Overbridge needs rebuild

DO OVER: The Norther Corridor's QE II Drive overbridge is being redone after it was discovered it had sunk in the weak ground.

Weak, soft ground has seen a bridge on the controversial $240 million Northern Corridor needing to be rebuilt.

The poor condition of the ground has been an ongoing issue with the project and although the New Zealand Transport Agency project team took it into consideration, the QE II Drive overbridge settled further than expected.

“The team has reviewed options to fix this and the best long-term option, which provides the greatest surety, is to deconstruct the walls, add new piles and construct the walls again,” NZTA portfolio manager Colin MacKay said.

“The very weak ground has caused the abutment walls to move horizontally slightly
more during construction than the design allows. The option
of installing additional piles
and reconstructing the walls provides the greatest long-term resilience.”

Mr MacKay said the redo would be covered within the
existing budget and it would still be on-track to open mid-next year.

“The team has the equipment, crew and materials already in place and they expect to finish the reconstruction of the bridge abutments and walls within the current programme and within budget.”

The issue was discovered
early and so was a solution, he said.

“The design and construction of the bridge is unchanged. This additional work will stabilise the ground beneath the bridge giving it good, long-term resilience.”

Further piling work at QE II Drive will start in August.

It comes as the Papanui-Innes and Linwood-Central-Heathcote community boards are recommending the city council take another look at traffic mitigation measures.

The motorway, which runs from the Waimakariri district through to Cranford St, is expected to boost traffic through St Albans by 30 per cent.

There have been a number of options suggested to off-set the amount including a rapid bus service, a high occupancy vehicle land and park and ride facilities.

The city council will make a decision on the recommendations in July.