Ask Phoebe: Improvements for motorway - but no widening

With the fast-approaching completion of the new Manukau interchange with the airport/Southwestern Motorway, there will be a new injection of traffic on the southbound lanes of the already crowded Southern Motorway at peak times. Just 1.5km south of the new interchange the motorway narrows from three lanes to two at Hill Rd, and this is already a bottleneck. I assume widening of the motorway to at least Takanini is planned? Bill Bacon, Karaka.

While there are no immediate plans to widen the motorway between Hill Rd and Takanini, the NZ Transport Agency is working with the ARC and Auckland Regional Transport Authority, as well as the local councils, to come up with a long-term package of improvements for this area.

The SH20-SH1 Manukau Extension is on track for completion in August next year. It will provide a direct link from the Southern Motorway for airport traffic, as well as central and western suburbs via SH20.

Do you know if there are any plans to install traffic lights on the Papakura offramp heading south? With two new subdivisions under way in Karaka, not to mention parents dropping off and collecting children from nearby Strathallan College, the queues of traffic waiting to turn right are a nightmare. Catherine Taylor, South Auckland.

Again, it's a collaboration between the Transport Agency and Papakura District Council to improve things here.

The new interchange will have extra lanes for increased capacity. There will be dedicated onramps for both eastbound and westbound traffic, with traffic signals at the southbound on and offramp intersection with Beach Rd, and the northbound on and offramp intersection at Hingaia Rd.

Construction is set to start next year, and will take up to 24 months.

The widening of the Northern Motorway between Northcote and Wairau has greatly improved traffic flows, but it has moved the bottleneck further north. There seems almost enough room to add an extra lane from Constellation Drive to Greville Rd - is there a plan to do this? Rory Kernahan, Puhoi.

As I told you and other readers earlier this year, Mr Kernahan, there are no proposals to widen this stretch of motorway in the NZ Transport Agency 10-year state highway plan and forecast. However, in association with the North Shore City Council, the agency is reviewing the needs of this area.

What is the difference between a deviation (as in Hobsonville Deviation) and a bypass? Jim Watson, Auckland.

I consulted a roading engineer for this one. A bypass gives an alternative route, with the original one still freely available. An example is the bypass around Huntly. A deviation is the construction of a new road to be used in place of the old one, with the original closed off or for limited local use.

What are the thick blue lines about one metre out from the kerb that run both sides of Queen St and Albert St in the city? Ruth Barton, Auckland.

These are the lines that the public should stand behind during events such as the Farmers Santa Parade.