Taller tunnels for Kaiko¯ura coast
Taller tunnels on the Kaiko¯ura coast will mean some truckies can finally get their toot on behind the wheel.
The two sets of tunnels on State Highway 1, south of Kaiko¯ura, are set to gain 300 millimetres in height.
The Rairamai and Paratitahi tunnels were damaged during the November 2016 earthquake and the upgrade is part of their repair work.
New Zealand Transport Agency earthquake recovery manager Tim Crow said the repair work was already underway.
The tunnels currently had a clearance of 4.3 metres, but their new height would be 4.6m. Their 3.5m width would stay the same.
‘‘We had some rock come down inside [the tunnels] so what we’re doing is we’re going in and rock anchoring, netting and lining to make sure any loose rocks are nicely locked into the structure,’’ he said.
The height would be gained by squaring up parts of the tunnels.
‘‘They have always been a bit small, trucks that go there clip often so we’re taking this opportunity to increase the size so that there is better clearance for heavy vehicles,’’ Crow said.
Following the 2016 quake, NZTA considered removing the tunnels, but environmental and cultural significance meant they had to stay.
‘‘The whole idea of removing the tunnel is called ‘daylighting’ and we couldn’t do that as there are roosts on that peninsula and the area had Ma¯ori fortifications in the past,’’ Crow said.
Motorists had taken to tooting in the tunnels, either for fun or for loved ones, as they made the coastal journey.
Finishing the work would take at least six months and traffic would be managed by using one tunnel while the other was being repaired.
The repairs were part of the $231 million post-earthquake improvements package by NZTA.
The increased height was good news for some truckers.
Road Transport Forum NZ chief executive Ken Shirley knew it was coming, but was pleased nonetheless.
‘‘The vehicle dimension and mass rule, called the VDAM Rule (vehicle dimensions and mass rule) on any vehicle is 4.2m height and at 4.3m it’s inadequate clearance.
‘‘If you’ve got less than 200mm clearance and if you’ve pumped your tyres up full and you have a bit of a bounce you would rise and fall on your springs about 200mm and scrape the top of the tunnel, so moving that out by an additional 300mm is a good move and certainly supported by our industry,’’ Shirley said.
But the increase in height would not be enough for all trucks, NZ Heavy Haulage Association chief executive Jonathan BhanaThomson said.
Oversize vehicles would still have to travel the long way, he said.
‘‘In our earlier proposition to NZTA we were hoping for much wider and higher tunnels for oversize loads.
‘‘At the moment anything [oversize] that has to go from Picton to Christchurch has to go through the inland route, while it’s shorter and more efficient to go down the coast,’’ he said.
The association wanted the tunnels to be 5m by 5m. ‘‘What they’re offering is the absolute minimum,’’ Bhana-Thomson said.
Meanwhile, the $60m project launched by the Government last year to improve the alternate highway was expected to wrap up before winter, leaving State Highway 63, 6, 65 and 7 in much better condition, should there be another highway-closing disaster.