Precast concrete offered an affordable and convenient solution for the construction of a new rail over bridge with minimal disruption to rush hour commuter services.
The requirement for deconstructing the existing road bridge over the main trunk line and replacing it with a new structure while causing minimal disruption to the rail services called for an innovative approach that was only possible with precast concrete.
As there was no room for error, and delays would be extremely disruptive while incurring huge costs, the ability of precast concrete to provide a kit set solution was crucial to the success of the project which had to be completed within a 7 day window.
A full size mould of the bridge was constructed and each element of the structure was cast in this mould to ensure perfect fit when assembled.
Very large elements were cast to minimize assembly time and reduce the number of crane lifts and the number of joins where precise matching was necessary.
The three pile caps each weighed 67 tonnes. Thirteen wall panels were cast weighing between 27 and 45 tonnes and the ten deck units each weighed 49 tonnes.
A high degree of accuracy was needed to place 1100 grout sleeves, all to a maximum tolerance of 10 mm. Every component fitted into place without problems.
The project used 500 cubic metres of self compacting concrete and 140 tonnes of reinforcing.
The use of precast concrete provided the optimum solution of minimum construction and disruption time, and low maintenance permanent materials to ensure the maximum service life.
A short 90 second video of the units being assembled on site can be viewed on You Tube: