A REPORT by the Rail Accident Investigation Branch (RAIB) has blamed contractors for triggering the partial collapse of a bridge over the Midland Main Line at Barrow-upon-Soar on August 1, 2016.
Engineers from a Network Rail contractor, performing core sampling work to investigate recent subsidence on the bridge’s footpath, disturbed a pressurised water main, causing it to rupture and overload the masonry wall, dating from 1840. RAIB reports that although a slow leak was responsible for the footpath subsidence, it was not enough to cause the collapse until the cast iron water main was disturbed.
A full-height vertical crack in the wall also contributed to around 200 tonnes of debris falling onto the Up and Down fast lines of the MML at around 23.50. Fortunately no trains were in the vicinity, although the line was open to traffic at the time. No one was injured in the incident. Although the line reopened to trains 24 hours later, the bridge remained closed to road traffic until repairs were completed in March this year.
RAIB’s recommendations to Network Rail include a focus on greater competence of its staff and contractors, and the availability of information to enable them to manage the potential risk to its structures from breaches of water utilities, plus the provision of appropriate engineering input to risk assessments for intrusive investigations and masonry repairs on bridges carrying water services.