, a footbridge and shelters - but the priority was to get the old platform out and the track realigned.'

Bi-directional working with one train an hour in each direction has been the norm on this line for decades after the up line was torn up during the Beeching cuts. Chiltern Railways plans to increase services to every 30 minutes from May, which means relaying the old up line. However apart from the station platform, all the remaining structures on the 30km stretch are still capable of taking a second track.

There will be significant re-alignments to ease some of the tighter curves on the original line, Pearson says. 'The current speed limit is 120km/h. After we finish this will go up to 145km/h at least, maybe 150km/h.'

Continuously-welded rail will smooth the ride and concrete sleepers are used throughout - a total of 46,000 along the 30km stretch. There will be 140,000t of new ballast as well. In most areas the contractor has only to remove the old ballast, replace drainage where necessary and put down a sand blanket before placing the new material. Some of the formation will need attention but luckily, Pearson says, most of the embankments and cuttings are in reasonably good condition.

'We have to do some soil nailing and in places we're replacing the top 1.5m of embankments. A few places need berms or gabions to stabilise slopes, but it's nothing major.'

Most of the existing track can be slewed over to its new alignment, using nine French-built hydraulic machines. The contractor pre-laid 3.5km of new track on the new alignment, then slewed 4km of the old track during the blockade to complete the realignment. The new formation each end of the station was also prepared in advance.

Work actually began on the new station platform before Christmas, Pearson reports. Most of the brick walls and around 50% of the precast planks that top them could be positioned behind the existing platform without disruption to rail passengers or services. Once the old platform had been demolished the rest of the pre-cast planks were placed and the insitu concrete topping poured.

This arrived by road, in truckmixers, unlike most of the materials on the contract. All the ballast, sleepers and new rail is being delivered by rail. Waiting to receive them is a fleet of specialist engineering trains, including tracklayers, tampers and ballast regulators.

The new signalling is also the responsibility of Laing GrantRail. Pearson says the final set-up will still permit bi-directional working of the re-aligned track, while the new up line will be strictly one direction.

By the final Saturday of the blockade, the workforce was up to 250, most concentrated at Haddenham & Thame Parkway station. Work continued until 5.35am on the Monday morning, when the blockade was formally handed back to Chiltern.

By the time trains start using the new up line the station carpark will have been extended. All in all, Chiltern and Railtrack will be making a major effort to attract new passengers. It is to be hoped that local residents will take advantage.

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