FAQs

This page contains frequently asked questions (FAQs) and answers about Te Aranui o Te Rangihaeata – the Transmission Gully motorway project.

About the project

What is the Transmission Gully motorway?

The Transmission Gully motorway is a 27-kilometre four-lane motorway north of Wellington that forms part of State Highway 1. It provides important regional resilience and a safe, modern, reliable route to and from Wellington. The motorway has been open to the public since March 2022, however some related construction works are yet to be completed.

It was also New Zealand’s first transport infrastructure project to be delivered under a Public Private Partnership (PPP).

Who was responsible for the construction of the Transmission Gully motorway?

Wellington Gateway Partnership (WGP) is the contractor delivering the PPP project for the NZ Transport Agency. CPB Contractors and HEB Construction Joint Venture (CPB HEB JV) has been sub-contracted by WGP to design and build the project.

Where did the names for the motorway come from?

The name Transmission Gully comes from the 110,000-volt transmission line that used to run through it.

Te Aranui o Te Rangihaeata refers to the route to Kāpiti taken by the great Ngāti Toa Chief Te Rangihaeata, after his stand against Crown forces at Battle Hill. This name was gifted by Ngāti Toa iwi.

What are the key benefits of the Transmission Gully motorway?

Transmission Gully provides:

A safer road with central median barriers, a four-lane route and additional crawler lanes on the steeper sections.
Better resilience to landslides, floods and damage to the motorway from a major storm or earthquake.
Quicker reinstatement than the alternative State Highway 59 (former SH1) in the event of a major earthquake.
Peak period travel time savings estimated at around 10 minutes per vehicle for Kāpiti to/from Wellington, 15 minutes Kāpiti to/from the Hutt Valley and five to seven minutes quicker from Porirua to/from the Hutt Valley.
Improved access from State Highway 1 to Porirua and the Hutt Valley with shorter and more efficient freight movements to and from Seaview/Gracefield, Wingate and the Wairarapa.
Important arterial connections for residential and light commercial areas in eastern Porirua to the State Highway network through two new link roads.
An alternative strategic link for the Wellington region, which has improved regional road network security.

Where does the Transmission Gully motorway start and finish?

Transmission Gully is an important part of State Highway 1 and the Wellington Northern Corridor. The 27km long motorway connects the Kāpiti Expressway at Mackays Crossing in the north with the Porirua-Johnsonville Motorway near Kenepuru in the south.

It features five interchanges at Mackays Crossing, Paekākāriki, SH58 near Pāuatahanui, Waitangirua and Kenepuru.

If you are unfamiliar with Transmission Gully, make sure you plan your journey and check out our website.

How to drive Transmission Gully

How do get on to Transmission Gully from the north (eg from Kāpiti)?

State Highway 1 connects directly to the Transmission Gully motorway just north of the Mackays Crossing Interchange.

If you’re travelling south from Kāpiti, and don’t want to continue on the Transmission Gully motorway, you’ll need to exit at either the Mackays Crossing or Paekākāriki interchanges. This will connect you with State Highway 59. This is the best route if your destination is Wellington.

Note: If you miss the southbound exit at Paekākāriki, the next opportunity to turn off the motorway is 15kilometres away, at the State Highway 58 Interchange at Pāuatahanui.

How do I get on to the Transmission Gully motorway from the south (eg from Wellington)?

State Highway 1 connects directly to the Transmission Gully motorway, south of Porirua near Kenepuru. As you approach the Kenepuru Interchange, stay in the left lanes to continue on SH1 via the Transmission Gully motorway. This is the best route if you are travelling to Whitby, Waitangirua, Pāuatahanui, Hutt Valley (via State Highway 58) or Kāpiti.

If you’re travelling to Porirua or further on towards Paremata or Plimmerton, you’ll need to be in the right lanes to continue on State Highway 59.

How long is the motorway?

Transmission Gully is 27 kilometres long and takes about approximately 18 minutes to drive.

What is the speed limit on the Transmission Gully motorway?

The speed limit on the Transmission Gully motorway is currently 100km/h.

Will the speed limit on the Transmission Gully motorway be increased to 110km/h?

While some motorways/expressways in NZ have sections with a 110km/h speed limit, this has yet to be considered for the Transmission Gully motorway and a speed management review cannot start until remaining project works are finished.

Delivery

Why did construction of the Transmission Gully motorway take so long?

The Transmission Gully motorway is one of the more significant and complex roading projects in New Zealand. Spanning 27 kilometres of geologically and geotechnically challenging and steep terrain, the project required innovative environmental and construction techniques, with 25 major structures including the largest bridge, Te Ara a Toa, which is 230 metres long and 60 metres high.

Cuts of up to 70 metres were also made through Pouāwhā - the Wainui Saddle, where the Ohariu fault line crosses the motorway. The saddle was lowered to a final crest height of 253 metres above sea level.

Overall, more than 11 million cubic metres of earth was moved during construction of this motorway.

The project was also impacted by COVID 19 and the associated Alert Level 4 lockdowns.

What work is left to do?

Remaining work includes final surfacing of the SH59 connection between Mackays Crossing and Paekākāriki, minor work at Pāuatahanui adjacent to the SH58 interchange, recreational tracks along parts of the route, maintenance access tracks, and completing the required consenting requirements, quality assurance and works completion tests.

What work is currently being done?

The project was constructed in stages to allow the early opening of the motorway to the public, whilst allowing work on the wider state highway network that otherwise would have caused significant disruptions for motorists without an alternative route.

A specific date for completion of the outstanding works is not yet set. A programme of work is currently underway to finish the remaining works.

