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Muldoon may have been tight, but the corner named after him is about to become less so. HUGH DE LACY explains.
The corner, 500 metres south of the Rimutaka summit on State Highway 2, got its name in the 1970s during a Parliamentary debate: it’s so tight that trucks going in opposite directions can’t pass on it. From the south it’s a right-hander, supposedly reflecting the near-dictatorial control Muldoon kept on the Government’s purse-strings, but from the north it’s a left-hander, like his policies of state control and suppression of competition. Whichever way it’s viewed, this major bottleneck on the main road between Wellington and the Wairarapa is currently the subject of a $16.5 million realignment that will take nearly three years to complete. The project has been on the NZ Transport Agency’s books for 10 years, and was originally scheduled for a start in 2012-13 but was brought forward by 30 months when money was made available through the Government’s Economic Stimulus Package. Opus International Consultants designed the project, which required exploratory holes to be drilled in the middle of the road, at the base of some of the retaining walls and on the spurs immediately above the road.
By December, however, the weather had settled, and Hawkins’ project manager Kevin Grey was confident the back of the project could be broken over the summer, with no threat to the mid-2012 completion date. Progress on the first of the two main cuts was well advanced and the second was scheduled to be opened up in the New Year. Kevin told Contractor that most of the material from the succession of cuts is being used as fill on the site, but some surplus will be carted up to four kilometres to other sites as part of an on-going programme to improve safety on the Rimutaka Hill. About 5300 vehicles use the road each day, but apart from the contractual requirement to minimise disruptions, environmental considerations are probably the main challenge.
Of prime importance to the project’s sustainability is the protection of the Rimutaka Stream from any disruption to the fish spawning cycle between June and August. A surprising number of species populate the stream, ranging from both short and long-fin eels to freshwater crayfish, dwarf galaxias and various types of bully. The re-alignment cuts through no fewer than five of the stream’s tributaries, which have to be protected by silt fences and the diversion of clean run-off from around the site until vegetation is re-established. There are two main fill sites, each of which will have a culvert – one 1350mm and the other 1600mm in diameter – that will have fish spoilers pre-cast into their bases, with the water flow controlled at the culvert outlets by pre-cast dissipation units bolted in situ, comprising concrete chambers 3.3 metres high, 5.6 metres long and 4.5 metres wide. Hawkins is utilising two project sites, one by the old tea-rooms at the summit, and the other a base camp down at the Kaitoke Country Gardens restaurant on the southern approaches to the hill.
“We may have to use explosives, depending on how difficult it is to get the rock out of the deep cuts, but it’s something everybody is shying away from at the moment,” Kevin says. Traffic management hasn’t been too difficult, in part because the absence of passing opportunities on the hill means that most trucks arrive with a stream of cars backed up behind them, leaving a useful interval back to the next lot. Even so Hawkins is using two traffic-spotters, one at the summit and one further down the south side, who are in radio contact with the plant operators so haulage across the road can be suspended until the traffic is past. The spotters’ work is supplemented by electronic sign-boards warning road-users of the work in progress. Traffic problems can arise when the road is swathed in mist and fog – something that happens with less frequency in summer – at which time plant has to simply stop crossing the road.
Muldoon might have been a hard man to get money out of, but the corner that bears his name will soon be a lot easier to negotiate.
Contractor Vol.34 No.1 February 2010 |
Depending on whether you’re coming from the north or the south it involves a savage swing to the left or to the right, but either way Muldoon’s Corner on the Rimutaka Hill road is as notoriously tight as the former Prime Minister and Finance Minister was with money.
Hawkins Infrastructure has the main contract for the cut-and-fill operation that involves excavating 220,000 cubic metres of material along a one-kilometre stretch that includes the corner from which the project derives its name. Work started in late August and initially progressed fitfully as wild weather kept engulfing the precipitous site, which is at an altitude of 550 metres and is savaged by two metres of precipitation a year. Snow and ice often close the road in winter, and violent winds can do the same at any time of year.
“Where we clear the site to enable us to cut and clear-to-fill, we stockpile all the shrubs and trees – some of them up to 20 metres tall – to be spread back over the new embankment,” Kevin says.
The company has about 20 staff working on-site operating several 30-tonne excavators and one 45-tonner, along with a D8 bulldozer with ripping teeth. Haulage is by three 25-tonne dumpers backed up by truck-and-trailer units. The predominant material is rock but so far it’s proved soft enough to be broken up by the bulldozer.
The project is designed to lift the recommended road speeds from the present low of 25kph in some places to 50-60kph, consistent with the Rimutaka Hill Corridor Management Plan. The road width will be increased to a 10-metre carriageway made up of two 3.5-metre lanes with 1.5-metre shoulders. There will be a number of other culverts besides the two big ones, and the four existing retaining walls will be upgraded. The existing uphill passing lane will be replaced with a slow-vehicle bay.