Engineers have begun preliminary soil testing for the proposed eastern motorway in Tauranga.
A series of holes 600mm deep is being dug into the surface of State Highway 2 near Mt Maunganui.
Twenty-four test pits will be dug this week to investigate the soil under the existing road.
The New Zealand Transport Agency says it needs to know more about the materials involved before designing the new road surface.
Traffic speed will be limited to 50km/h during the works, which will be during the day but outside peak times.
