Significant changes to the road layout on State Highway 1 in the Puhoi area are scheduled to take place as part of the Ara Tūhono – Pūhoi to Warkworth project.

The focus for the southern end of the project is completing the construction of the Pūhoi on and off-ramps.

“This next phase of the project involves changing the current northbound road layout at the Southern Connection as the team works in areas currently used by SH1 traffic,” Waka Kotahi NZ transport agency said today.

Northbound travellers will exit at the Pūhoi northbound off-ramp and be directed onto a short section of Pūhoi Rd before moving onto the existing SH1.

The new Pūhoi to Warkworth motorway. Photo / Waka Kotahi

Whereas southbound traffic will continue to use the same route, however, the southbound Pūhoi on-ramp will move towards its final layout of one lane with northbound traffic no longer using the ramp, Waka Kotahi said.

This Sunday, March 26, night works will be carried out to reconfigure the road layout at the Pūhoi off-ramp.

“The new road layout will be in place from the morning of Monday, March 27 and remain in place until the safer, more resilient and reliable motorway opens in the coming months,” Waka Kotahi said.

There are night works associated with new layout changes in the south and tie-in works in the north. Waka Kotahi asks commuters to plan ahead for the following closures between 9pm and 5am:

• Full SH1 northbound and southbound at the Johnstone Hill Tunnels, signposted detours via Hibiscus Coast Highway or SH16: Sunday 26 March - Thursday 30 March Sunday 2 April - Wednesday 5 April Tuesday 11 April - Thursday 13 April
• Full SH1 closure northbound and southbound from Warkworth to Wellsford, signposted detour in place via SH16, this detour will add up to 30 minutes to the journey: Sunday 26 March - Thursday 30 March

The highly anticipated "Ara Tūhono" motorway is due to open in April or June.

Waka Kotahi asked road users to take care while they adjust to the new road layout and adhere to the temporary speed limits.

“Allow extra time when travelling through this area, especially during peak periods including Easter. People are encouraged to travel outside peak hours if they can or leave earlier than they normally would,” they said in a statement on Monday.

A temporary speed limit of 30km/h will be enforced, and there will be traffic management in place to assist with access to and from Pūhoi village.

After two Covid-impacted delays - it was due to open in the summer of 2021/22 and then at Queen’s Birthday Weekend last year - the motorway, named Ara Tūhono, or “connecting path”, is due to open in the coming months, chopping 11 minutes off the drive north.

The 18.5km route north is in a different league to the stretch of State Highway 1 it is replacing - like getting off a goat track onto a world-class motorway.

“The experience driving through will be awesome, it is such beautiful country and the road is striking,” says Waka Kotahi national manager of commercial delivery Andrew Robertson.

The motorway is expected to be a boon for the town of Warkworth, which is forecast to grow from a population of 6600 to more than 25,000 over the next 25 years. The town is already growing faster than the Auckland average and had 456 new homes consented in the past five years.

Motorway designed and built to handle storms

When the summer storms battered Auckland, the new Pūhoi to Warkworth motorway coped well but the existing state highway suffered significant slip damage.

When Cyclone Gabrielle pounded the region there were slips at Schedewys Hill, flooding in Pūhoi and multiple trees down. These events required lane closures.

By comparison, Waka Kotahi’s Andrew Robertson said the new motorway was relatively unscathed by the double punch, with a “few bits and pieces” on the new motorway requiring tidying up. On a drive along the motorway this week, the Herald saw the scars from a few small slips, but nothing major.

The new motorway has a stormwater system engineered and built to handle the terrain and a 1-in-100-year flood. It has 46 culverts, including the 11-barrel culvert structure for flood relief at the northern end; extensive swale drainage, and numerous stormwater ponds.

There’s also a porous asphalt surface to help with water run-off and about 1 million native plants have been planted to soak up water.

When the motorway is finished, Robertson said, it will be a safer, more resilient and reliable route between Auckland and Northland.

The 11-barrel culvert on the motorway. Photo / Waka Kotahi

Pūhoi to Warkworth motorway project by numbers

• $878 million - cost
• 18.5km - length
• 4 - number of lanes
• 100km - speed limit
• 7 - number of new bridges
• 10 million cubic metres - amount of rock and soil cut
• 7km - culvert pipe system
• 750 plus - number of workers at the peak
• 35,000 - number of vehicles per day on the new motorway and existing SH1 route by 2026
• April-June 2023 - fully opens to traffic