The full closure of SH58 between State Highway 1 Transmission Gully and State Highway 2 was planned to enable the SH58 Safety Improvements Project to complete a major rebuild of a 130m-long section of the highway.
Options to complete this work were analysed under NZTA’s risk-based guidelines to TTM.
New Zealand guide to temporary traffic management (NZTTM)
SH58 Safety improvements: April 2023 Road Closure
Closing the road for a weekend was compared with the traditional compliance-based TTM approach of working over several weekends under stop/go. Considering safety, efficiency and the impact to journeys, the one weekend closure came out as the preferred option.
The proposal was supported by traffic modelling that predicted the weekend travel times would be similar to weekday peaks with up to 30 minutes delay from one end of SH58 to the other end via SH1 and SH2. Travel times were monitored by WTOC and the project team with the result being similar to the model.
During the closure, other project works were also completed by the Downer crews, reducing the need for future stop/go traffic control. The Wellington Transport Alliance team also made the most of the opportunity to work on maintenance while traffic was diverted. Closing the road for a weekend made this work much more efficient and much safer for people.
SH58 is the key east-west connection for the Wellington region, joining Porirua and Kāpiti with the Hutt Valley. Closing it meant significant extra traffic using SH1 and SH2 via the Ngauranga Interchange to travel across the region.
In anticipation of this, a five-week long, region-wide advertising and communications campaign was launched by the NZTA project team. The NZTA Communications & Engagement team worked alongside the on-site project team who informed local residents and businesses along the highway. Local access and emergency services access were maintained throughout the closure.
Here is some of the feedback from members of the public:
130 people worked day and night across four shifts, with 65 people on site at any given time. The work was completed early and the road was reopened ahead of schedule on Sunday night.
Closing SH58 for planned road works is a new thing for the Wellington region, but closures are set to become more common across our network as we increase our focus on safety for road crews. Removing passing traffic for a night, or a weekend, means a significant risk is removed, and also makes the work more efficient.
The SH58 closure follows from the overnight closures of SH2 over the Remutaka Hill which are now a regular occurrence enabling safe maintenance work on that road.
Over the weekend, road crews achieved the following:
SH58 safety improvements project
