Blow, Wind! Come, Wrack! NZTA’s Flyover Planners Ought To Get The Sack

When William Shakespeare wrote the lines above, he was thinking of a certain unpopular Scottish king rather than NZTA (and to be fair, it was actually me who wrote the bit about NZTA).

But Wellington is a very windy place. We were reminded of that on Monday this week, when gusts of up to 140kmh rendered various Wellington streets unsafe. As usual, the wind speeds near the Basin Reserve were particularly high – in a strong north-westerly, Kent and Cambridge Terraces appear to act as wind tunnels, funnelling air towards the Basin Reserve.

And guess what NZTA want to build right in the path of such winds, and the less frequent but often equally vicious southerlies? A 9 metre high flyover, plus walkway/cycleway. 9 metres is a long way to fall.

NZTA’s own Basin “Bridge” proposal documents already admit that high winds will be a problem for the proposed flyover, as reported in this Dominion Post story:

A resource consent application for the proposed $90 million Basin Bridge, which was referred to a board of inquiry last week, states wind gusts in the middle of the bridge could be “extremely high”, at more than 25 metres a second, which NZTA confirmed amounted to 90kmh.

“The orientation of the bridge to the prevailing winds means that pedestrians and cyclists will be exposed to wind flows from the side, for which they are less prepared,” the consent says.

There is also risk to high-sided vehicles, such as lightly loaded trucks, and to motorcyclists when winds hit more than 90kmh: “Effects can range from causing tracking variations to complete overturning.”

Note that NZTA says the danger starts at winds of 90kmh – yet the wind reached speeds of 140kmh in Wellington in Monday’s storm, and similar speeds have been experienced in other recent storms. Wind gusts above 90kmh are by now means uncommon in Wellington.

The news gets worse for NZTA: Both the frequency and the strength of extreme wind events are expected to increase over the proposed project lifetime as a result of climate change (see, for example, http://www.niwa.co.nz/our-science/climate/information-and-resources/clivar/scenarios#regional). So the danger to drivers, passengers, walkers and cyclists will only get worse.

And what does NZTA propose to do about this serious and growing problem? Well, er … they plan to put up warning signs. Yep, that’s pretty much it.

The disconnect between the seriousness of the problem and the triviality of the response would be laughable if it were not for the fact that lives would be at stake if the flyover goes ahead. A wind of change needs to blow through NZTA: a strong wind, and soon.

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