Is Kapiti Coast SH1 Quake Proof?


A Wellington group is today asking whether SH1 needs to be moved in case earthquake-hit residents in the capital can’t escape north - especially in relation to the proposed motorway is built up the coast.

Colin Baxter of the Save Kapiti group says he was so concerned by the Japanese tsunami story, he mocked up SH-1 (Eastern) and Kapiti expressway (Western) on to a GWRC earthquake map in light of NZTA assurances the new expressway will not be in danger of stopping motorists fleeing.


SH-1 (Eastern) in on moderate risk land (yellow) but that proposed new Expressway (Western) is on mod to high risk land (dark yellow).

He tells AKT:

“I suspect this is a liquefaction issue with it being sand and wetlands etc. I also marvel at our predecessors who chose the eastern route without today’s knowledge and high tech gadgets. But then the wetland would have been obvious to them at that time.

One key fact is that this new route will require numerous (10+) fly-overs which the WLR will not. This is picture-2 Each of these is at risk of collapse and will block escape routes.

“This puts to the sword NZTA’s previous comment about climbing to the top of the bridge to be safely away from the Tsunami.

“Again did NZTA know this information and not release it during consultation phase 1 (Oct 2009) or phase 2 (Feb 2011)?

“NZTA also need to state what size earthquake they propose to engineer each of the fly-overs (and ramps) to withstand. This will add to the cost and delay the timing.

“I also have found a picture of an expressway which collapsed in Japan recently.

“Note also the bend in the expressway (NZTA maps straighten this out) - this ties in with a GWRC statement that the expressway is 1.5 kms longer that SH-1 (eastern) upgraded (straightened).”

It’ll be interesting to see the feedback.




  1. Andrew says:

    Slight technical correction: that collapsed freeway is from the 1995 Kobe quake, so not really “recently”. Otherwise, an interesting point.

  2. Kegan says:

    Using that photo is scaremongering. No motorway/expressway viaducts of that scale are planned. Also, that was not exactly a modern design at the time that it happened - similar in age and design to the Thorndon Motorway Viaduct (which has since been strengthened).


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