KEY POINTS:
The discovery that trucks have been told not to use the outermost lanes of the Auckland Harbour Bridge is a reminder of the vulnerability of this most crucial point in the city's, indeed the country's, main artery. Many bridges on State Highway 1 may be older and farther
from alternative routes, but none would carry anything comparable to its volume of daily traffic.
It needs to be noted that the bridge is not an imminent risk. Transit NZ says it has issued the instruction to trucks to reduce stress on the "clip-ons" added to the bridge in 1969 and extend their expected life of 50 years. But with only 12 years left of that original estimate, and remembering the main structure is 10 years older, it seems time to consider another crossing seriously.
The subject comes under discussion periodically but never with much urgency. The national and regional transport authorities have seen more pressing needs at other points, notably the Grafton Gully connections to the port, the new strands at Spaghetti Junction, the northern busway and the motorway extension tunnel to Puhoi. Next on their list are a second harbour bridge at Mangere, widening the Victoria Park flyover, completing the western ring and, Cabinet permitting, electrification of the western railway.
As North Shore commuters can confirm, the Harbour Bridge is not a serious congestion point. Worse bottlenecks occur at Victoria Park and at entry points to the motorway. Traffic on the bridge usually flows quite well. Plans for a parallel harbour crossing remain nothing more than conceptual for Transit and regional planners. Transit has done a "constructability" study of options which favours either a bridge 500m to the west of the existing structure or an underwater tunnel to its east. Objections from Northcote Pt led the Auckland Regional Council to commission a review, which favoured a duplicate bridge alongside the present one on its eastern side. It warned that a tunnel might not be feasible once the waterfront is developed from the Viaduct Harbour to the western reclamation.
A tunnel must not be ruled out on that account. A tunnel is the only visually acceptable second crossing of the wide Waitemata. The bridge across the upper harbour, which is being widened for the western ring, is fortunately out of sight from most views of Auckland. But a second bridge within sight of the first would destroy one of the city's most scenic qualities - an expansive inlet crossed by a single arch.
A tunnel from Northcote Pt to the western reclamation would be much preferable, and feasible. A proposal for just such a tube on the harbour floor was put forward by McConnell Dowell some years ago. Since then the Viaduct has been developed and the city council is planning to improve the waterfront west to, eventually, the site of the present tank farm.
Whatever landmark may be built on that site it need not preclude a tunnel entrance in the vicinity. If the tunnel needs to be extended farther inland to enable the western reclamation to become a pleasant public space, so be it. The cost of a tunnel would be considerably more than a bridge in any case and tolls are probably inescapable, as they were for the existing bridge. To ensure no one crossing the harbour escaped the toll, the bridge might need to be tolled as well, which was the McConnell Dowell proposal. But a bridge toll might not be necessary if the bridge ramps to the inner city were sealed and the tunnel became the only access from North Shore to the central business district.
With the closure of the outside lanes to heavy vehicles, the bridge's mortality becomes evident. It is time to consider alternatives, seriously.