Race to build $52m city underpass

Tauranga could be plunged into a traffic gridlock if plans are delayed to relieve pressure on a city intersection used by trucks to carry freight worth $3 billion a year to the Port of Tauranga.

Plans have been unveiled to solve traffic woes that have blighted the Hairini Interchange ever since Welcome Bay developed into a major suburb 30 years ago.

The long-overdue project to separate highway traffic from suburban traffic accessing Welcome Bay and Hairini has reached a pivotal point.

Evidence was heard yesterday on the New Zealand Transport Agency's plan to build a $52 million underpass directly linking Welcome Bay Rd to the Hairini causeway and Turret Rd. The road would cut through the interchange, under State Highway 29. And time was of the essence, according to a report to the independent hearings commissioner Greg Hill, who is tasked with weighing up the evidence and recommending the route designation.

Based on existing evening peak traffic delays at the approaches to the Hairini Roundabout and Welcome Bay Rd, congestion levels reached by 2016 were predicted to accelerate to "total gridlock" in a relatively short time.

"This conflict has the potential to bring 15th Ave, Fraser St and then the Tauranga CBD to a standstill if vehicles are not offered an alternative route," project manager Neil Mason said.

He said SH 29 was a national strategic route because it carried more than 1200 heavy vehicles a day. This represented more than two million tonnes of freight worth $3 billion to the port every year. If the designation went according to plan, the underpass would be finished in 2016 - a year before the interim solution of traffic signals through the Hairini interchange was predicted to be under major pressure. The option chosen by the agency following consultation with the community added a signalised intersection at the underpass link with Welcome Bay Rd.

This offered flatter gradients up to where the underpass went beneath SH 29 and better sight distances but required 190,000 cubic metres of fill to be placed on the Welcome Bay side of the new road.

Mr Mason said the underpass would extend the operational capacity of SH 29 and the Hairini/Maungatapu roundabouts to at least 2031.

However, the agency has stuck to its intention to wait until the bypass was operating before it reviewed the last stage of the Hairini Link project - the four laning of Turret Rd and 15th Ave including a new bridge.

"This review is likely to be needed in approximately five to 10 years."

Beca consultant planner Keith Frentz said the future traffic pressure would come from the significant residential and commercial growth in the Welcome Bay, Ohauiti and Tauriko areas coming into conflict with regional traffic.

Mr Frentz said the underpass would be a two-lane road that was future-proofed so it could be widened.

The preferred option reduced the need for a significant land take, was further away from the Te Pahou Urupa (cemetery) at Hairini and had less impact on cultural and other values.

Timetable

Route designation 2012-13

Design and tender 2013-14

Construction start 2014

Opens 2016