Manawatū and Tararua highway: numbers don't add up, mayor says

A key number in determining if a lower North Island highway is suitable for tolls is under question.

Public consultation is open on plans to impose a charge on motorists using the new highway between Manawatū and Tararua, expected to open mid next year.

The plan to charge motorists $4.30 and trucks $8.60 a trip has come under heavy criticism from people in surrounding areas, who have waited years for the new highway to open.

The NZ Transport Agency has released its tolling assessment for the new road under the Official Information Act. It includes a section on compliance under "legislative requirements and practicality test".

One of these requires that, for a road under consideration for tolling, "not less than 10,000 vehicles are likely to travel the road per day".

Transport agency modelling forecasts 10,902 vehicles a day using the road in 2025, rising to 14,250 a day in in 2048.

But the figure of 10,902 requires a huge increase from the traffic counts available and Tararua District mayor Tracey Collis says the transport agency's number don't add up.

When the old State Highway 3 through the Manawatū Gorge closed in 2017 due to rockfall, it carried 7600 vehicles, including 1100 trucks a day.

A traffic count provided to RNZ from 2019 showed 5565 vehicles used the alternative Saddle Road on a particular day, and 1944 used fellow alternative the Pahīatua Track. Of those 7509 vehicles, about 11 to 12 percent were trucks.

And 2023 figures showed 6000 vehicles a day on the Saddle Road, which included many construction vehicles for the new road.

The 10,902 figure is a 43 percent increase on 2017 traffic volumes and Collis has cast doubt on it.

"The vehicle numbers do not stack up from previous use and do not reflect real data. They have been made up to match a tolling policy so they could get it over the line with a minimum of 10,000 vehicles needed," she said.

"To imagine 11,000 vehicles would equate to 458 vehicles per hour or 7.6 per minute. Anyone who has travelled our roads will have an image of how unrealistic those numbers are."

Labour transport spokesman and Palmerston North MP Tangi Utikere also said the 10,902 estimate was questionable.

"Where's the data they've used to base these figures on?"

"One of the concerns is it's certainly not fair to be releasing this information midway through a process," he said of the public consultation on the proposed toll, which closes on 7 October.

"People could have already made a submission and not been aware of potential issues with the figures."

The other three criteria the road satisfied, according to the assessment, were that it's a new route or a significant upgrade, that there's a "feasible free alternative", and that tolling infrastructure can be installed in a cost-effective way.

Under the requirement that at least 10,000 vehicles a day use the road, the assessment said: "This is a test that may be indicative of the likely viability of the toll road, but may be taken into consideration with other criteria."

Collis said the road wasn't new. It was a replacement for the old state highway, which shut. She also called into question that the alternative routes were feasible, saying they weren't safe or built for high traffic volumes.

A transport agency spokesperson said the estimate for the new road's modelling began by taking into account 2016 volumes on the Manawatū gorge road, Saddle Road and Pahīatua Track.

"Annual traffic growth of 3 percent is then added to this figure to provide a projected traffic count for Te Ahu a Turanga: Manawatu Tararua Highway when it opens in 2025.

"Growth rates from various sites including SH54, SH3, SH2, were considered when determining the rate for Te Ahu a Turanga."