The wrougth iron Royal Albert Bridge
Royal Albert Revisited
by Clive Kessell
Linking Devon with Cornwall across the river Tamar, the single track Royal Albert Bridge is of strategic importance, being the only remaining mainline rail link into Cornwall. If it were to be out of action, then the Royal Duchy rail network would be cut off from the rest of the UK.
The bridge opened in 1859, the last great civil engineering project of Isambard Kingdom Brunel, and was constructed mainly of wrought iron. Modifications and strengthening was carried out by the GWR in the 1930s, primarily to replace or enhance the cross girders upon which the track is positioned using steel components. These had rendered some of the original Brunel girders redundant but they were kept in place to improve the rigidity of the structure.
Surveys had shown that, while the bridge was in generally good condition, some corrosion was present. A major refurbishment was scheduled, as reported last year by the rail engineer (issue 82, August 2011). This covers the central spans of the structure, including the removal of certain lower diagonals which were installed in the early seventies. One year on, it was time to visit the bridge again and see how work was progressing.
Various consultations had to be carried out before work could start. This was not only with English Heritage (the bridge is a Grade 1 listed structure) but also with the local communities since noise and potential damage from falling debris were perceived as real risks. With everyone onside, Network Rail and its principal contractor, Taziker Industrial (TI), could move forward with confidence.
Despite preconceptions, the bridge had been built to a restricted budget and the original plan for a double track railway had to be dropped on grounds of cost. The resultant single track bridge is therefore quite narrow which makes it more susceptible to side wind movement. Great care was needed to design an access system that did not worsen wind loading. The two main centre sections are linked to each shore by a number of approach spans, the ones on the Cornish side being on a sharp curve. The access system has thus to include these spans, much of which is over land rather than water.
to be continued