Bridge Repair Works

thumb_old_stoke_bridge2Old Stoke Bridge is a single span bridge that carries one carriageway of the A137 over the tidal section of the River Orwell near the Haven Post area, Ipswich.

Constructed in 1924 its main longitudinal members comprise 2 No. reinforced concrete tied arch trusses.

The deck is made up of transverse reinforced concrete beams that frame the bottom chords of the trusses with a thin reinforced concrete slab between the transverse beams. Reinforced concrete beams cantilever out from the bottom chord of each arch truss to support footways and services. The footways carry 1.07m parapets in reinforced concrete.
The clear span is 19.288 m with transverse centres between the arch trusses of 9.246m. The carriageway is 8.23m between the arch trusses carrying two lanes of traffic and the footways are 3m on each side. There is a parallel bridge carrying the opposite traffic flow separated by a narrow services bridge.

Construction work carried-out by Topbond included :-

The use of a moored jack-up barge to access the underside of the bridge deck.
Removal of deteriorated concrete by hydro-demolition and hand tools.
Cleaning by water jetting of the exposed areas.
Application of anti-corrosive paint coating to exposed reinforcement.
Hand-trowelled replacement of damaged concrete with approved concrete repair compounds.
Cleaning of the whole deck soffit and application of a new protective coating.
Repair, repointing and void filling of damaged brickwork on the adjacent Quay Wall.

Temporary works near the riverbank required Environment Agency approval and the restriction of the river hydraulic cross section to be minimised.