It will connect with the existing State Highway 1 and the future Ngaruawahia section north of Bern Rd, Horotiu, and is expected to reduce traffic congestion by directing traffic away from the existing road network.
Mr Young said opening the Gilchrist interchange was another exciting milestone for the project.
"Construction of the Te Rapa section has benefited from optimal weather conditions," he said. "As a result we are in advance of our construction schedule and look set to open the completed Te Rapa section of the Waikato Expressway to traffic before Christmas.
"This means we are now at the business end of this section of project when the public will begin to see major changes in their travel movements as we begin to move them on to the completed sections of highway."
Speed restrictions will be in place for the duration of the works which will be weather-dependant.
Electronic message boards will also be installed to display up-to-date traffic information and real time updates will be available on the Waikato Expressway Facebook page.
"We thank the public in advance for the patience they have demonstrated over recent months as we have four-laned Avalon Drive, and thank them in advance for any inconvenience these completion works will cause," said Mr Young.
WAIKATO EXPRESSWAY
* The expressway is about 100km long and will have four lanes with dividers to create two lanes in each direction.
* The four-lane section now ends near Te Kauwhata but will be extended to bypass Huntly, Ngaruawahia, Hamilton and Cambridge.
* It will then join up with the existing State Highway 1 south of Cambridge.
* It will cut travel times between Auckland and Tirau by 35 minutes.
* Its estimated completion date is 2019.