"The winter in the Waikato or in New Zealand, in particular, is just too wet and when you move earthworks you have to be able to compact it solid and you can't compact it solid when it's wet. You have to dry it out."
During the rainy season - workers will concentrate on preparing parts of the route which have already been excavated.
Mr Dickens says a majority of the project is in a valley where "no-one can see".
"The traveling public at the moment only see us building the Ohinewai end of the project. [The Huntly section] is 15 km long and the majority of it is through the mountains of the Taupiri range and no-one can see us building it."
The route is scheduled to be finished by December 2019.
It should ease the traffic congestion which currently plagues travellers to and from the Waikato region.
New Zealand Transport Authorities' Huntly Section Project Manager Kevin Johnson says once complete the Waikato Expressway will relieve congestion because the main route is better engineered.
"You'll have wider roads on a better alignment and angle."
Waikato District Mayor Allan Sanson says he's not concerned that the bypass could drain the life out of Huntly.
In fact, he see's it as a chance for Huntly to expand its residential and commercial industry developments catering for Auckland.
"These bypasses they actually unlock a town's potential - so when you've got a main highway or railway or something running through your town it does actually cause problems around expansion and having to deal with NZTA."
And Waikato's Road Policing Manager Freda Grace says the new expressway will make for safer journeys:
"The expressway will give reliability of the route. It's a much safer road, it means that when people do make a mistake, the outcome for them should be better for them if they do crash."
When completed - the entire Waikato Expressway is expected to shave at least 35 minutes of the journey from Tirau to Auckland.
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