Balfour Beatty Civil Engineering Ltd

Britannia Bridge – Underbridge Number 165 (CNH3)

Bridge Management Strategy Commission

Britannia Bridge, originally a box girder structure built by Robert Stephenson in 1850, was burnt beyond repair in 1970. The replacement arch structure now carries both the railway and the A55, so is a key structure for Network Rail and the Welsh Assembly Government.

Birse Rail was commissioned by Network Rail to produce a 'Bridge Management Document' to plan the controlled maintenance of Britannia Bridge to facilitate the longevity of this sizeable and extremely complicated, Grade 2 listed structure.

The structure is formed from 61 road spans, and eight railway spans, with a mixture of construction techniques including steelwork arches, masonry and pre-stressed concrete. Examinations are difficult due to the size of the structure and access is hazardous, including risks from confined spaces, underwater examinations, working at height, and railway and highway traffic.

Streamlining the examination was a key requirement of the management document to try and reduce the length of examinations and the risks involved. This was principally achieved through a risk assessment of all the structural elements of the bridge to determine the structural elements that could potentially be inspected less frequently. A workshop with Birse Rail, Network Rail and the examination contractors was also carried out to determine the best way to manage future examinations.

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