Bridge already cutting a dash

22:09, Nov 06 2012

It has yet to be officially named but the new Waikato River bridge taking shape north of Hamilton is already making a statement.

The 140-metre-long bridge is a key feature of the $250 million Ngaruawahia section of the Waikato Expressway and will take traffic over the Waikato River about 400m upstream of the Horotiu Bridge.

The bridge features four distinct V-shaped shaped piers which are taking shape next to the banks of the Waikato River.

Commuters passing over the Horotiu Bridge can see glimpses of the construction but the roadside view only hints at the progress being made on site.

As well as being aesthetically appealing, the pier design is also a response to resource consent conditions which require all the bridge supports to be outside of the edges of the Waikato River watercourse.

By using V-shaped piers that overhang the river, designers have been able to reduce the clear span across the river down from 76m to 55m.

The reduction makes it feasible to use steel beams for the bridge superstructure.

NZTA Waikato Expressway principal project manager Richard Young expects the construction of all four piers to be finished by early next year.

"The southern and northern embankments of the bridge are under construction. The embankments on either side of the bridge have been built up high, above the finished road level. This is done to weigh the embankment down so it compresses the ground below," Mr Young said.

"Once the embankment is sufficiently compressed, about five metres of fill will be removed so that the foundation for the bridge piles can then be constructed."

Twenty-three tonnes of reinforcing steel and 90 cubic metres of concrete go into each pier.

Bridge beams will arrive on site in January and will be assembled on the southern approach embankment before being "launched" across the river.

The launch operation is expected to be completed in April. Once the beams are across the river, the precast concrete panels will be lifted into place by a crane before construction begin on the final concrete deck and barriers.


Waikato Times