Network Rail has explained the cause of the landslip in the Harbury Tunnel cutting, which has blocked a section of the railway in Warwickshire.
The incident on 31 January means the line will be blocked “for several weeks”, according to a statement from the rail infrastructure operator last week.
Today, Network Rail provided an update on the situation to Jeremy Wright, MP for Kenilworth and Southam.
Karl Budge, route delivery director for Network Rail, said that his team had been working with contractor J Murphy over the past four months to address a persistent landslip problem on this section of the line, which dates back “20 or 30 years”.
He explained: “We had completed 75% of the work, when we started to find small cracks opening up in the slope above the cutting.
“We did an investigation, and found that there was 10mm of movement per day in the slope.
“Then we discovered a vertical fault at the back of the cutting. All the information we have on geology around this cutting, and all the geological maps of the area, had not shown this before.”
Carole Bayliss, senior route asset manager, added: “We are now reworking our design solution to address the problem.”
Wright said: “Hundreds of thousands of tonnes of earth and rock need to be moved. It’s obvious that work is progressing, but we all want the work to proceed as quickly and safely as it can.”