Largely hidden from public view, one of the most visually spectacular features of the $2.4 billion Waikato Expressway is fast taking shape.
Work on the imposing Karapiro Gully Viaduct began late last year and already two 36 metre tall columns have been erected at the site.
The build is part of the $250m Cambridge section of the Waikato Expressway.
NZTA project services manager Peter Simcock said the viaduct would be 40-metres tall at its highest point.
It was the tallest bridge planned for the expressway and at 200m long, was comparable in length to the bridge that will eventually be constructed over the gully section at the southern end of the Hamilton section of the expressway.
The towering 36m columns had been constructed in six metre sections.
Construction teams were now focused on building the pier head on top of the two columns.
The viaduct will feature four spans and three piers.
Next autumn, contractors will start a vegetation restoration programme in the gully using native trees and plants.
Simcock said restoring the gully environment was required under the Resource Management Act.
NZTA was also mindful of mitigating the cultural impact of the viaduct build and had consulted extensively with iwi on the replanting.
Simcock said gullies were traditionally an important food source and travel route for Maori.
HEB Construction project manager Gary Budden said the viaduct was one of the most "visually spectacular" features of the entire Waikato Expressway and was being built largely out of sight from the public.
People can view the viaduct from Cambridge's Albert St.
From "an engineer's perspective" it was exciting to be involved in the viaduct construction, Budden said.
"It's always satisfying to build something like this and see it take shape."
The Karapiro Gully Viaduct is timed to be finished in June next year.
The Cambridge section is due for completion in late 2016.
Meanwhile, National MP Steven Joyce said his party was committed to finishing the entire Waikato Expressway by 2019.
The contracts for the Huntly and Hamilton sections were expected to be awarded next year.
Joyce said the expressway's $2.4 billion price tag was justified and its completion was crucial to unlocking the economic potential of the region.
"I can't think of any bigger project or one that is more important in terms of unlocking the economic benefits for the Waikato," Joyce said.
He said the region had a bad road safety record because its roads were not designed to take the volume of traffic they were experiencing.
"If you get the expressway running through from Auckland to south of Cambridge, to the east of Hamilton, then you'll get lots of people off the rat runs."
Green Party MP and transport spokesperson Julie Anne Genter said if the Greens were part of the next government, they would undertake a careful review of the entire Waikato Expressway project.
"Obviously there are a few people who think the project is going to be a very good thing for them and wouldn't like the idea of it being pushed back but I think New Zealanders want their tax dollar spent in the most sensible way possible," Genter said.
"I think we have to have a review because of the very low benefit-to-cost ratio the project has.
"The expressway has very, very low benefits for the amount of cars that it's going to serve."
Joyce said the Greens were on "cloud cuckoo".
"If you're going to get this done before the end of the decade then we've got no time to waste and we're well aware of that," he said.
- Waikato Times