CityEdge Alliance opens its tallest bridge
Oct 05, 2018
The tallest of 17 bridges being built as part of the Hamilton Section of the Waikato Expressway is now open to traffic. The Kay Road Bridge provides a key connection to Hamilton’s north-east suburbs, and at 18.8 metres high, it is roughly two times the height of the other bridges being built by the CityEdge Alliance.
Before the team could construct the bridge structure, some crucial work had to be completed below the ground. This included the excavation of 144,000m3 of soil to cut the expressway route through the Kay Road ridge—the biggest single excavation on the project.
To create a foundation for the bridge columns, the team installed piles 20 metres deep into the ground. Ground improvements were complicated by the discovery of unexpected slip planes and a redesign of the Continual Flight Auger (CFA) ground improvements was carried out. This resulted in 330 CFA piles being installed to strengthen the ground and prevent liquefaction in the event of an earthquake.
Construction of the three-span bridge above the ground involved building two pairs of 15 metre high concrete columns, bridge abutments, along with backwalls and other concrete elements, and two crossheads weighing 110 tonnes each. Twenty-one super-tee bridge beams, which are 30 metres long and weigh 50 tonnes each, were placed them on top of the crossheads.
Instead of building the two crosshead beams in situ, the team built the beams on the ground and placed them into position using a 350 tonne crane—this innovation saved time and money. The team poured the concrete deck, bridge barriers and guardrails and installed services under the bridge deck, including water mains and ducting for electricity, phone and internet cables.
A blessing from Waikato Tainui
Sixty staff from the Alliance, which is made up of the NZ Transport Agency, Fletcher Construction, Beca, Higgins, Coffey and Hick Bros, joined with tangata whenua from Waikato Tainui for a blessing prior to the new bridge being open to traffic.
Speakers from Waikato Tainui honoured the people who built the bridge, and revealed the new name for the bridge, Wairere ki Haua, connecting the key hapu in the area; Ngaati Wairere and Ngaati Haua.
“It is a great project milestone to open the Kay Road Bridge to the public," says Alliance Project Manager, Matt Fairweather. "The team worked together to come up with clever ideas for how to deal with the particular geotechnical challenges in the ridge."
The bridge itself has seen some great innovation too, and the team should be proud of the fine looking structure that they have produced.
The Alliance team has now opened five of the 17 bridges to traffic and one bridge to construction traffic. The Hamilton Section of the Waikato Expressway is scheduled to open to traffic in 2020.
Kay Road Bridge facts:
At 18.8 metres high, the Kay Road Bridge is the project’s tallest bridge—other bridges are typically 8 metres high to provide the required 6.1 metre clearance for vehicles on the expressway.
The 90 metre long, two-lane bridge carries traffic over the expressway along Kay Road.
The bridge itself consists of 3320 tonnes of concrete and reinforcing steel.