The Kererū Gorge culvert in Hawke’s Bay, vital for connecting a Hastings community severed by Cyclone Gabrielle, has reopened after a rebuild that ultimately cost $30.3 million. This is significantly higher than the initial estimate of $13.5 million.
The Background
Cyclone Gabrielle in 2023 caused “catastrophic” damage to the Kererū Gorge, washing away a 50-meter section of Kererū Road and creating an 18-meter-deep gully. For over two years, residents relied on a winding, gravelly detour to access their community. The newly completed 15-meter-wide segmented culvert restores a crucial link, but at a substantial financial increase.
The additional $16.8 million in costs were fully covered by the National Infrastructure Funding and Financing. According to the Hastings District Council, the increase stemmed from unexpectedly unstable ground conditions that necessitated design changes and caused significant delays. Over $27 million of the total cost went to contractors, equipment, and materials, while just over $3 million covered design, consulting, environmental studies, and land acquisition.
Darren de Klerk, the council’s director of infrastructure delivery, explained that initial estimates were based on typical rates for similar structures, made before the extent of the damage was fully understood. “As the first test piles were drilled, we discovered the ground was much less stable than expected,” he said, leading to a more complex and costly project.
The situation required significant engineering adjustments, including reinforcing the structure, diverting streams, and stabilizing the soil. One pile alone required 75% more concrete than originally planned. De Klerk noted that under normal circumstances, a project of this scale would require one to two years of investigation and design *before* construction began. However, the urgency of the situation meant the project was essentially built “while flying the plane,” with engineers working just weeks ahead of construction crews.
Other Hastings District Bridge Rebuild Costs
Information released alongside the Kererū Gorge culvert costs indicates that other post-cyclone bridge and culvert projects in the Hastings district have largely remained within their initial budgets. The Moteo-Puketapu bridge came in at $26 million, slightly under its $28 million estimate. The Chrystal Twin Culvert cost $3.4 million, compared to an estimate of $3.5 million. The Matapiro Bridge rebuild was remarkably under budget at $5.07 million, compared to an initial estimate of $9 million. The Patoka Culvert cost $2.5 million, slightly over its $2.3 million estimate.
Frequently Asked Questions
What caused the cost overrun on the Kererū Gorge culvert?
Unstable ground conditions discovered during construction led to significant delays and required substantial changes to the original design, resulting in the increased cost.
How was the additional cost of the culvert funded?
The extra $16.8 million was 100% funded by the National Infrastructure Funding and Financing.
Were other Hastings district rebuilds also over budget?
Information indicates that other bridge and culvert rebuilds in the Hastings district have largely been constructed near to, or below, their initial estimates.
As the Hastings District continues to rebuild following Cyclone Gabrielle, will the lessons learned from the Kererū Gorge culvert project inform future infrastructure planning and budgeting decisions?
