SH1 Tīrau to Waiouru accelerated maintenance project update

SH1 Desert Road is open!

14 March 2025

In this week's issue:

• SH1 Desert Road is open!
• Taupō to Tūrangi update
• We don’t want to see your crack
• Putāruru to Lichfield: Digging deep to create a smooth ride
• Ātiamuri to Wairakei: Busy times
• Introducing some of the T2W crew
• Fabric sealing: A good underlay
• Great barriers: Clever engineering to keep you safe
• Road worker of the week

Current closures

2 closures between Tīrau and Taupō:

• SH1 Putāruru to Lichfield closed for approximately 3 weeks (weather dependent). Detour adds approximately 16 minutes and 18.5km to journeys.
• SH1 Ātiamuri to Wairakei closed for approximately 4 weeks (weather dependent). Detour adds approximately 23 minutes and 32km to journeys.

Video of SH1 Desert Road works ahead of opening.

SH1 Desert Road is open!

The day you’ve all been waiting for is here. SH1 Desert Road is open! On time and we even did a little more work than we promised. 

In just over 8 weeks we have rebuilt and repaired 28 lane kilometres of road, 12 lane kms more than we originally planned, and completely rebuilt the deck of the Mangatoetoenui Bridge, located 23km south of Rangipō.

Doing the work under closure has meant we were able to bring this section of SH1 up to a higher standard, quickly. 

It’s been a massive job. Thank you to everyone who has worked with us and used the official detours while we’ve had the road closed. We have also had people say how they have enjoyed the beautiful countryside the detour has taken them through. The Ruapehu District has also enjoyed a much-needed business boom, especially Ohakune.

Parts of SH1 are still under traffic management with temporary speed limits for the next few days to let the chipseal bed in properly. Please keep to the speed limits. Speeding could cause damage to your vehicle and the new surface. There will also be an increased presence from NZ Police in the area to help enforce the speed limits.

We will be returning at a later stage to complete the final surface. This work, where possible, will be done at night and under stop/go traffic management.

The scheduling is still being worked through for when this final surfacing will be done.

Rebuilding of the Mangatoetoenui Bridge, SH1 Desert Road.

Total work across all sections of T2W since Sept 2024:

• Lane kms completed: 86.78 lane kms (480,926m2)
• Foam bitumen stabilising completed: 51 lane kms (270,102m2) 
• Re-seals completed: 31 lane kms (162,514m2) - includes chipseal and asphalt concrete surfacing
• Structural asphalt concrete: 4.78 lane kms (26,837m2)
• Tonnes of metal used: Approximately 162,609 
• Truckloads of metal: Up to 145 loads per site per day
• Number of workforce hours to date (road crews): Approximately 85,000
• Number of lost-time injuries: Zero
• Number of contracting firms working across sites: Up to 32 working at once.

Taupō to Tūrangi update

We have made the decision that a full closure would not be the best option for this part of SH1 due to the issues it would cause for the community, freight and businesses.

We have received considerable feedback about the proposal to close SH1 between Taupō and Tūrangi in October and November. 

We do have considerable maintenance to do on this stretch of SH1, including some bridge strengthening work, so there will still be disruptions. We will spend some time investigating the best options for getting this work done. These options could include stop/go, having 1 lane open and nightworks.

Once we have worked through the detailed planning with our contractors, we will be back in touch with you about what is proposed. Sign up for our regular updates. You can also email us at: SH1Waikato@nzta.govt.nz.

We don’t want to see your crack

We don’t want to see any cracks in windscreens so where the new chip is down, slow down. 

SH1 Desert Road still has significant areas where the chipseal needs to bed in with traffic driving over it so, to avoid those cracks, slow down and stick to the temporary speed limits and traffic management. You should also keep your distance from the car in front, ideally 3 car lengths or more. 

There has been some debate about what is more likely to cause a cracked windscreen. The speed you're traveling at, or the speed the vehicle that spits up the stone is traveling at? It’s not a trick question. Both of them have an impact, but you can be certain if you’re going slower, there’s less chance of seeing that crack or chip.

Putāruru to Lichfield: Digging deep to create a smooth ride

What a difference a week makes. Check out these progress photos from Putāruru to Lichfield showing the dig out that was started last week and now the subgrade and subbase being worked on. There are four layers that make up a road. The subgrade, subbase, basecourse and surface. In many places the work we’re doing on SH1 Tīrau to Waiouru goes far deeper than just resurfacing the road, we’re rebuilding it back stronger.

In the areas below, we dug out the road to the subgrade level because it was soft and needed working to make it stronger and ultimately create a smoother road surface that lasts longer and isn’t prone to potholes. After digging it out, we use geotextile fabric to reinforce it before adding the aggregate and then the basecourse material. Then we’ll apply the first coat of seal before opening it for use.

