Ruby Bay: A gem of a project

On the books since the late 1990s, and suspended in 2002, the Ruby Bay bypass is at last underway.   HUGH DE LACY reports.

It’s not often that a state highway realignment involves as much as nine kilometres of greenfields construction, but that’s the case at Ruby Bay, between Richmond and Motueka at the top of the South Island.

The $30 million project extends an earlier upgrade from Richmond to Mapua, completed in 1999, by swinging inland from the point where the existing State Highway 60 turns east to Mapua then north along the Ruby Bay coastline.

The realignment in effect defines the boundary between the rural/residential areas along the coastline and the forestry areas to the west, and in doing so reduces what had once been no fewer than 145 access points along that stretch of highway to just 11.

Running from Trafalgar Road in the south to just west of Tasman village in the north, the 10.7 kilometre realignment includes four passing lanes – two in either direction – and boosts to 100kph capacity a road that was previously notorious for the frequency of the speed restrictions it imposed on the 6000-7000 vehicle movements it carries a day. Much of this traffic is commuters heading into Nelson from the Mapua and Ruby Bay townships, supplemented by tourist and farm traffic heading over the hill to Takaka.

There are no bridges on the realignment but it features no fewer than seven major culverts of precast double-box structures with internal dimensions of three metres by three metres. Four of these are for drainage into the Ruby Bay estuary, but two are pedestrian underpasses and the seventh combines both functions.

The traffic lanes are 3.5 metres wide with shoulder widths of 1.5 metres.

The project is being managed by Andrew Adams for the client, the New Zealand Transport Agency (NZTA), while Matthew Taylor represents the designer, Opus International, and Marc Papke is project manager for the contractor, Downer EDI Works.

The work was first scoped in 1997 and delivered three or four options, including further development of the existing highway flanking Ruby Bay.

“In the end the client chose the one furthest away from the rural and residential developments, and from a project point of view it features that large area of greenfields construction, most of which involves earthworks,” Opus’ Matthew Taylor told Contractor.

Work was originally scheduled to start in 2002 but was suspended for five years five years before it finally got the green light.  The contract was finally awarded in September of last year and work started two months later. The contract specifies completion by December of next year, but if the weather is kind it’ll be finished earlier than that.

Downer EDI Works’ approach to the work has essentially been to start in the middle and work outwards, and involves the whopping total of 1.2 million cubic metres of spoil being moved. The overwhelming bulk of this was straight cut-to-fill within the greenfields area, although 40,000 cubic metres had to be transported across the existing highway. While aggregates for the paving, which began in March, are being brought in from local quarries, all the material unsuitable for structural fill has been contained on the margins of the site.

By the middle of last month 90 percent of the earthworks had been completed, with Works’ Marc Papke thanking a good run of weather over summer and winter for the rapid progress. September, however, was wet and October shaping to be even wetter, but Marc’s still confident of a finish eight months ahead of schedule.

Marc has run a staff of about 50 working in three crews, each comprising excavators, trucks, dozers and rollers, with two of the crews guided by GPS. The plant is all pretty standard with major items comprising four bulldozers up to D7, eight excavators up to 30 tonnes, five standard and six articulated dump-trucks, three graders and eight rollers, as well as the usual assorted watering and fuel trucks.

The five standard dump-trucks are old Caterpillar 769 50-tonners that first saw service on the Upper Waitaki hydro scheme around Twizel in the 1970s, and have proven ideal on this project.

“They’ve got a tremendous payload, and even though they’re fairly old they’re reliable and well-maintained,” Marc says.

NZTA’s Andrew Adams, whose previous project was the handsome Awatere Bridge on State Highway 1 south of Blenheim, says major constraints on the Ruby Bay project were environmental and archaeological considerations.

“The project touches on the estuary in three areas, all of them on live sections of the highway, and we’ve put in a lot of work minimising run-off from the earthworks,” Andrew says.

One part of the project involved a 300 metre diversion of a stream, which required the rounding up and re-location of nearly 1300 eels and other freshwater species. Another factor has been the need to suppress dust, with the water for this coming from two private dams and the several creeks the road crosses.

Given the importance of the estuary as a traditional Maori food source, a sharp lookout had to be maintained for anything of archaeological significance, with both local iwi and a project archaeologist maintaining a watching brief. However, apart from several middens, the only item of significance was what at first looked like a coffin unearthed by excavator driver Dave Vass. It turned out instead to be a small, oblong estuarine punt of European design that seemed to have been swamped in silt – probably during a flood – some time between 1890 and 1915.

Another important consideration for the construction team has been keeping the local community informed and, where possible, involved. Monthly meetings have been held to keep the locals abreast of developments, and school-children have been given the chance to assist in the planting of batters and creek banks.

With the bulk of the earthworks behind it and paving of the greenfields sections well under way, Works is now looking at the tie-ins with the existing roads at either end of the realignment – and that means getting back to the usual reality of coping with highway traffic flows.