There’s been an early-February milestone at the Te Ara o Te Ata – Mt Messenger Bypass project in North Taranaki.

Work has now begun on the tunnel which is an important part of the $280m Bypass project, contributing to a much more resilient stretch of State Highway 3.

A 110-tonne road header machine is being used to excavate the project’s 235-metre tunnel.

Road headers have boom-mounted telescopic cutting heads, making them ideal for diverse geological conditions. A shovel plate at the front of the road header collects the excavated rock and soil, which is then conveyed via a belt to dump trucks at the back of the machine.  

NZ Transport Agency Waka Kotahi Project Manager Caleb Perry says having the road header onsite is exciting for the project.

“We’ll start to see some progress with the road header excavating up to three metres every day.

“The tunnel will be cut in two stages, with the upper portion (top heading) first, followed by the bottom section (bench). At regular intervals, excavation will be paused and ‘shotcrete’ – a sprayed-on concrete – will be applied to the crown and walls to line and support the structure.

“The design and construction of the tunnel are similar to the Northern Gateway Tunnel in Auckland and the tunnel will be large enough to accommodate loads up to and including house removals – this isn’t something that can currently be accommodated on the steep, narrow winding stretch of SH3.”

At this stage, the excavation is expected to be completed later this year.

“The Mt Messenger Bypass will make this stretch of SH3 much more resilient, and safer for all motorists, providing a secure connection through North Taranaki, especially for freight,”  Perry says.

The project involves building a 6km section of new highway to the east of the existing Mt Messenger route which includes the tunnel and two new bridges. Completion is expected in late 2026 or early 2027.