Once the improvement work is completed, passengers will benefit from a more reliable rail service in the Stroud and Kemble area. Work will begin next Sunday night and will be carried out round the clock into the small hours of 31 October.
Old capping beams will make way for new concrete ones – designed to last for the next 125 years, providing a permanent solution to secure the voids and to strengthen the rail tunnel.
Chris Rayner, route director, Network Rail said: “A complex scheme like this will normally take six to eight weeks, but we will be completing it in just under a week to minimise any inconvenience caused to passengers. We will also make full use of this six days to carry out strengthening work on the embankment wall near Kemble station.”
"We have recently held a series of meet-the-manager sessions with First Great Western and the feedback received are very positive. We would like to thank passengers for their patience and for giving us their support to carry out this work."
Measuring 6m wide by nearly 50m deep, these shafts were among the 10 built in the 19th century to allow workers to access into the hillside to construct the Sapperton railway tunnel. However, they were not backfilled and were instead capped off with a combination of concrete and timber after the construction of the tunnel was completed.
As these four shafts were built beneath the 1 3/8 mile long railway tunnel, track and rail ballast must be removed for engineers to access them safely. Road-rail cranes will be used to lift and install the pre-cast concrete beams, weighing 4 tonnes each, into the shafts.
An army of 100 men will be moving nearly 1,000 tonnes of materials and eight 25m-long track into and out of an inaccessible area.
Alternative train and coach services will be provided to rail passengers travelling between Swindon – Cheltenham Spa. Passengers are advised to check their journey time before they travel.
About Network Rail
Network Rail owns, manages and develops Britain’s railway – the 20,000 miles of track, 40,000 bridges and viaducts, and the thousands of signals, level crossings and stations (the largest of which we also run). In partnership with train operators we help people take more than 1.6bn journeys by rail every year - double the number of 1996 - and move hundreds of millions of tonnes of freight, saving almost 8m lorry journeys. We’re investing £38bn in the railway by 2019 to deliver more frequent, more reliable, safer services and brighter and better stations.