Ngā whakarākeitanga hoahoa matua – Key design refinements
View the general arrangement plans [PDF, 10 MB]
Whangaparāoa intersection design
We updated the Whangaparāoa intersection design to improve safety and traffic flow, as well as enhance stormwater management:
- On Whangaparāoa Road, we added another westbound lane after Cedar Terrace. This ensures future-proofed capacity for vehicles travelling from further up the peninsula.
- Only left turns in and out of Cedar Terrace to prevent unsafe right turns on and off Whangaparāoa Road.
- Extra lane length on Whangaparāoa Road for vehicles turning right to local roads.
Artist concept of the new Whangaparāoa Road / O Mahurangi – Penlink intersection.
Construction
People can continue to use Whangaparāoa Road during construction. The new road layout is being built next to it ‘offline.’ Some impacts are expected when transporting goods to site and later when connecting the new road to existing infrastructure.
Stormwater
Stormwater wetlands will capture and treat stormwater run-off from road surfaces. This reduces the risk of flooding in this low-lying area. Currently, flood waters overtop Whangaparāoa Road in a one in 10-year storm event. The new design will keep the intersection operating during a one in 100-year event. The wetland areas will feature ponds, landscaping and pathways.
Wēiti River Bridge
The Wēiti River Bridge is an extradosed bridge. An extradosed bridge is a hybrid between a box girder and cable-stayed bridge designs. It will be the first of its kind in Aotearoa New Zealand.
Indicative view of the Wēiti River Bridge, connecting Stillwater to Whangaparāoa.
Wēiti River Bridge design
The box girder element means it can carry a range of services and utilities, such as power and water, to the Whangaparāoa Peninsula. There’s even space for a future sewer main. The cables allow for a longer bridge span than the ‘balanced cantilever’ bridge in the project’s reference design. This reduces the number of piers needed to support the bridge and thus reduces the impact on the river below.
The span arrangement achieved with an extradosed bridge also enables the piers to be clear of the navigable waterway. Its position is more respectful of ecological and cultural site constraints.
We updated the Wēiti River Bridge design to deliver more benefits:
- Reducing the number of piers from three to two and removing the centre pier allows clearer views and passage through the navigation channel.
- Avoid cliff face excavation by removing the need for a pier on the eastern bank of the Wēiti River.
- Minimise greenhouse gas emission by improving construction methodologies.
- Reduce construction emissions by reducing materials
- Improve the overall amenity by lowering the entrance of the bridge so it fits better within the landscape.
Western temporary platform
Construction of the temporary platform on the western side of Wēiti River is underway. This platform will enable us to build the Wēiti Bridge. Noise will be heard on both sides of the river during this work. Works on the Whangaparāoa side of the river will be more noticeable to residents on the Peninsula.
