Project profile.

Brief:

Bridge Replacement over the Mersey River

75m long, three span, two lane bridge using Super-T Beams.

Contractor: VEC Civil Engineering

The previous timber bridge was washed away in the June 2016 floods. Engineering Edge designed a replacement 3 span, 75m long, two lane bridge which was built on steel piles and consisted of precast pier blocks, precast super T-beams and insitu deck. The bridge was raised in the middle span to increase the waterway capacity. The bridge also has an allowance for a stock fence to be installed to allow cows and traffic to use the bridge simultaneously.

challenges:

Constructing two piers in the river which had just washed away the previous bridge.

the rare innovation:

The piers were designed to be founded on driven steel piles to resist the vertical and horizontal forces and then vertically stressed concrete blocks were used to remove the need for formwork and access into the river. The central span was lifted to increase the flood opening and reduce the forces on the bridge.

key benefits:

Increased quality control from the precast operation, as well as a combination of integral abutments, bearings at the piers but continuous deck to allow the bridge deck to act as a diaphragm in ultimate flood conditions rather than relying on the pier acting as a cantilever.