Pier four ready for concrete pour for the columns

On site update

All seven piers are now being built and they’re at a variety of different stages- some are ready for the concrete to be poured or the cofferdam to be removed, while others are some way off being complete.

The second large pier (pier three) which will hold up the architectural arch along with pier two has had its four columns constructed and the team is now working on installing the deck connectors. These will connect the inner columns of two of the large ‘V’ piers to the deck so that the structure is secure.

We’re currently transferring the sheet piles and cofferdam frame from pier seven to where the southern abutment will be so we can start to work on this element of the new bridge. The northern abutment was completed earlier in the year.

The base for the new bridge deck is also well underway, with a total of 21 beams installed between the northern abutment and pier two which means that three spans out of 10 are now complete.

Photo showing cofferdam (left), deconstructed old bridge (centre) and temporary staging (right)

Deconstruction of the Old Māngere Bridge reaches halfway mark

Deconstruction of the old bridge has re-started and in mid-July we reached the halfway mark. The bridge will be fully removed by the end of the year.

The temporary working platform which we're building for deconstruction has also extended with four new spans installed. In September, this temporary working platform will be closer to the boat ramp at the end of Coronation Road. While access to the boat ramp will be maintained, there’ll be less space than usual between the end of the boat ramp to where our temporary platform starts. It’ll be like this for about a month and we ask users to please take extra care when navigating around the area.

Don’t forget to check out the notice board with some helpful user guidelines before you head into the water so everyone can stay safe whilst enjoying the Manukau Harbour.

Image of a hydrophone (equipment in black) connected to rope with a weight to sit on the seabed and the buoy will be floating in the water

Protecting marine mammals in the Manukau Harbour

The Manukau Harbour is home to some of New Zealand most important marine mammals such as Fur Seal (Kekeno), Orca (Maki), Common Dolphin (Aihe) and Māui dolphin.

Some species like the Māui dolphin have significantly reduced in number with less than 100 left making them one of the rarest in the world. It’s really important to our team that we keep the marine mammals safe from construction noise and vibration effects while we’re working within the harbour. To help with this, we developed a plan to manage the effects of our construction activities such as seabed piling and deconstruction of the old bridge.

To help us understand how much noise and vibration we could cause and ensure we stayed within our allowed limits, acoustic specialists conducted underwater noise monitoring by putting a hydrophone in the Manukau Harbour. A hydrophone is an underwater microphone attached to the rope of a sub-surface buoy which is weighed down, so it sits on the sea floor (see above image). These were left in the water for several days while our team undertook several construction activities before it was collected so we could analyse the captured data.

As a result of the information gathered, we’re using a variety of different methods to try and reduce the possible impact on marine mammals such as machinery that generates lower levels of noise, gradually increasing the intensity of vibration piling as well as having a spotter before and during work in case any curious mammals come and check out what we’re up to. The spotter ensures that no mammals swim within 50 metres of the work site and if they do, we down tools and stop till they swim away.

Connecting communities

For more information on the Old Māngere Bridge replacement project, freephone 0508 623 266 or contact us at omb@nzta.govt.nz

Or visit our website https://www.nzta.govt.nz/projects/old-mangere-bridge-replacement-project