Waterproofing work on the 15-arch Stanway Viaduct has unveiled an unpleasant surprise for the management of the Gloucestershire Warwickshire Steam Railway (GWSR).

During work which started in early November, workers discovered an open joint in the parapet brickwork where the mortar bond had failed.  The defect, which is several courses below the base of both parapets, only came to light after ballast and other materials were removed.  The recently-exposed brickwork has not been visible since British Rail days.

The waterproofing project started following the success of the Gloucestershire Warwickshire Railway Trust’s Stanway Viaduct Appeal, which sought to raise £1.5m. GWSR is part of the former Great Western Railway line from Cheltenham to Birmingham via Stratford-upon-Avon and today runs heritage services between Cheltenham Racecourse and Broadway.

Dr Graham Plant, the GWSR’s Civil Engineering Director said: “This has come as a very unwelcome surprise. But we should be grateful that is has been found because we can do something about it. Otherwise it would have remained an unseen and worsening problem.

“The evidence suggests that movement has been happening gradually over many decades and certainly back to when the viaduct was carrying a heavily-used double-track main line. In addition to the waterproofing works, the brickwork supporting the parapets must be stabilised and we will be monitoring the structure for any further movement both now and in the future.

“We are considering a number of potential solutions which take into account personal and structural safety, engineering, cost, time and, of course, careful conservation of this 120-year-old heritage structure.

“It is of course important that we safely complete repairs for the long term and for future generations to enjoy. Unfortunately it may take completion of the project beyond the originally-planned February 2024 reopening as well as significantly adding to the cost.”

Philip Young, Chairman of the railway’s Trust, added: “We are very grateful to all those whose contributions have enabled the work on the viaduct to begin. Given that the repairs will now cost rather more than expected, now would be a good time for those who have not yet donated to do so, in order that these unexpected works can be completed and the line to Broadway re-opened as soon as possible.”