Bid for 120kph speed limit on Christchurch Southern Motorway

Wednesday, 14 August 2024

Christchurch Southern Motorway could see its speed limit increase to 120kph. (File photo)

Drivers could be cruising down the Christchurch Southern Motorway at 120kph if Selwyn’s mayor gets his way.

The coalition government is reviewing speed limits across the country as it reverses the blanket reductions made by the previous Labour Government in 2022.

Under the draft Setting of Speed Limits Rule 2024, released for consultation in June, Transport Minister Simeon Brown asked for feedback on highways that could be increased to 120kph.

Selwyn District Council mayor Sam Broughton wrote to the Ministry of Transport, Brown and Act Party leader David Seymour in July in support of the idea.

Increasing the speed between Rolleston and Christchurch to 120kph from 100kph would be appropriate because many drivers were already speeding, he said.

“Whether it is for general traffic, direct public transport services, or moving freight, council considers increasing the speed limit of the motorway between Rolleston and Brougham St will assist in improving efficiency and connectivity while still being safe,” he wrote.

“This is reflected in generally higher average speeds above 100kph we already observe along the motorway.”

Luxon and Transport Minister Simeon Brown released the Government's plans for the sector.

Transport expert Professor Simon Kingham said raising the speed limit meant spending large sums of money to build a suitable road, just to save a few minutes of travel time.

“If we as a region want to engineer the road to be able to go faster we have to spend money to do that.

“It’s going to be a handful of seconds of minutes, but at what cost.”

If the speed increased, so would the crashes and their severity, Kingham said.

There are no roads in Aotearoa that can safely be driven on at 120kph, an NZ Transport Agency Waka Kotahi (NZTA) spokesperson said.

Selwyn’s mayor Sam Broughton supports speed increases on two sections of highway across his district. (FIle photo)

The fastest motorways currently are the 110kph Waikato Expressway and the Tauranga Eastern Link.

A proposal to increase the Christchurch Southern Motorway to 110kph was being developed by the Government, the spokesperson said.

Since opening in 2020, five people had been seriously injured in crashes on the motorway, according to NZTA statistics. None were fatal.

But it expected more vehicles on the highway in the next decade. In 2021, 21,000 vehicles used the motorway daily. This was expected to jump to 33,000 by 2040.

Transport expert professor Simon Kingham says building a road to support 120kph driving safely will be expensive. (File photo)

Broughton said Rolleston’s population would increase by 20,000 people to become a city of 50,000 by 2050. The Selwyn district’s total population is expected to rise from 86,000 to more than 190,000 in the next 10 years.

In his letter to Brown, Broughton also said he supported reverting the speed limit on a section of State Highway 75 between Halswell and Akaroa to 100kph.

The highway from Halswell to Little River was reduced to 80kph in 2022 to improve safety. The section from Little River to Akaroa was reduced to 70kph and 60kph in areas. Some other sections, such as school zones, were reduced further.

Charlotte Armstrong, 28, died after her 4WD slid on black ice and crashed into a school bus on State Highway 75 between Halswell and Little River in 2015. (File photo)

There were 747 crashes from Halswell to Akaroa from 2011 to 2020, according to NZTA statistics. Nine people died and 74 were seriously injured.

NZTA recorded 24 crashes from Halswell to Little River, six from Little River to Akaroa, and no deaths between the reductions came into effect and May 2024.

The speed reductions had sparked intense debate from road users. Some said crashes were due to poor driving, while others said speed reductions were essential to protect lives.

Broughton said NZTA did not produce any “compelling evidence” to reduce the speed limit from Halswell to Little River. The change made travel less efficient, frustrated motorists, and led to risky behaviour due to long queues, he said.

“This rural section is flat and easy to drive, with long straights that do not warrant such an onerous blanket speed restrictions.”

The council want to keep the 60kph speed limit from Little River to Akaroa and requested Tai Tapu remain at 50kph, Broughton said.

National’s Banks Peninsula MP, Vanessa Weenink, said NZTA would have to apply for exemptions, otherwise the speed changes on SH75 would be reversed by July 1, 2025.