Railway Engineering Works at Box Tunnel, Bathampton Junction and Sydney Gardens, Bath

Transcription

1 Railway Engineering Works at Box Tunnel, Bathampton Junction and Sydney Gardens, Bath The plan to electrify the Great Western main line between Bristol Temple Meads and Airport Junction so that high speed electric trains can replace the existing Intercity 125 High Speed diesel requires a massive amount of engineering work to take place. Currently the only electric railway on the Great Western main line is between London Paddington and Airport Junction near Reading. The type of electrification installed is the overhead line (OLE) type. At no time in the past have any serious plans made it off the drawing board for electrifying the line as far West as Bristol. So all the existing railway infrastructure has no provision for any of the requirements that are needed for OLE. Network Rail has already been busy rebuilding existing road over railway bridges in order to provide the necessary clearance so that the overhead line electric wires can be installed. Page 1 of 7

2 Box Tunnel, West portal However, between Chippingham and Bath Spa there is a long tunnel. Located near the village of Box, this tunnel which is 3212 yards long nearly financially crippled the Great Western Railway company when the line was built. It is of course Brunel's Box Tunnel. Page 2 of 7

3 From the West portal, the height of the entrance of the tunnel looks huge. However, once inside, the roof quickly drops down to a height just above the top level of the trains. Leaving no clearance for the new OLE. The railway civil engineers looked into a number of options. The only practical solution was to lower the track. However, there were still some problems that had to be investigated and solutions found. Inside the tunnel there is an underground river that flows under the trackbed (from one side wall of the tunnel to the other side wall). The is also an underground subway that links the nonrailway passages, again this goes under the trackbed. There was very little information about both of these structures, so investigations had to be carried out to find out if they the track lowering could still go ahead. In addition, for about a quarter of a mile, there are some railway telephone and signalling cables that run under the trackbed. These are vital to the operation of the railway. As it was not practical to move them. New cables had to be provided. Because of the limited amount of space, the large semi-automated machines normally used to perform this type of track work could not be used. Instead all the old track (steel rails and concrete sleepers) had to be removed. Then bulldozers could remove the limestone ballast formation. Once the old ballast had been removed, new ballast was provided and formed to the correct level. Then new concrete sleepers and new steel rails were installed. At Sidney Gardens, Bath, there are some shorter tunnels. The track also needed lowering here as well. Page 3 of 7

4 Sydney Gardens West Tunnel Page 4 of 7

5 At the same time, the railway wanted to make maximum use of the time that the line was shut. So included in the project was the relaying and renewal of nearly all the points at Bathampton Junction. Again, the old rails and sleepers were removed. The old point machine were removed. New ballast was provided to replace the old. New point machines were installed on the new points. In total, ten new points were laid in. Some of the new points were in slightly different positions. Page 5 of 7

6 Bathampton Junction, looking towards London Also in amongst this all this work various sections of plain line were also relayed. Nearly every engineering train in the country was involved. Were there some problems? Yes, but only minor issues. Despite the scale of the works, it was all completed on time. So the first booked train service to operate after the works were due to finish ran on time with no problems. There are more pictures on Facebook here: Tunnel/ ?fref=ts Page 6 of 7

7 Bathampton Up Loop, looking towards the main junction Page 7 of 7