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Phoebe Falconer answers your questions about Auckland

Ask Phoebe: Southbound connection of SH18 with SH1 just hasn't got traction

By Phoebe Falconer

Looking South along the new SH16 Brigham Creek Extension and SH18 Hobsonville Deviation interchange. Photo / NZME.
Looking South along the new SH16 Brigham Creek Extension and SH18 Hobsonville Deviation interchange. Photo / NZME.

With regards to the Northern Corridor Improvements project, I see that the main reason is to provide an alternative north-south connection around the city. But is there any reason the southbound connection of SH18 with SH1 has not been included? It seems a lot of effort is being made to connect SH18 and SH1, but it seems strange that the southbound connections to SH1 are missing. The southbound connections would complete the ring route around north and west Auckland. Andre van Zyl, Auckland.

The Northern Corridor Improvements project is part of the Government's accelerated programme, with one of the key components of the project the provision of a motorway-to-motorway connection at the SH18 to SH1 end of the Western Ring Route. This connection will help to better facilitate the west to north and north to west movements between SH18 and SH1 and promote the alternative to SH1. The Transport Agency has thoroughly investigated the design options for providing direct southbound connections between SH18 and SH1 and vice-versa.

However there is not currently enough capacity south of Constellation Drive on SH1 to take additional traffic which would be generated by a southbound connection. Until capacity is increased on SH1 further south towards the Harbour Bridge, adding these connections now would create bottlenecks and reduce efficiency on SH1. The Transport Agency designs for the Northern Corridor Improvements include future-proofing the areas required if links were to be built at a later stage. In the meantime West Auckland commuters who continue to use the Constellation Interchange can expect better journey times. Traffic modelling shows that changes to traffic flows and traffic light priority will improve flows at the offramp and intersection.

Yours is the second reference I have seen in the Herald last month to Auckland's "Southeastern Motorway". There is no Southeastern Motorway: it is a highway. Are there plans for the Southeastern Highway to become a motorway? Jeremy Ashford, Auckland.

Correct. It is the Southeastern Highway, not motorway. The error was mine.

Motorways are access-controlled, high-speed roads that normally have "grade-separated intersections" which means they have overbridges (or underpasses) so road users don't have to stop at traffic lights.

To put this into context: the term "state highway" differentiates between local roads, built and maintained by local authorities, and the national state highway network. "State", in the sense used here, is an older term meaning "government". State highways are those roads that form a nationally strategic purpose in moving people and goods nationwide.

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- NZ Herald

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