Sorting out the spaghetti to get traffic moving

By ARNOLD PICKMERE

Major construction work now started in the depths of Auckland's Spaghetti Junction will at last complete vital motorway-to-motorway links in the central city.

Fifty years after the first piece of Auckland motorway was begun, at Ellerslie, the city will finally have a cohesive system.

All the present main motorway arteries through the central city will be linked with each other and with the Port of Auckland. Completion date is June 2006.

The junction is getting its biggest improvement since 1978, the year the Southern Motorway was linked directly with the Auckland Harbour Bridge.

Described by Transit NZ as the biggest roading project in Auckland's history the "Central Motorway Junction Project Stage 2" is costing $140.4 million. It will include more than 750m of new viaducts and bridges and more than 2km of new retaining walls. About 80,000 tonnes of asphalt will be laid on existing and new highways.

THE PRESENT WORK WILL ALLOW

* Southbound traffic from the Northern Motorway (SH1) and Harbour Bridge to connect directly with the Northwestern Motorway (SH16) westbound and West Auckland. (Possible opening, autumn 2006.)

* There will also be a direct southbound connection from the North Shore down Grafton Gully to the Port of Auckland. (Possible opening, autumn 2006.)

* Other connections include a direct motorway link between the Northwestern Motorway eastbound and the harbour bridge and North Shore. (Possible opening, late next year.)

* And a direct link from the port and Grafton Gully to the North Shore. (Possible opening, summer next year.)

The project is already employing up to 250 people on site. It also involves improvements to on-ramps and off-ramps and a better connection for northbound motorists leaving the Southern Motorway for the Northwestern.

(Central Motorway Junction Stage 1, also now in progress, involves the present $54.95 million of widening and other work between Khyber Pass and Gillies Ave. And changing the 204m-long Khyber Pass Viaduct from a double structure to a single, much stronger one. It is due to be finished in December next year.)

By the time the Stage 2 project is finished just about every bit of space in the designated central Auckland Motorway corridor will be covered by the road network.

Back in the 1970s the work establishing the network of roads through Spaghetti Junction was described as complicated but essential. There were then about 72,500 vehicles a day travelling on the Gillies Ave-Khyber Pass section of motorway (the busiest in the country).

But the engineers on the present project have had to design a new maze of lanes to snake between, under or over the existing network in the same designated corridor. And all within strict safety standards which include motorists' sight lines, gradients and height clearances. Safety barriers are being upgraded and the changes will require revised signage.

In the 1970s the engineers started with a blank slate. But all the present work has to be carried out without seriously affecting the 200,000 vehicles a day that flow through the junction's busiest part.

EFFECTS OF NEW LINKS

These are expected to include:

* Better traffic flows

Transit says the new links will provide more direct connections, improve the vehicle handling capacity of the central city motorway junctions and improve the system's overall efficiency .

* Less traffic on inner-city streets

Traffic on inner-city streets and at interchanges will be reduced - in particular Nelson St, Hobson St, Union St, Pitt St and Wellington St.

These streets are now involved with handling traffic from the Southern and Northwestern Motorway off-ramps into Nelson St, and the present Northwestern to Northern link by way of the awkward Union St connection to the Wellington St on-ramp at Freemans Bay.

A good percentage of the Northwestern traffic which now often jams the Nelson St off-ramp to use this route to the North Shore will in future stay on the Northwestern Motorway and simply drive straight into the Northern (possibly by late 2005).

* Less heavy-vehicle traffic

About 320 heavy vehicles a day at present travel through inner-city streets from the Northern Motorway to the port.

Possibly as early as autumn of 2006 they will have a direct motorway route.

* Smoother connection

In future there will be two motorway lanes each way north and south for people travelling straight through the central city. This traffic will have no need to drive on city streets.

To improve traffic flow and safety in these lanes there will be a new Southern Motorway-to-Nelson St northbound off-ramp.

It will allow city-bound traffic to exit on the left-hand side of the motorway, instead of weaving across to the right-hand exit now in use. The present off-ramp will be used only for emergency services and service vehicles.