After an ‘atmospheric river’ dumped a metre of rain in just four days across the top of the South Island in August 2022, the decision was made to enact a 48-day full road closure for the complete repair and enhanced resilience of SH6.

With hundreds of moving parts to orchestrate, meticulous planning and Waka Kotahi’s full support, Fulton Hogan – with WSP and hand-picked subcontractors – achieved in that short window what would normally take up to 18 months under a traditional tender-design-build process.

In doing so, they minimised the inevitable social, economic and environmental pressures. The approach – and its execution – shows how lateral thinking can achieve new levels of flexibility, speed, efficiency, environmental benefit, public utility and asset quality. It also shows how reinstatement is an opportunity to address historical realities – in this case a state highway build on the path of a former stagecoach route.

The approach combined certainty with flexibility. Certainty came from a design freeze once the concept was agreed. The flexibility came from the ability to reduce or add activity at key junctures. Rather than using it as a ‘safety valve’, the team embraced this operational flexibility by adding two significant elements to the four retaining walls, river realignment and multiple culvert replacements outlined in the plan. These additions were removing 20,000m3 of spoil from an active slip above the road and making the Red River alignment permanent.

Although managed from Nelson, the design process was accelerated by having a different WSP office designated to each structure and the design work sent to teams in the Philippines for drawings overnight, a seamless 24/7 operation.

The key was having design and construction done as one, by the people who would also ‘own’ the project management throughout. Four project cornerstones were:

Trust. Waka Kotahi entrusted Fulton Hogan, an existing maintenance supplier, to deliver the work within a very tight timeframe.

Intensive planning. The period between the flood and the beginning of the road closure was maximised for planning on all aspects, including preparing for foreseeable eventualities for those living in and near the closure.

Contingency planning. Multiple ‘off-ramps’ and ‘on-ramps’ enabled the 120-strong team to pivot, as necessary, at any critical juncture.

Resourcing. Fulton Hogan’s ability to bring its teams from six regions to supplement the core Nelson team, and best-in-class subcontractors who gave the project their undivided, 24/7 attention throughout was critically important. In all, over 120 staff were brought in at short notice.

Associate Minister of Transport Kieran McAlnulty described the completion of the SH6 repairs ahead of schedule as a “massive effort” fixing the five major sites that were damaged in the August weather event in just seven weeks.

“Seeing the repairs in person made it even clearer to me how major the damage had been, with whole sections of the road having to be rebuilt from the foundations up,” he said.

“On top of the repair work, Waka Kotahi has also used the time the road was closed to increase the resilience of the route. Over 30 new culverts were installed, along with new erosion protection measures.

“To get that done inside the timeframe available speaks to the skill and dedication of the crews involved. Thank you to the 120 contractors who worked on the site through all hours and weather to keep things on track to reopen the road on time.

In addition to central government recognition, at the 2023 CCNZ National Awards, our team that rebuilt sections of SH6 between Marlborough and Nelson in just 48 days achieved their own ‘threepeat’. They won their third major award in three months, with CCNZ’s $5 to $20 million project category.