Why aren't we there yet? The road New Zealand already replaced — and the one it should replace next.
- Grant McLachlan
- 4 days ago
- 3 min read
Nearly nine years ago, a hillside above the Manawatū Gorge moved and a road closed permanently. New Zealand spent $824 million building the replacement that should have been commissioned a decade earlier. The Remutaka Hill Road deserves the same honest conversation — before, rather than after, the hillside decides to have it for us.
The Manawatū Gorge Road had been a problem for years. Engineers monitored slope instability. Maintenance crews patched slips. Emergency closures accumulated — 26 of them between 2011 and 2017 alone. When the hillside finally failed permanently, none of it was a surprise to anyone who had been paying attention. What followed was nearly nine years of detours over the Saddle Road, adding distance and cost to every journey, while New Zealand built the road it should have commissioned before the crisis, not after it.
Te Ahu a Turanga: Manawatū Tararua Highway opened in 2024 at a final cost of $824 million — up from an initial budget of $620 million, with the increase driven by construction inflation and added project scope. It is an excellent road. It also serves approximately 5,000 vehicles a day — roughly half the traffic the Remutaka Hill Road carries on an average day, and a fraction of what it sees on a busy Friday evening or summer weekend.
The Remutaka Hill Road is the same story, a chapter behind. The same greywacke and argillite geology. The same pattern of active slope movement. The same institutional response: monitor, maintain, manage, repeat. The road closes five to fifteen times a year, forcing traffic onto the Pahiatua Track, out via the Manawatū Tararua Highway, or north through Hawke's Bay — detours considerably longer and more costly than the Saddle Road alternative that frustrated the Manawatū for seven years. A Featherston resident rerouting to Wellington adds well over an hour each way. A freight operator faces a significantly longer run on every trip.
Multiply that across the estimated 2.9 million vehicle movements that use the Remutaka corridor each year and the economic cost is substantial — tens of millions of dollars annually in increased transport costs, schedule disruption, perishable freight losses, and business activity that simply doesn't happen because the road cannot be relied upon. And that is just the cost of the closures we already know. The more pressing question is what happens when the Remutaka produces its version of the 2017 Gorge failure — a slip significant enough to close the road for months rather than hours. The Wairarapa would cope, as the Manawatū coped. But based on the detour options available, it would hurt more, for longer.
The solution is neither exotic nor unaffordable. A replacement corridor of approximately ten kilometres — incorporating a tunnel through the most geologically active section — would reduce the Kaitoke-to-Featherston travel time from eighteen minutes to under seven, and effectively eliminate the closure risk.
It is worth remembering that both the Remutaka Incline and the Rimutaka rail tunnel were built with pick and shovel; modern tunnel boring machines and AI-assisted road alignment software have reduced the time and cost of such work dramatically.
Beyond resilience, the economic upside is significant. Featherston would sit forty-three minutes from Lower Hutt on a modern, reliable highway. The Wairarapa's wine country, its agricultural sector, and its growing residential population would all benefit from the kind of accessibility that the current road actively suppresses.
The investment logic is straightforward, and more compelling here than it was in the Manawatū. Te Ahu a Turanga was justified on a benefit-cost ratio of between 1.2 and 1.6. An equivalent analysis of the Remutaka — at double the traffic volume, with worse detour alternatives, and with greater induced economic benefits from improved access — produces a benefit-cost ratio approaching three. On every measure that justified the Manawatū investment, the Remutaka case is stronger.
New Zealand paid dearly to learn that deferring a necessary road replacement doesn't make it cheaper — it makes it more expensive, with years of inadequacy piled on top of the eventual capital bill. That lesson, expensively acquired in the Manawatū, should be applied here while there is still time to apply it on our terms. The first steps are modest: a geotechnical assessment of the current alignment and a LiDAR survey of replacement corridor options. Neither requires a large commitment, and both produce information that is valuable regardless of what decision follows.
The Manawatū Gorge Road kept closing, and closing, until one day it didn't reopen. The Remutaka Hill Road is closing too. The question worth asking now is not whether we can afford to replace it. It is whether we can afford to wait.
To view a business case for the Remutaka Hill Road replacement, please download the report here:
