Why you can’t drive 110km/h on Transmission Gully

ANALYSIS

Transmission Gully was designed to be safely driven at 110km/h but 16 months after the highway north of Wellington opened, motorists are still not legally allowed to travel at this speed.

The 110km/h speed limit is being considered on the Peka Peka to Ōtaki expressway, which opened several months after Transmission Gully, as well as on the Mackays to Peka Peka motorway.

So, why not on Transmission Gully too?

Waka Kotahi New Zealand Transport Agency says it’s because the $1.25b road isn’t technically finished yet. In fact, the parties in the Public Private Partnership (PPP) are still wrangling over the fallout of the 2021 Delta outbreak that sent the country into lockdown.

It’s easy to forget this considering people have been happily driving on the road for some time now.

The road was only able to open in March last year after Waka Kotahi New Zealand Transport Agency agreed to defer some quality assurance tests until after the opening and reduced the requirements for others.

Last month the Herald reported outstanding works included the new State Highway 59 connection between Mackays Crossing and Paekākāriki as well as works at and adjacent to the Pāuatahanui interchange.

A recreational track along parts of the route needed completing, as well as maintenance access tracks, various off-road work, required quality assurance tests, and consenting tasks.

Transmission Gully. Photo / Mark Mitchell

The new higher speed limit of 110km/h can only be considered for roads designed and constructed to the necessary standards and only after comprehensive review and consultation.

Waka Kotahi has to examine whether it is appropriate to increase the speed limit without compromising driver safety.

There are two roads in New Zealand that have 110km/h speed limits- the State Highway 2 Tauranga Eastern Link Toll Road and State Highway 1 Cambridge section of the Waikato Expressway.

Together Transmission Gully, Mackays to Peka Peka, and Peka Peka to Ōtaki form a new section of State Highway 1 out of Wellington.

Between 2008 and 2022 there were more than one thousand crashes on the old highway route. Of these, 10 were fatal, and 55 were serious.

Since Mackays to Peka Peka opened in 2017, the number of incidents has fallen dramatically to 166 crashes. None of these were fatal and only seven were serious.

There have been four minor crashes since the Peka Peka to Ōtaki section opened late last year.

Early indications are that Transmission Gully crash numbers reflect the same improvement in safety, but Waka Kotahi says its speed management review cannot start until the remaining project works are finished.

So, what’s the holdup?

Last month Wellington Gateway Partnership chief executive John Humphrey said final completion has been slower than anticipated.

“We are advised by the road builder that there are a number of reasons for this. Their work programme relies substantially on local workforce and they have had to compete in a very competitive market for the necessary skills, resources and materials.”

Humphrey said it also took more time to complete works now Transmission Gully was open to traffic.

“The builder’s schedule has been careful to minimise traffic disruption which includes efforts to align the timing and location of their works with Waka Kotahi project works in the vicinity.”

The final cost of the road remains unknown as project partners continue “ongoing discussions” about compensation for Covid-19 delays.

The road was originally thought to cost $850m to build and was last estimated to cost $1.25 billion.

Georgina Campbell is a Wellington-based reporter who has a particular interest in local government, transport, and seismic issues. She joined the Herald in 2019 after working as a broadcast journalist.