In November 2000, heavy flooding caused the collapse of one of the capped shafts. Emergency work over a period of four weeks was carried out to stabilise the collapsed shaft and similar preventative work was carried out on some of the other shafts; the four larger shafts, however, were left untouched. An erroneous report attributes the damage to the collapse of the canal tunnel running underneath; in reality the canal tunnel is to the north of the rail tunnel and does not pass underneath it. In 2001 it was decided to test the redundant beam remaining from the 1950 operations to destruction in order to determine its strength, as part of surveys intended to discover whether the route would support the loadings required for a route availability index of 8. It was found that the concrete had deteriorated and would not support the loads required for an index of more than 5. Further stabilisation was therefore required as a matter of urgency. The operation was carried out under a complete possession over a period of seven days by over 100 people working 12-hour shifts, many of whom were accommodated in temporary buildings at the site. Road-rail plant was used, standing on one track of the double-track tunnel to remove the other track and replace the beams underneath. The 1950 beams were cut into three sections using a diamond-tipped saw blade to facilitate removal. Each pit was then spanned with new prefabricated beams, one main support beam under each rail plus additional spacer beams to fill the gap between them. The new beams were fabricated in three sections to avoid exceeding the working load of the plant, which were joined once the beams were in place using stainless steel bolts. After work on the one track was completed, the road-rail plant was put into road mode and driven onto the new beams from where it could work on the other track. Not until the old beams were removed did it become known that the pits had indeed been backfilled in the course of earlier work and the fears of falling into a six-metre hole were unfounded. The seven-day possession did not give enough time to fully stabilise all four large shafts. Priority was given to the two least stable ones and the work on those was completed, but the remaining two were only partially stabilised, the beams under the up line