e-mosty December 2018 e-mosty December 2018 | Page 39

Figures 5 and 6: EJ Whitten Bridge before widening
WIDENING OF THE BRIDGE
In 2016, the widening of EJ Whitten Bridge was ten-
dered by VicRoads as part of the Sunshine Avenue to
Calder Freeway upgrade of the M80. With a Design
and Construct contract, all tenderers were free to
propose alternatives to the reference scheme of a
third concrete box.
The winning tender design incorporated twin compos-
ite steel boxes with an in situ concrete deck placed on
precast concrete slabs. The superstructure was sup-
ported on new pierhead crossbeams (as the original
intended) and made integral with the existing deck.
Advantage was taken of the presence of the existing
structure to place the steel girders with a pair of gan-
try cranes running along the cantilevers of the original
viaducts. The gantry cranes were also used to place
the precast deck panels and the formwork for the pier
crosshead beams.
The final design solution is shown in Figures 7 and 8.
The lighter weight of the superstructure elements was
a major factor in adopting this design. This resulted in
the elimination of any strengthening requirements for
the existing substructure.
The crosshead beams consist of in situ concrete sec-
tion built between existing pier columns, supporting
the new bridge superstructure. Both ends of the new
crosshead beams were made integral to the existing
pier columns.
The post tensioning ducts provided within the existing
piers were utilised as envisaged, and were sufficient
to provide the structural connection capacity between
the existing pier and new crosshead.
Figure 8: Typical section of actual widening scheme
Figure 7: Render of final widened configuration
4/2018