The debate about the proposed multibillion-dollar eastern highway has benefited from the thoughtful contributions by Papakura District Mayor David Buist and Graeme Scott, of the Institute of Architects.
Both noted the urgent need to complete the southwestern (State Highway 20) motorway from Manukau City to Rosebank Rd. One well-designed bypass route is needed, not John Banks' vision of a grandiose triple bypass.
By and large, however, the debate continues to be an unproductive stand-off between the advocates of car-based solutions and the advocates of public transport. This stand-off is predicated on the supposition that Auckland's gridlock is little more than a commuter management problem.
Neither David Buist's nor Graeme Scott's articles mentioned the word "truck". Yet a viable road network must cater to commercial vehicle use as well as to commuters.
It's not about whether more motorways are better or worse than less motorways. It is about looking at the whole of Greater Auckland, and designing with least financial and environmental cost a road and rail network that fits Auckland's geography.
A second eastern highway makes no sense in a city with its economic heartbeat along the southwestern corridor, and where the obvious areas for industrial-commercial expansion are west of State Highway 1.
The transport network - private and public - needs coherent rather than piecemeal design, and a focus on completing projects that have been started. It also requires an appreciation that the built environment of Auckland will be shaped, for better or worse, by its road and rail networks.
Good design of a city's transport networks requires an understanding of the transport markets involved, the various third-party costs, and an awareness of the scope for substitution from one transport mode to another.
The commuter market is just one of four transport markets. Spaghetti Junction, by separating the city centre from the rest of the city, has made central Auckland an unattractive place to locate a business. Thus the city's gridlock, which is created by traffic bypassing the city centre, has further encouraged businesses to bypass the central city.
The solution to this problem is not a new motorway into the city centre. Rather, it is to complete the existing half-built motorway that will allow through-traffic to steer well clear of the city centre.
All commuter traffic that passes through Spaghetti Junction (for example, from north and west to destinations south or east of the city centre) carries huge third-party costs for Auckland as a whole, and for the central city in particular.
The classic economic remedy for such "negative externalities" is a tax. Certainly, once the SH20 motorway is completed, it should be paid for in part by electronic tolls, not on SH20 but on the western (SH16) and northern (SH1) bypass links of Spaghetti Junction.
The most important market for private transport in Auckland is the business market. The SH20 route already substantially reflects Auckland's industrial corridor. Once completed, the SH20-SH18 semi-orbital route will define Auckland's blue-collar heartland.
Starting at Silverdale in the north, the industrial corridor of the future will link to Albany, and to Hobsonville and Whenuapai via SH18. Whenuapai will, in turn, connect with Henderson, Avondale, New Lynn, Mt Roskill, Onehunga, Mangere, Puhinui, Manukau and Papakura. From Onehunga, the industrial corridor branches to Penrose, Southdown and Mt Wellington through the southeastern arterial.
A third market of transport users is education. It is often noted that the morning rush hour vanishes during the school holidays. Many conclude, therefore, that Auckland's traffic problem would go away if more students used public transport and attended schools closer to where they live.
The main reason for the school holiday effect, however, is that many parents take annual leave during the school holidays. It is the drop in commuter demand, not in student demand, that makes the bigger difference.
The final key market for Auckland transport is the port. Most other maritime cities have modern container facilities well away from the city centre. Auckland's port, however, is fated to continue to be based in the central city, and with an eastern orientation.
The solution is to build a "portway", rather than a six-lane motorway, along the present rail corridor. To minimise environmental costs, the existing eastern route from seaport to SH1 at Westfield is viable as a two-lane truckway/busway/railway. A single rail track will suffice.
A link to the yet-to-be-built North Shore busway would give a high-speed bus route from Albany through to Botany town centre, via Britomart. From container port to Panmure, this busway would double as a truckway.
Operating the eastern highway both as a commuter busway and a commercial truckway would free the Britomart rail terminus to take high-volume commuter rail traffic from the west and south, including suggested new rail links to Manukau City Centre and Auckland Airport via Onehunga and Mangere.
By 2020, if we get smart, there could even be a direct rail link between Auckland International Airport, Mt Roskill and Auckland's growing northwest.
Indeed, we should be encouraging people to make more of the kinds of road journeys that will eventually be able to be substituted for journeys by train or high-speed bus.
Completion of motorways today creates tomorrow's demand for public transport.
* Keith Rankin teaches economics and statistics at Unitec.