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Aerial photo showing existing State Highway 1 under one of the new bridges being built for Transmission Gully

Transmission Gully building bridges

Progress on Transmission Gully construction on State Highway 1 (SH1) between Porirua and Linden is currently focused on building bridges.


CPB HEB JV Transmission Gully project director Justin Redelinghyus says the lifting and placement of bridge beams over SH1 commenced on the evening of Monday 11 March and is expected to be completed on Thursday 24 April.

“There are three bridges under construction in the area – the SH1 connection to Kenepuru Drive in Porirua, the northbound flyover connection onto Transmission Gully, and the middle section of the new bridge over Collins Avenue. We’ve already placed a set of bridge beams on one side of SH1, and this next phase is to lift and place the bridge beams directly over SH1 in the area.”

Each bridge beam weighs approximately 58 tonnes and there are 47 bridge beams to place in total. Two beams are lifted into place per night. A 350 tonne mobile (wheeled) crane and a 250 tonne crawler (tracked) crane are lifting the beams in tandem.

“The placement of the bridge beams requires precision and getting to this stage has required months of planning and scheduling. It’s important that we complete the job smoothly to maintain construction progress and limit disruption to the SH1 network,” adds Mr Redelinghyus.

Safety is paramount

CPB HEB JV Transmission Gully traffic manager Brian McInerney says safety of road users and staff is paramount to the project. “While the construction work is challenging, the management of traffic during construction is not without its own challenges.

“Running live traffic directly underneath a 58 tonne bridge beam while it’s being lifted by a crane is not something we would ever consider. To ensure the safety of road users and workers during this process, we will alter lane layouts to keep motorists well away from the beams on week nights from 7pm until 5.30am until this phase of work has been completed.”

The existing daytime traffic management layout with two lanes in each direction and a speed limit of 70 kph remains in place. “The area is starting to look and feel very different. It’s important that commuters and motorists drive to the posted speed limit of 70 kph during the day and refrain from slowing down to look at progress,” Mr McInerney says.

About Transmission Gully

Transmission Gully is a 27 km four-lane motorway which will run from Linden to Mackays Crossing, near Paekakariki, providing a high-quality safer alternative to the existing coastal highway. Built to demanding specifications, its design and construction reflect the need for a safer and more reliable route to Wellington for motorists, one that is more resilient to earthquakes and storms.

Four interchanges will connect the route to Mackays Crossing, State Highway 58, eastern Porirua, Kenepuru and Linden.

The Transmission Gully motorway is a key component of the 110 km Wellington Northern Corridor. Once complete, it will provide a safer, more reliable and more efficient motorway connection from Levin to Wellington, connecting the city to the growing economic centres of Kapiti and the Manawatu and the wider North Island.

The Transmission Gully motorway is scheduled to be open for traffic in 2020.


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