Stormwater works

Other improvements for the route

Passing opportunities

Median barriers

What safety improvements are you making to this stretch of SH3?

Safety improvements we are making on this stretch of SH3 include roundabouts at the intersections of Princess Street, Waitara Road, State Highway 3A/Mountain Road, and De Havilland Drive, sections of median barrier, bridge widening, and other intersection improvements.

Construction on the Princess Street roundabout and pedestrian and cyclist underpass began in March 2023.

How will this project make the route safer?

The project will help prevent deaths and serious injuries on the route.

The roundabouts will provide safer access on and off the highway for motorists and median barrier will help prevent head on crashes.

When will construction of the roundabouts begin?

Construction of the SH3 Princess Street roundabout and pedestrian and cyclist underpass began in March 2023 and is due to be complete by mid-2024.

Construction of the SH3 Waitara Road roundabout is due to begin in early 2024.

When will the project be completed?

We expect to construct the roundabouts over four years, with construction of the last roundabout expected to begin in 2025.

This timeline is dependent on a variety of factors, including land acquisition, consents, weather, and ground conditions.

How much will the project cost?  

The project is expected to cost around $82 million to deliver.  This funding has already been secured from the National Land Transport Programme (NLTP) and Crown funding. 

Will the safety improvements support the current and future residential growth in the area?

The roundabouts will support development by making access to local communities safer.

Why did you refine the roundabout concepts?

After carrying out investigations and preliminary designs for the roundabout concepts from the business cases developed in 2018, we identified that they would take a number of years to progress to construction due to the significant land and stormwater requirements and associated costs.

We refined the concepts to reduce land and stormwater requirements and cost to speed up construction.

How different are the refined roundabouts concepts from the ones in in the business cases?

The concepts are not too different from those identified through the business case process and will provide the same safety and access benefits as the concepts developed in 2018. We have slightly shifted their orientation and slightly reduced the size of the roundabouts, but they all meet current design standards.

Why are the De Havilland/Airport Drive and SH3A (Mountain Road) roundabouts two laned and the Princess Street and Waitara Road roundabouts single laned?

The number of lanes was determined during the business case stage. Comprehensive traffic modelling for the De Havilland and SH3A (Mountain Road) roundabouts determined two lane roundabouts were required. Single lane roundabouts were found to be adequate for Waitara Road and Princess Street intersections.

With increasing traffic volumes and residential development planned for the area, will these safety improvements still be fit for purpose in five years’ time?

Yes. The roundabouts are designed to cater for expected traffic growth over the next 25 years.

Stormwater works

How much stormwater goes to the Manukorihi Park wetland treatment swale?

The treatment swale treats road run-off from the new roundabout. The volume of run-off is equivalent to a third of the 2-year rainfall event.

What happens to runoff in larger events?

The initial runoff will enter the treatment swale and be treated. The rest of the runoff will continue along the large stormwater pipe to the new Waitara Awa (River) outfall. This will ensure the swale and stream are not overwhelmed by additional run-off. The large stormwater pipe is also designed to take run-off from upstream of Rahiri Street to alleviate existing flooding issues.  

Will contaminants end up in the rivers?

The treatment swale will receive and treat run-off from the smaller regular rainfall events and the initial run-off from larger rainfall events. This is in accordance with current best practice and will capture most of the contaminants off the road. It provides a significant enhancement to water quality entering watercourses.   

How will all the extra run-off affect the Awa (rivers and streams)?

The wetland swale and outlets to the Awa (stream) in Manukorihi Park is designed to limit the flows to a level which will not adversely impact the stream and stream ecology.

The larger stormwater flows (volumes) entering the Waitara Awa (river) will not impact the river as they are small compared to overall river flows. The outlet to the river will be designed with rock protection works to ensure that there is no erosion to the riverbank.   

What will happen to stormwater run-off from the Waitara Road roundabout?

Currently, stormwater run-off from the Waitara Road intersection flows into a watercourse that discharges into the Waiongana Awa.

During construction of the Waitara Road roundabout, we will build a stormwater treatment swale at Raleigh Street. Water from the roundabout will flow into the swale for treatment before being discharged into the watercourse that flows into the Waiongana Awa.

Other improvements for the route

What other intersection safety improvements will you be making on the route?

Right turn movements at intersections are over-represented in the crashes.  As part of the project, we will install median barrier which will limit right turns at Mamaku Road, Richmond Road, Mahoetahi Road and Old Devon Road.

What about Wills Road and Corbert Road intersections?

Waka Kotahi is aware of the safety issues at these intersections and is working with New Plymouth District Council to identify safety solutions for the intersections as part of this project.  

Are there any other safety improvements for cyclists and pedestrians?

The project’s main objective is to improve safety through intersection improvements and median barrier, and we are proposing changes that will improve safety for people who walk and bike in the area.

All roundabouts will include alternative cycle paths around the outside providing a safe way for cyclists to navigate through. We are also widening some sections of roadside shoulder to improve safety for cyclists.   

We are also building an underpass at Princess Street to provide safe access for pedestrians and cyclists across the highway.

In addition, the coastal shared path extension from Bell Block to Waitara is scheduled to be completed in 2027, providing a safe off-road commuter route for cyclists and pedestrians for those who might otherwise use SH3.

Will the speed limit be put back up to 100km/h between Waitara and Bell Block once the infrastructure improvements are made?

