"It reduces the likelihood of getting stuck behind slower vehicles and subsequently making risky and potentially tragic decisions ... you are more likely to get to your destination sooner, and in one piece."
He said the agency would continue to monitor the impact of heavy traffic on the road.
The National Land Transport Programme has also allocated about $10 million over the next three years to improve the general condition of the highway.
The project furthers the Government's Safer Journeys strategy, which is aimed at preventing death and serious injury by creating a safe transport system through a combination of safe roads and roadsides, safe drivers, safe speeds and safe vehicles.
Other passing stretch work is taking place at Kopua Hill and several locations between Lake Tutira and Te Ngaru.