This article originally appeared in RAIL magazine back in October 2023.

Built as a single track line by the Wycombe Railway and opened in 1879, the line between Princes Risborough and Aylesbury has always been a bit of a Cinderella line. Its only claim to fame was the fact it was the last place in the UK to run BR built Class 121 ‘bubble cars’ which were finally retired in May 2017, having been introduced to the line by Chiltern railways in 2003. However, thanks to the arrival of Phase 1 of High Speed 2, this sleepy backwater’s currently having a makeover. HS2 will pass under the existing line to the West of Aylesbury. To do so the EKFB Alliance and Network rail have closed the line from August 19^th until the 30^th October. The closure has allowed a culvert close to Aylesbury to be rebuilt and a new 1.8km long embankment and bridge to be constructed to replace the 1879 formation. To future-proof the line the new bridge can carry two tracks and the linespeed has been raised from 40 to 90mph. Unlike other bridges on or over HS2, this bridge has been built by sinking four 2.4m diameter piled piers to a depth of 57 meters, making them the biggest piers on HS2. Each pier took between 36-48 hours to pour.  Atop the piers sits a 100m long double-track width steel bridge which was built in 30m sections in the North-East before being transported South and assembled on site. To complete the work Network Rail has used 3000 sleepers and 14,000 tonnes of fresh ballast on the new alignment. A high-output track laying machine installed the rails over a single weekend. 

When I visited on September 25^th 2023 Colas Rail had begun tamping the new track ready for the lines reopening. Once tamping is complete 200 tonnes of check-rails will be installed on the bridge to mitigate against the chance of any possible derailment on the bridge affecting HS2 services.  Meanwhile EKFB had begun excavating the clay underneath the bridge to form the HS2 cutting which is exposing the top 8 meters of the piers. This bridge is unique amongst HS2 bridges in that it was constructed at ground level and then the ground’s being dug out from underneath it.

The excavation work’s being done in stages from the North to the South due to the proximity of the old railway formation which still carries fibre-optic signalling cables and has the disconnected track still in situ which will be recovered at a later date. On the South of the old formation EKFB are building the piers and deck of a road bridge over HS2 as passive provision for the South-East Aylesbury Link Road (SEALR) whilst another road bridge over HS2’s being built further to the North-West as part of another link road scheme. 

Future work to the line will see the half-barrier level crossing at Marsh Lane near Little Kimble upgraded and replaced with full-width barriers (which will allow linespeed improvements) and resignalling.

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