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Three lanes into two for the new Buckle Street tunnel?

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by Elaine Engman
Most Wellingtonians rightly believe that the Basin Reserve flyover will be a very expensive eyesore. Some have accepted it with the idea that it will improve traffic flows. But after a careful examination of the Transport Agency’s working plans, it seems obvious that the flyover will not improve overall traffic flows, but will more likely make rush hour traffic worse and cause more accidents.

The plans show that the new Buckle Street tunnel will have only two lanes which will carry the two lanes of west-bound traffic from the proposed flyover. However there will be a lot of other traffic coming into the tunnel, from Kent Terrace, Mt Cook and most importantly from Adelaide Road. To accommodate this additional traffic, a short “slip lane” will be in place. But this extra traffic will have less than a hundred meters to integrate into the two lanes of vehicles from the flyover.

Traffic jams are caused when the number of motorway lanes are reduced. The Transport Agency is very fond of these “pinch points. Some local examples: the Mount Victoria Tunnel, which is mainly responsible for traffic pressures around the Basin Reserve; the Terrace Tunnel coming into Wellington from the north; and where State Highway 1 narrows from two lanes to one lane between Plimmerton and Pukerua Bay going north. This last example has the worst daily rush hour congestion of any part of SH1 heading to Waikanae – much worse than the road between Paraparaumu and Waikanae.

The new tunnel under Buckle Street should improve traffic flows since one traffic signal will be eliminated. But there will undoubtedly be traffic backup through the tunnel during rush hour. And if the flyover is built, the short merge will not only create another “pinch point” but also will be likely to cause accidents. Motorists on the new flyover will be inclined to drive at more than 50 kph, speeding into the tunnel and conflicting with the other traffic attempting to merge into the two lanes.

There is to be no ventilation in the new tunnel. Drivers backed up into the tunnel by the Taranaki Street traffic lights will need to keep their car windows and vents closed unless they particularly enjoy the smell of auto and diesel fumes. For this, taxpayers will pay $90 million.