EJ Whitten Widening Scheme
COWI in JV with Arup and SMEC
Fulton Hogan (contractor) for Vic Roads
A 3.2km section of motorway was widened from two lanes to four in each direction, which extends to five lanes over the bridge. A new 518m long bridge was built in the central reserve gap between the existing structures.
The EJ Whitten Bridge on the M80 Melbourne orbital freeway, opened in 1995, had been designed for future widening through the provision of a third concrete box girder between the two existing ones.
Increased traffic loading and revised seismic criteria would have required significant strengthening to the original structure in addition to the new construction, had this original solution been adopted.
The skill of the engineering team which won the design/build tender meant that a revised solution, involving considerably less weight through the use of twin steel box girders, entirely eliminated the need for strengthening the original piers and foundations.
Optimisation of the design meant that both pierhead beam formwork, girders and precast deck panels could be installed using a travelling gantry, thereby maintaining full operation of the existing bridge while allowing safe working conditions for the extension works.
In addition, new vehicle and pedestrian safety barriers were installed without significant alteration of the supports through clever detailing and analysis. The revised scheme meant that the works were carried out at a cost of less than half the original client budget.