Auckland to Waikato expressway finally opens

The road upgrade has cost $83m. Click on 'more pictures' below for maps of the new route.

Motorists should get a clear run from this evening on what was once one of New Zealand's deadliest stretches of highway.

They will be able to drive from Auckland to Rangiriri at 100km/h, after years of frustrating speed restrictions along the previously winding and uneven 12km section of State Highway 1 which follows the Waikato River from Mercer to Long Swamp.

Heavily enforced limits of 50km/h in construction zones and 80km/h elsewhere have helped reduce the carnage on a road previously dogged by multiple-fatality crashes - from 18 deaths between 1996 and 2000, to seven in the past 5 1/2 years.

Police described it as a "goat track", hard for drivers of the 17,500 vehicles using it daily to adjust to at the end of the Southern Motorway, and made more dangerous by winter fog.

But once Transport Minister Annette King opens the $83 million Mercer to Long Swamp dual carriageway today, southbound traffic will have two lanes of new highway to itself, without having to face vehicles coming the other way.

Opposing traffic will be separated by a grassed median up to 10m wide, except beside the Meremere power station site, where a concrete crash barrier has been built because of the reduced amount of space able to be left between carriageways.

Perilous 75 degree bends have been straightened and five intersections upgraded, although it will be years before all access to the road is through motorway-style ramps, such as those at Mercer and Hampton Downs.

Upgraded intersections, such the turnoff to the Meremere dragway, have been given long acceleration and slowing lanes, but some will eventually be replaced with link roads to proper interchanges.

Northbound drivers will have to tolerate an 80km/h limit for a couple more years on 2km of the old highway between the Whangamarino River and Mercer, which is awaiting repairs under Transit NZ's maintenance budget to beat riverbank erosion.

At this point of the project, the two carriageways are separated by almost 300m.

Northbound traffic stays close to the river, but southbound motorists go through a deep cut in the hills behind Mercer.

They will drive past a full interchange at the town then go over a new 70m railway tunnel and through the hills before the carriageway meets the northbound lanes, after sweeping down a bridge across the Whangamarino River.

Curved off-ramp

Southbound traffic stopping at Mercer or going over the Waikato River will leave the highway up a curved off-ramp.

The creation of this interchange has enabled the closure of a dangerous railway level-crossing which divided Mercer's settlement from its shopping centre.

The project is one link in the $1 billion-plus Waikato Expressway.

Transit expects to have to spend a further $900 million building dual carriageways and bypasses around Rangiriri, Huntly, Ngaruawahia, Hamilton and Cambridge.

It is the third part of the expressway to be completed, after an 8km stretch between the Bombay Hills and Mercer, and 9km between Rangiriri and just north of Huntly.

The next step is a 3km bypass around Rangiriri.

Investigation of this will start this year and construction will begin within five years.

Transit and its contractors are hugely relieved at having got the most difficult section behind them, after a fraught 5 1/2 years of on-and-off-again construction complicated by financial, geotechnical, environmental, climactic and even cultural challenges.

The project began early in 2001, but was halted 10 months later, when a section of the route at the southern end began sinking into the aptly named Long Swamp, twice as quickly as predicted.

The project remained stalled for seven months until the Government's transport funding agency yielded to pressure from Waikato mayors and granted $20 million extra to finish the job.

Even after the extra money was approved, the project hit a cultural snag, stalling work on a 100m section south of Meremere briefly late in 2002 after local Maori expressed concern about its potential impact on a taniwha, or guardian spirit, of the Waikato River.

The interruption drew a scornful reaction from critics of the Resource Management Act, but Transit says it did not have to realign

Instead, it says, it used rock instead of earth to preserve extra wetland in a move which added only about $20,000 to a $83 million project.

It also had to defend a decision to build a 2km section at Long Swamp by 2003, before the rest of the project, saying a delay would have stopped the opening of a large new landfill by developers who contributed $4 million to the Hampton Downs interchange.

Although motorists have yet to deliver their verdict, his sentiment is at least shared by Mercer's volunteer fire brigade.

Acting deputy fire chief Richard Logan, who soon after joining up in the mid-1990s was called to a crash in which five people died, said of the new road: "From a brigade point of view we are as happy as hell."