Network Rail’s sad winter of soggy earthworks continues as a landslip in a cutting has caused the closure of the railway between Tunbridge Wells and Tonbridge in Kent.
The area has seen more than twice the average monthly rainfall in January, on the back of a very wet December.
The cutting at High Brooms, where the line is cut around 10 metres deep into clay in the hillside, was built 160 years ago. The sides are very steep, as the Victorian contractors did not want to buy more land to allow a shallower cut, and their knowledge of soil mechanics was rudimentary. They also cut through a seam of Wadhurst Clay, which is very poor for constructing earthworks as it absorbs water and does not drain freely.
The result was a landslip in the early hours of Monday 1 February. This was picked up by remote sensors, which had been in place following two previous smaller slippages in the same area. Engineers investigated and found that there was a risk to the track and trains so took the decision to close the line.
Work is needed over the 150-metre length of the cutting to make a permanent repair and protect the railway from further slips. The line will re-open on Saturday, 20 February, allowing a full-scale and permanent repair to take place.
Fiona Taylor, Network Rail route director for Kent, said: “We looked long and hard at the possibility of opening the railway sooner. However, it is absolutely essential that our railway is safe to travel on and, by taking this extra time, we can reinforce and protect the line for years to come.
“We’ve had exceptionally wet conditions this winter, driven by climate change, and have suffered a number of landslips across the Southern region. This is a long-term challenge we’re facing and by taking another week to do this work, we can protect the line for generations to come.
“Thank you to our passengers and lineside neighbours for their patience and understanding whilst we carry out these critical works.”
A permanent fix is now being put into place. This will include re-grading the cutting faces (making them less steep), soil nailing and placing netting over the top to ensure no more slippage occurs. Over 5,000 tonnes of spoil will need to be removed from the site to make the repair.