Works were undertaken to regrade the embankment on the West Coast Mainline (CGJ7). The project involved the filling of 2 large gullies to enable the regrade and included importing circa 20,000 tonnes of engineering fill.
The site is situated in the Lune Gorge adjacent to the M6 motorway and the River Lune approximately 1500m south of Tebay Yard. The slopes are situated on sidelong ground with the motorway to the west and the river to the east. The earthworks consist of overstep (35 to 40 degrees) embankment slopes which are between 7 and 12m in height.
There is an over high ballast shoulder present and there are numerous smaller issues on the slope faces such as localised slumping and hummocky ground. The S&T troughing is tilted/disturbed in a number of places along the length of the earthworks in question.
20,000 tonnes
engineering fill imported
900 track way
panels used
To bring the earthwork from a poor to serviceable condition, the scope of works comprised of:
The first stage of the scheme was to install the haul road to access the site; this involved the installation of circa 900 track way panels due to the rural location of the site. At the site there were two large gullies present, hence to carry out the re-grade these required in filled/profiled with a toe berm to create a haul road from where the embankment re-grade could be carried out from and enable the shallower slope angle.
Once the toe berms were installed, the embankment within the railway boundary could be re-graded with 6B rock fill and the trough route aligned. Part of the design was to use the excavated material from benching to face the toe berms, this meant there was no requirement to take spoil off site. Part of the works were also to divert the existing drainage down the berms and formalise this into a new culvert to the outfall into the River Lune.
The project was able to celebrate success and demonstrate best practice within the following areas:
Network Rail
The project involved regrading approximately 280 metres of the embankment to enhance structural stability and improve rail safety.