Editorial: Tranmission Gully no longer a pipedream

21:49, May 07 2012
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BUILDING UP: Traffic on the motorway is backing up, and can be seen from a Citylink webcam.

Tranmission Gully was once a pipedream. The "unaffordable" versus the "unconsentable" was how former regional land transport committee chairman Terry McDavitt once described the roading choices facing planners. The "unaffordable" was the inland motorway long mooted to shorten travel times between the capital and parts north. The "unconsentable" was the widening of the existing coastal route from two to four lanes.

Now the "unaffordable" has edged a step closer to reality with a board of inquiry signalling it intends to grant consent for the construction of a $930 million, four-lane highway cutting across rugged, broken country to link Linden to the Kapiti Coast. All going to plan, construction could begin in 2015 and be completed by 2021.

Short of Silicon Valley's giants setting up shop on the Miramar Peninsula, little better news could be heard for the capital.

As the board of inquiry, headed by Environment Court judge Brian Dwyer, concluded, the existing road north is inadequate. It is prone to delays, easily blocked, less safe than desirable and vulnerable to earthquakes and tsunamis. Tellingly, while the board heard arguments for and against the construction of Transmission Gully, none of those who appeared before it argued that the existing coastal route was satisfactory.

The route proposed for the new highway is not earthquake proof, but experts say it could be more quickly restored to working order after a quake and, once it has been built, it will increase the chance of the capital having an operable road north after a major natural disaster.

Rarely for New Zealand, the project also future proofs the region against population growth. For once a government has not insisted on the cheapest possible option. For that the National-led Government, and former transport minister Steven Joyce, deserve the thanks of all those who have been forced to detour over the precipitous Paekakariki Hill Road by a road-blocking vehicle crash, those whose final holiday memories are of crawling home in a traffic jam and those who would otherwise have lost relatives on the narrow coastal road.


The project is not without its downsides – most notably the cost and the 3000 tonnes of sediment that is expected to flow into the Pauatahanui Inlet during construction. But the first is unavoidable. A new road has to be built at some point whatever happens to the coastal route. The second is a matter of point of view. Increased sediment flow will damage the Pauatahanui Inlet – the only large area of salt marshes and seagrass in the Wellington region – but the damage will be offset by the long-term benefit of reduced siltation once trees planted in association with the project are established.

The Government has grasped the nettle. The board of inquiry has sifted the temporary drawbacks of the project from the long-term benefits. Hopefully objectors will see the big picture.

The capital needs a secure, modern link to the rest of the North Island. The sooner construction starts the better.