Work linking the Huntly and Ngaruawahia sections of the Waikato Expressway will mean a major road layout change at the Gordonton Road interchange at Taupiri from February 12.
The south-bound access lane which takes SH1 traffic on to the Ngaruawahia section will close to enable a full interchange to be constructed as part of the works on the Huntly section.
With the lane removed, traffic will need to use the roundabout above the expressway and take the on-ramp.
The change will be signposted, and will add only a minute or two to journeys.
NZ Transport Agency Delivery Portfolio manager Peter Simcock says works are progressing well on the 15.2km Huntly section.
"The long dry spring and early summer has been great for earth-moving, and the project is on track for a 2020 opening," Mr Simcock says.
Two of the nine bridges needed are now open to construction traffic and work is well under way on the other seven.
"Getting started on linking the two sections at Gordonton Road is a milestone for the project team."
The Huntly section runs from the Ohinewai to the northern end of the Ngaruawahia section of the Waikato Expressway.
When completed it will take SH1 east of Huntly town and over the Taupiri Range.
When completed the expressway will improve safety, reliability and reduce travel times and congestion on State Highway 1 by delivering a four-lane highway from the Bombay Hills to south of Cambridge.
The expressway is being built in seven sections.