New Zealand-based transport agency NZ Transport Agency Waka Kotahi (NZTA) has started tunnelling work at the Te Ara o Te Ata – Mt Messenger Bypass project in North Taranaki, New Zealand.
The Mt Messenger Bypass involves building a new section of State Highway 3 to bypass the steep, narrow, and winding Mt Messenger area, which is prone to natural hazards.
The project is expected to improve road safety, resilience, and journey experience.
The new 6km route, from Uruti to Ahititi, bypasses the Mt Messenger section of State Highway 3.
The project includes two bridges, one 125m and another 30m long, plus a 235m tunnel. The new route will be lower and less steep, enhancing travel.
The first cut was made by a 110-tonne road header machine to excavate a 235m tunnel as part of the Bypass project.
NZ Transport Agency said road headers are perfect for various geological conditions, with boom-mounted telescopic cutting heads.
The road header has a shovel plate at the front to collect excavated rock and soil, which is then transported via a belt to dump trucks at the rear.
The 235m tunnel is a key component of the Bypass project, enhancing the resilience of State Highway 3, the transport agency said.
NZTA project manager Caleb Perry said: “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.”
Excavation is expected to be completed by the end of this year.