We are not proposing to reinstate the 100km/h speed limit after the completion of the works.  The safety improvements have been designed to fit the new 80km/h speed environment which also provides an overall safer state highway corridor.

Will the weigh station at SH3A (Mountain Road) be relocated?  

Yes. The weigh station is an important facility that allows NZ Police to enforce heavy vehicle safety standards. We are in the process of identifying another suitable site for the weigh station.

Will the existing Airport Drive intersection be closed?

The current intersection of Airport Drive with SH3 will be permanently closed and realigned to form a four-way roundabout with De Havilland Drive. The closed end of Airport Drive will become a cul-de-sac and will be accessed from the realigned section of Airport Drive.

What happens to Raleigh and Tate roads?

The intersection of Raleigh and Tate roads will be changed, so the main flow of traffic is from the new roundabout onto Raleigh Street towards Waitara. Access to properties at this intersection will be maintained, as will access to Tate Road north of the intersection.

Will you be closing the SH3/Nelson Street intersection?

We are currently developing a plan for the installation of stretches of flexible median barrier along SH3. At this stage, there are no plans to close the intersection with Nelson Street.

Passing opportunities

Why have you removed the passing lanes on this stretch?

With the increasing number of vehicles using the road, the passing lanes were becoming unsafe and having very little benefit to travel times.

Removing the passing lanes allows us to create wider shoulders and a wide centreline. This will help reduce the risk of head-on crashes and provide space for median barrier to be installed once the roundabouts are built.

Will you be providing safe places for motorists to pass agricultural vehicles as part of the project?

We are aware that this is a concern for some motorists. We are investigating opportunities such as stopping bays for agricultural vehicles as part of the design process. Additional lanes on the exits of the roundabouts and accessways will also provide opportunities for agricultural vehicles to pull over for other vehicles to pass.

Will agricultural or over-dimensional vehicles still be able to use the road?

Yes. All our proposed changes cater for all vehicles. The roundabouts cater for over-dimensional vehicles. Over-dimensional vehicles will be able to lift their loads above the median barrier height to travel.

Median barriers

Why are you installing median barrier? 

Many of the crashes on SH3 between Waitara and Bell Block are head-on or at intersections so the combination of median barrier and roundabouts will significantly reduce the risk of these types of crashes. Median barriers are a cost-effective infrastructure treatment that can reduce the number of people killed or seriously injured in crashes by 65 percent.

Are you installing a median barrier along the whole project route?

Flexible median barrier will be installed in sections.

The designs for the first two sections of flexible median barrier have been confirmed. These designs were finalised following engagement with landowners and businesses along the route, emergency services, and representatives from the freight industry.

The first section of median barrier will start approximately 300m west of the intersection of SH3 and Bayly Street and end approximately 40m east of the Mamaku Road intersection. We are aiming to have this section installed or under construction by mid-2024. This section of median barrier will not impact on access to properties or side roads.

The second section of median barrier will start approximately 40m west of the Nelson Street intersection and will end at the future Waitara Road roundabout. This will be installed once construction on the Waitara Road roundabout is complete. People driving on the road who need to turnaround will be able to use the Princess Street Roundabout or the Waitara Road roundabout.

The plan and timeline for installation of median barrier at the Mamaku Road and Nelson Street intersections, as well as along the rest of the route, is currently being confirmed.

Will the median barrier affect access to my property?

We have engaged with property owners along the route where the first two sections of median barrier will be installed.

We will engage with property owners along the rest of the route who may be impacted by the median barrier before it is installed.

Will having a median barrier mean I have to travel further?

Where a flexible median barrier is installed, those entering the highway from a private access or side road will only be able to turn left, and they will need to use a safe turnaround area or roundabout to go in the opposite direction.

People who need to turn left out of their driveways will be able to use a roundabout or other safe turnaround facility to turnaround.

This would only add a few minutes to journey times but significantly increase safety for everyone using the route.

To achieve the greatest safety benefit for the flexible median safety barrier, there will be as few gaps in the barrier as possible.

How will emergency services get to people in an accident if a flexible median barrier is installed?

Flexible median barriers can be lowered and driven over in emergency situations if needed. Flexible road safety barriers significantly reduce the number of crashes on roads where they are installed. When developing designs, we work closely with the teams who manage incidents on the road.

Are flexible median barriers safe for motorcyclists?

It’s no secret that people on motorcycles have a higher risk of getting seriously hurt or even killed on our roads. They are more exposed and our roads and roadsides can be unforgiving.

Barriers, especially flexible median barriers, can reduce the number of motorcyclists killed and injured on our roads by 50 percent.*

Barriers between lanes stop a driver’s mistake from becoming a rider’s nightmare. They can also stop riders ending up in the path of oncoming traffic if they come off their motorcycle.

*Carlsson, A. (2009). Evaluation of 2+1 roads with cable barrier. Final report. VTI rapport 636A.

Will the flexible median barrier make the road narrower?

No, there will still be enough room for all vehicles.

I just don’t like the idea of a flexible median barrier on this road.

We understand that not everyone likes the idea of flexible median barrier down the middle of the road. Proposals like this aren’t always popular but keeping people alive on our roads is our number-one priority. Along with the median barrier, we are building new roundabouts so people can change direction safely and easily with just a few extra minutes’ drive time. We think this small inconvenience is worth it, as it could save the life of someone you know and love.

Last updated 31 August 2023