We still need to return, next construction season, after the first coat seal is bedded, to complete the final surface and give drivers that smooth ride. The second coat also provides a thick, durable layer of chipseal, waterproofing the surface underneath. This process prevents ‘flushing’, which is where the bitumen rises to the surface of the road, making it shiny and slippery. 

Please follow the detours in place and stick to the speed limits.

Ātiamuri to Wairakei: Busy times

Work is ramping up between Ātiamuri to Wairakei with 5 separate work sites underway. This week we focused on dig outs, drainage works, kerb and channel and guardrail repair and replacement. These photos show why the road is closed. You’d be waiting in traffic at stop/go for a very long time trying to navigate this lot. The photos below show new subsoil drains being laid, dig out areas and aggregate ready to be applied. 

Please follow the detour routes and keep to the speed limits.

Introducing some of the T2W crew

We have some great people working on our Tīrau to Waiouru Accelerated Maintenance Programme (T2W). They’ve been handpicked for their specialist skills and are passionate about the work they do. They’re committed to delivering road users a better driving experience on the sections of SH1 they’re working on.

Richard is a machine operator in the asphalt team for Downer. He’s been working on SH1 at the Desert Road. He describes it as putting the icing on the cake. 

“I love what we do with the team...Everyone is doing their part on the job. It’s a good feeling knowing that it’s smooth...”

Fabric sealing: A good underlay

Even asphalt needs a good underlay at times and on SH1 Desert Road we’re sealing success by using special fabric that helps us to build waterproof roads. 

Chipsealed roads are waterproof and are designed to encourage water to move off the surface and into drainage. There are some pavement types that need a little bit of extra help to keep them dry, and that’s where fabric sealing helps. 

The fabric seal provides a nice, smooth and consistent surface to lay chipseal on, which slows the formation of cracks, and protects the lower layers of the road from damage if water does manage to make its way through the surface. Ultimately this means the road will last longer. 

A FDV (fabric delivery vehicle) [the tractor thing in the photos] is used to roll the fabric directly on top of bitumen binder, gluing the fabric to the road. A further layer of binder is then spread on top of the fabric, before the chip is laid on top then rolled in. This becomes the surface we drive on.   

Not all our roads need this underlay, and we work with our road designers and engineers to determine where we should roll it out. Due to previous instances of cracking and ‘binder rise’ or ‘pavement flushing’ (where the binder comes through from the lower layers of the road and settles on the surface we drive on) we decided to install the fabric seal on the Desert Road. Over 16,500 square metres across 3.5 lane km was rolled out over the last week.

Great barriers: Clever engineering to keep you safe

We’re breaking all sorts of barriers on SH1 Tīrau to Waiouru, delivering the largest road renewal programme we have ever delivered in 1 season.  We think our actual barrier work is also pretty clever.  

We’re repairing, and where needed, replacing road barriers in almost all the sections of SH1 we’re working on. We’ve also been upgrading the terminal ends of these barriers in many places. Those are the curved bits you see at the end of a barrier. We’re replacing them with new and improved terminal ends that can absorb a huge amount of energy if they get hit by a vehicle, transferring the energy out of the moving vehicle and into heating and bending steel.

Mechanisms within the terminal are designed to take the force of the impact, then compact the barrier with special bolts shearing off as the energy passes through, compressing the barrier as it goes.

On Tīrau to Waiouru, we’re also moving away from rigid barriers on our bridges. Usually bridge barriers are made up of reinforced concrete walls or metal rails on concrete parapets. The exposed ends of these bridge barriers pose a significant hazard if vehicles hit them. On these ends we’re using approach guardrails; curved guardrails that shield the rigid ends of the bridge and prevent vehicles from impacting with them, guiding them instead to slide around rather than impact directly. We hope you never need to use this clever engineering.

Road worker of the week

Each week on our social media we profile one of our road workers from projects across the motu. This week Dre, Traffic Manager on Tīrau to Waiouru took centre stage. 

Dre's role with Downer Group sees him managing temporary traffic management (TTM) operations across approximately 220 kilometres of SH1 from Tīrau in Waikato to Waiouru in Manawatū-Whanganui. Since September we’ve delivered over 80 lane kms of road rebuilding and resealing. With 2 sections of road currently closed, and the Desert Road just reopening, this has required a high level of leadership and collaboration to ensure everything runs smoothly at each site.

More information

This work forms part of the government’s $2.07 billion investment into road and drainage renewal and maintenance across 2024-27 via the State Highway Pothole Prevention fund.

Please pass this on to others who may be using SH1 in the next few months and encourage them to sign up to this newsletter by using the subscribe button below.

For more information or any concerns on the SH1 Tīrau to Waiouru maintenance, please email us.

Visit our website nzta.govt.nz/t2w

Check out Journey Planner before you leave for your travels - it will show you the best routes!