City's access, bypass routes must be split

KEITH RANKIN says the latest plan to ease central Auckland's motorway crush fails to get the diagnosis right.

Dialogue, NZ Herald, 10 Mar 2000

Auckland's latest traffic plan, approved recently by Transit New Zealand, proposes to expand Spaghetti Junction by, among other things, widening the Southern to North-western Motorway link, the Victoria Park flyover, and creating a Northern to North-western link.

The plan fails to address the root problem; indeed it aggravates it.

Auckland's traffic crisis is caused by the existence of a network of motorways that merge through- traffic with traffic going to or from the central business district. Spaghetti Junction is both a city-centre access route and a city-centre bypass route.

The consequence of this merging of two types of traffic is gridlock, which stunts the growth of the central city, promoting perimeter development instead. The consequence of perimeter development is that the nature of the journeys made by Aucklanders becomes increasingly complex.

Complex journeys, difficult to make via public transport, are almost always made by car. So the vicious cycle is that gridlock in central Auckland promotes increased use of the car through greater Auckland, which means that relatively more of the traffic using Spaghetti Junction is through-traffic.

The cycle can be broken only by separating through-traffic from city-centre traffic. Little can be achieved until the south-western State Highway 20 road-link is completed, enabling traffic from South Auckland to travel to Waitakere and North Harbour without going anywhere near Spaghetti Junction or the lower Harbour Bridge.

It's not enough to just complete SH20. We need to make sure that a large proportion of the traffic that uses the Southern-North-western motorway link, and the Victoria Park flyover will have an incentive to switch to the SH20 and upper harbour routes.

Making the Spaghetti Junction bypass links more attractive to motorists will diminish the incentive for them to use the western route when it becomes available.

There has been no decision on whether SH20 will be a motorway in its entirety or an arterial road in part The Green Party and many others who are opposed to further motorway construction are willing to support the completion of the south-western link as an arterial road. Such a road will be an attractive alternative to Spaghetti Junction only if Spaghetti Junction remains relatively unattractive to through-traffic.

If we are ever going to have a viable public transport system, Auckland will have to grow in a way that encourages more return-journeys to the city centre and fewer through-journeys. We will never achieve critical mass in public transport if Aucklanders in the main continue to want to make complex cross-town journeys that are difficult to make by bus, ferry or train.

Once we relieve gridlock by reducing the through- traffic that clogs central Auckland's arteries, we will be in a position to attract more people to central Auckland. Indeed, if we can get more cars to come into or near to the city centre, we create a potential market for public transport as an attractive substitute.

We are faced with two paradoxes: gridlock is causing traffic volumes to increase throughout greater Auckland; and encouraging more cars to go to the city centre is necessary to create a market for a user-convenient public transport system.

The car can be a complement as well as a substitute for buses, trains and ferries. By developing convenient park-and-ride facilities, all those complex shopping and child-chauffeuring journeys will still be able to be done, but without having to take the car anywhere near the central city.

Discouraging through-traffic from using the central-Auckland motorway system, while offering a reasonably attractive alternative route, could relieve the gridlock.

The Transit plan will do the opposite. It will attract more through-traffic into the centre of Auckland's roading network, thereby discouraging people from visiting the city centre, from seeking work in the city centre, or from setting up businesses in the city centre.

If there is little growth of travel to the heart of Auckland, there is no prospect of a viable public transport system.

Keith Rankin is an Auckland economist.