Please see the current works page for more information.

Current planned works

When will the Transmission Gully motorway be completed?

No specific timeframe for project completion can be given at this stage. While the parties continue to work towards the end of construction, it should be noted that the motorway continues to provide good, safe service and important regional resilience.

Is the Transmission Gully motorway safe to drive if it isn’t fully completed?

Yes. The Transmission Gully motorway has been open to the public since March 2022 and continues to provide good, safe service and important regional resilience.

The NZ Transport Agency continues to work closely with both Ventia (the road operator) and WGP to ensure the highway is maintained and kept safe for road users.

Public Private Partnership

What is a PPP Project?

The Transmission Gully motorway was the first motorway in New Zealand to be constructed on behalf of the New Zealand Government under a Public Private Partnership (PPP) contract.

A PPP is a long-term contract between the public and private sectors covering the financing, construction, maintenance and operation of public infrastructure and services. The motorway remains a public asset – it is not owned by the PPP.

PPPs allow large and complex projects to benefit from private sector innovation, and risk management and financing which can increase certainty of delivery and drive better value-for-money.

Development of the Transmission Gully motorway PPP

What is the estimated project cost?

The estimated project cost is $1.25 billion. As an integral part of the Public-Private Partnership (PPP) is to build and operate Transmission Gully motorway, the cost of maintaining the motorway is included within the contract price and therefore there are no additional maintenance and operation cost to the government/taxpayers.

Who is the motorway operator and what is their role?

Ventia’s current role is to manage the 24/7 operation of the motorway, which includes providing corridor and traffic management, incident response, and some maintenance (eg median barrier repairs, etc.). Because construction elements of the project remain incomplete, Ventia’s role has commenced but not in full.

Ventia works closely with the road builder (CBP HEB JV) to manage planned works in a safe manner that minimises disruption for travellers, as well as working alongside the Wellington Transport Alliance and Wellington Transport Operations Centre (WTOC).

Management of serious crashes will always involve emergency services.

You can read more about Ventia’s role on our website.

Operation and maintenance page

Who looks after the surrounding environment and vegetation?

While the Transmission Gully motorway project remains in the construction phase the relevant environmental obligations remain with the road builder (CPB HEB JV). Operational environmental compliance will pass to Ventia once the motorway construction is complete.

Safety

How can I plan my journey?

To plan your journey and stay informed, please check the NZ Transport Agency’s Journey Planner.

Journey Planner(external link)

Can I walk or cycle on Transmission Gully?

No. Because the Transmission Gully is a motorway, walking and cycling is prohibited. All southbound on-road cyclists must take the off-ramp at Mackays Crossing to continue on SH59.

The safest route for people walking and on bikes is via the Te Ara o Whareroa shared path through Queen Elizabeth Park, which connects with the Kāpiti cycle route and further south via SH59 to the Te Ara Harakeke shared path.

Walking and cycling

What should I do if I miss my exit?

If you miss your exit, don't stop and reverse – drive on to the next exit instead. If you are unfamiliar with the Transmission Gully motorway, make sure you plan your journey before setting off and check out our website.

How to drive Transmission Gully

Please remember to:

drive to the speed limit (remember, the faster you go, the more likely you are to be killed or seriously injured if you crash).
merge like a zip when joining the motorway.
drive to the conditions and turn your headlights on if visibility is poor.
pay attention to any VMS signs, which may advise of incidents ahead or advice for drivers.
do not stop on the motorway unless it is an emergency.
drive without distractions (eg do not use your phone while driving).

What weather conditions can I expect when driving?

Parts of the motorway are located high in the hills and can be affected by strong winds, fog, among other elements. It’s important that you drive to the conditions and adjust your speed and driving accordingly – this includes increasing your following distance.

The variable messaging signs will warn you if there is low visibility, high winds, or other hazards and remind you if the conditions require reduced speed.

What happens if an accident closes the road?

If a crash or other incident, such as a car fire, medical event or severe weather, happens, the motorway may need to be closed to allow emergency services to respond. Variable message signs will be used to advise of incidents ahead and/or advice for drivers, and a detour may also be put in place.

You can also follow the NZ Transport Agency on Facebook (external link)or Twitter(external link) for the latest traffic.

In the event of a major crash or incident, emergency services manage the response and complete their investigations; Ventia co-ordinates the clean-up, repairs to barriers, etc, and under guidance from WGP, NZ Transport Agency or emergency services will reopen the road.

What should I do if my vehicle breaks down or I have an accident?

The Transmission Gully motorway uses an Intelligent Transport Systems (ITS) to provide accurate, real-time incident detection and prompt response, as well as the collection of travel data.
The ITS detects changes in the traffic flow using radars along the motorway.

Ventia then directs their on-road Incident Response Service (IRS) team to where it is needed on the motorway, whether it’s for a breakdown or other incident.

Please call 0800 TG INFO to report someone that is broken down or stopped on the motorway. If an emergency, call 111 first.

Is there mobile phone coverage?

As with many roads through rural areas, there have been sections of the Transmission Gully motorway where road users experienced issues with mobile phone coverage. These sections vary by mobile provider.

New cell phone towers have been installed by the Rural Connectivity Group (RCG).Regardless of any coverage issues experienced, in an emergency, all cell phone providers reroute 111 calls to the nearest available mobile network.

Are there any service centres or fuel stations along the Transmission Gully motorway?

There are no service centres along the Transmission Gully motorway.

We advise motorists to use SH59 if they are low on charge/fuel.

You can plan your journey using the NZ Transport Agency Journey Planner.