Barrier solution gives cars access to SH30 Kōpaki bridge

An overweight truck using Kōpaki Bridge, in breach of weight restrictions. Photo / Waka Kotahi

An innovative solution has been found for the State Highway 30 Kōpaki rail overbridge, which will enable it to remain open to cars only.

This morning two chicanes are being installed at the northern and southern approaches to the bridge. Each chicane requires drivers to weave between the barriers at a crawling speed.

“We have deliberately made this chicane tight and difficult to navigate so that only cars without trailers can get through,” says Waka Kotahi NZ Transport Agency Regional Manager Maintenance and Operations, Rob Campbell.

“Wider, longer or towing vehicles, even if they weigh less than 6 tonnes, will need to take the detour.”

Last week Waka Kotahi announced that due to its deteriorating condition and the persistent breaching of its weight limit, the bridge would have to close to all traffic from today because overweight vehicles continued to ignore warnings not to use it.

Since then local contractor Inframax has come up with the unorthodox chicane solution.

“It’s extremely unusual to be installing a physical barrier such as this on a state highway, however we’ve seen over the past year that some drivers don’t respect weight restrictions, which means physically restricting access across the bridge is the only option to maintain some level of access for the local community.

“But if the barriers are interfered with, or other issues arise we will have no option but to revert back to a full closure of the bridge,” says Mr Campbell.

The closure had been announced due to the increased risk the bridge could collapse because of the heavy vehicles.

The timber bridge has been under a six-tonne weight limit since late 2021. However, Waka Kotahi NZ Transport Agency says repeated breaches of this restriction have accelerated the bridge’s deterioration.

The new bridge being built beside it is due to be completed in April. If it does have to be closed, all traffic between Te Kūiti and Maniaiti/Benneydale will need to use SH3, SH4 and Kōpaki Road, says Waka Kotahi regional manager of maintenance and operations, Rob Campbell.

The new Kōpaki Bridge is under construction. Photo / Waka Kotahi

“As the bridge crosses the North Island Main Trunk rail line, which includes a 25-kilovolt overhead line, the consequences of a bridge collapse are even more serious, and especially so if it occurred when a train was passing underneath.”

“We would remind the drivers of heavy vehicles that the six-tonne limit remains in place until the bridge closes,” Campbell says.

In an emergency, ambulance and police vehicles weighing less than six tonnes will still be able to use the bridge, as will light vehicles involved in the construction of the replacement bridge.

Hikuai River Bridge decked out for summer

Meanwhile, work has wrapped on the State Highway 25 Hikuai River Bridge deck replacement, just in time for the holidays.

Waka Kotahi Waikato system manager Cara Lauder said it was great to see the project completed ahead of the busy summer season, when traffic would increase significantly.

It's a wrap on the Hikuai River Bridge deck replacement. Photo / Waka Kotahi

“This has been a logistically challenging project, and a lot of planning and collaboration went into keeping the bridge open to traffic during the day while we carried out this essential work.

A new, sustainably-sourced and modular timber deck has been installed and sealed, along with upgraded road safety barriers, and the bridge is now open to all traffic.

Lauder said another important aspect of the project was working closely with emergency services to ensure they were across the closures and could be accommodated where possible.

“We erected a special scaffold walkway to be used by emergency services during the project, and this was utilised a number of times by the St John ambulance to transfer patients.

“Despite our best efforts, we acknowledge that any road closure is disruptive, so we are thankful to the community and road users for their understanding and patience during this time.”

Lauder said the bridge plays a key part in improving the resilience of the state highway network around the Coromandel region.