Manawatū Gorge replacement highway takes shape
Friday, 26 February 2021
Across the river from the mothballed highway through the Manawatū Gorge, construction is rumbling into action for a replacement road. Jimmy Ellingham reports.
Huge earthworks are changing the face of the Ruahine Range’s southern peaks, home to a much-anticipated four-lane road connecting the eastern and western sides of the lower North Island.
Construction of Te Ahu a Turanga Manawatū Tararua Highway began in January and it is scheduled to open in December 2024.
Until then the road will take shape, ready to be covered in tarmac for the 6000 vehicles a day now using the windy Saddle Rd when travelling between Manawatū and Hawke’s Bay.
It’s estimated the new road will take about 13 minutes to drive.
**READ MORE:
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* Manawatū Gorge replacement highway decision expected soon; preparation work starts
* New clip-on to give Ashhurst Bridge walkers and cyclists safe passage
**
Among the work sites is a gully near the Ashhurst end of the $620 million project.
Stuff was this week granted access to the area, where huge machines were scraping massive piles of soil down a steep gradient to fill the gully – “fill 9” as it’s known.
It will transform into a sweeping upward curve heading towards the wind turbines and will be the steepest part of the new 11½ kilometre road.
“This bit of earthworks will be ongoing for the next three years,” said Waka Kotahi NZ Transport Agency project spokesman Lonnie Dalzell.
The construction alliance’s project engineer for this section of work, zone 2, Dane Gray, said of the four scrapers smoothing the area into a highway this week, two were working nonstop, while two were operating when needed.
“One of these machines can do roughly 1500 [cubic metres] a day.”
It’s a lot of material, but a drop in the bucket overall. Dalzell said about 300,000 cubic metres of material would be moved this year, rising to 2½m a year in 2022 and 2023.
“The work we’re doing here is ramping us up for those big years.”
Work is happening six days a week, with plans to move to seven and the possibility of introducing two shifts a day.
Dalzell said it was estimated earthworks could happen 109 days a year.
Gray said scraping work on a steep slope wouldn’t be possible in muddy conditions.
Motorists from the Ashhurst end will arrive at the up-hill section after crossing two bridges, one over the Manawatū River and one over sensitive wetland. Each bridge will be more than 300 metres long.
Bridge work is expected to start within weeks and the progress will be easy to follow from a viewing platform at the car park created for gorge walk users.
The new park is at the entrance to the old State Highway 3, which closed in April 2017 when a slip fell on to the road. Concerns about the stability of the hillside shut the route indefinitely.
The replacement highway includes a shared cycling and pedestrian path, and there are plans to create other walkways, including one overlooking the rise near Ashhurst. It would start off the Saddle Rd on what is now a bumpy gravel site access track.
As well as building tarmac, 46 hectares of native forest will be planted and pest control measures introduced.
Also visible around the construction sites are ponds. They’re dry at the moment, but when it rains water running off the earthworks will flow in to be treated before heading into the area’s waterways.
About 100 people from the alliance are working on the site. That is expected to rise to about 350 a day at the project’s peak.
An Environment Court decision in 2020 gave the new road its final green light, and “enabling works”, such as the access road to the Ashhurst rise site, began shortly after.
By the numbers
Six million cubic metres of earthworks.
New embankments up to 28 metres high.
About 2 million plants will take root as a result of the project.