 A subsequent investigation by the British Geological Survey showed the road has had a history of subsidence-related long-term closures dating back to the 1930s, including a 1970s project that attempted to strengthen the layer below the tarmac with local rock fill.The road reopened in February, but with temporary traffic lights at the point of the slip restricting traffic to one direction at a time.In 2012 the road had to be closed several times for resurfacing and strengthening.