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A decision on the proposed $1.025 billion Transmission Gully northern approach to Wellington has been promised by Joyce for this year, and until it’s made the route to be taken from Waikanae south can’t be determined.
Preliminary work suggests that, cost-wise, there’s not much to choose between these options, and argument has raged for years over which is better. From Waikanae north the problem is simpler – because the hills retreat from the coast – though also expensive: four-laning the existing State Highway 1 for about 35 kilometres. At up to $3.6 billion, including works stretching out beyond the Roads of National Significance 10-year horizon, the 100 kilometre Wellington project is by far the most costly of the seven designated. Wellingtonians have been griping about congestion north of the city for decades, though the problems of getting through the city to Wellington International Airport in the southeast have been alleviated lately by the completion of the inner-city bypass. Joyce has indicated that NZTA is likely to give immediate priority to the four-laning north of Waikanae, which will at least get the greater project under way while the Transmission Gully/coastal highway conundrum is untangled. He stressed that it was important that the various parts of the project south of Waikanae be tackled in the right order. “It would be a pity if everybody thought they had signed up to Transmission Gully and that was going to solve all the Wellingtion northern access issues, only to find that, at the Waikanae lights, at the Otaki roundabout, at the Paraparaumu lights all the problems they had previously experienced were still there,” he says. Transmission Gully takes its name from the route of the Haywards-to-Bunnythorpe 110 kilovolt electricity line. The preferred route, heavily supported by Wellingtonians in an NZTA survey last year, begins just south of the notorious MacKays railway crossing, curving eastwards up the Te Puka Stream valley and over the Wainui Saddle. It then follows the Horokiwi Stream down to the Battle Hill Farm Forest Park, past the Pauatahanui golf course before swinging west to cross State Highway 58 southeast of the existing Pauatahanui roundabout. It then climbs into the headwaters of Duck Creek, crosses Cannons Creek near the Takapu Road electricity sub-station, and scales the hills above Ranui Heights before dropping to join State Highway 1 at Linden. This route was settled on three years ago, varying in places from the one originally designed in 1996 and shaving about $275 million from original cost estimates while producing better environmental and safety outcomes. The four-lane highway with central median barrier would cut peak travel times from Kapiti to Wellington by about 10 minutes, from Kapiti across to the Hutt Valley by 15 minutes, and from Porirua to the Hutt Valley by five to seven minutes. It would largely avoid the remaining stands of native forest, and reduce and shorten the number of stream crossings, while giving easier access to regional parks like Battle Hill. Overall the benefits of Transmission Gully may outweigh the costs, but even if it plumps for the coastal upgrade option the Government faces its biggest problem in just finding the money. Next: The Christchurch motorway projects
Contractor Vol.33 No.5 June 2009 |
The alternative to Transmission Gully is the upgrading of the existing coastal which either passes through medium-density housing areas or is jammed between steep hills, the North Island Main Trunk railway and the sea.