KEY POINTS:
This week, Transit New Zealand launches a $50 million ramp metering system in a bid to squeeze yet more vehicles onto Auckland's clogged motorway system.
The road boffins have adopted the old chef's trick that if you drizzle a new ingredient into the mix rather than pour it all in at once, you won't end up with lumps. That's the theory anyway.
But when 186,000 more cars are off-loaded at Ports of Auckland each year, it's hard to believe that it will make much difference whether you ease them into the road arteries or just drop the green flag and say go.
Riding to work in the bus last week, looking out on the long stream of cars backed up Curran St and along Jervois Rd waiting to get on to the harbour bridge, it seemed blindingly obvious that the solution to motorway congestion lay not in trying to find new ways of squeezing more people onto them. The answer was to entice as many drivers as possible to exit the system at the first signs the arterial system is beginning to seize up.
A ten-minute bus ride was not long enough time to perfect every last detail of this traffic engineering breakthrough, but here's the guts of it. Welcome to Ramp Rewards, where motorists are encouraged by flashing overhead signals - and rewards - to decongest the motorways by exiting from the closest ramp.
Sound loopy? Well, surely no more so than the latest proposal, which rations access onto the motorway, but threatens to create chaos in its wake. That's if the trials at Mangere are any guide. There, say the locals, suburban roads have become clogged as would-be motorway users queue back into surrounding suburbia.
Transit's media releases sound as chipper as a medical salesman announcing the latest breakthrough in heart pacemakers.
There are to be cameras and other vehicle detection systems to monitor traffic flows on the motorways and waiting times at on-ramps. All of this linked back to a central command module just north of the harbour bridge. All state-of-the-art, we're assured - though given the price tag, one would be rather upset if they were not.
By August next year, 31 Southern Motorway on-ramps from Curran St, Herne Bay, south to Papakura will be in the system. Ten will be operating by this Christmas, all drizzling cars slowly enough into the network that, theoretically at least, they don't interfere with the existing arterial flow. That's the prayer anyway.
But even if ramp metering (or ramp signalling as the boffins call it) were to succeed in squeezing a few more cars into the system, it's at best an expensive one-off victory, doomed to defeat by its own success. After all, how many extra cars a year can we decant into the mix, however scientifically we do it?
Which takes us back to the alternative, that is persuading drivers to voluntarily declog the motorway at times of stress.
The favoured tool of the political right - and of truckers and others who don't have to pay the bill out of their own pockets - is road tolling or congestion tax or a mix of both. This would not only provide funds for more motorway building, but would also price the poor and their secondhand imports off the network. Unsurprisingly, it's not very popular.
Transit is consulting Aucklanders over its plans to introduce tolling to help accelerate the building of the long-overdue western ring route. The Automobile Association recently joined the region's local bodies in opposing such a scheme, which leaves Transit in an increasingly lonely position.
Which takes us back to the carrot of Ramp Rewards.
With all the fibre optic cabling and camera systems already organised for ramp signalling, to say nothing of the camera networks being discussed for tolling, it surely wouldn't be any more difficult to wire up a rewards system instead. Transit could send drivers petrol tokens instead of bills.
Where would the money come from? Well, how about the savings from not having to build so many new motorways?
