Transport was my round when I worked for Twyford and earlier for Genter.

So, I had a look at National's '$1.5b' expressway to Ashburton that they announced to universal yawns this week.

First off - they've got the costing way, way under....

... If you look at 4 lane expressway we've built recently/are building- the cost is $30-35m a kilometre (that's over $30,000 a metre - these things are beasts - new corridors need to be bought, huge road beds & works). Ashburton-Chch would 60km of new 4 lanes- so ~$2b but wait...

... this expressway would include 3 major bridges including crossing the Rakaia. at 1.7km - the current bridge is the longest in the country. How much does a long bridge cost? based on the new Manawatu Bridge, about $100m/km for 2 lanes. So, $170m for 2 more lanes Rakaia alone...

let's conservatively say a quarter of a billion for new bridges. Now ~$2.25b total, 50% more than the Nats have budgeted. And, in reality, these projects always overshoot

So, how many vehicles are using this road? about 11,000 (total for both directions). that's not many...

... that works out to <10 vehicles a minute each way for most of the day, which means plenty of space for vehicles at 100km.

At this traffic level, NZTA's ideal is a 2 lane road w frequent passing lanes.

It's a third less traffic than the currently planned expressways get...

... a 4 lane expressway would be able more than 3 times the traffic that Ashburton-Chch gets.

This huge, mostly empty road carrying a few hundred vehicles an hour, would cost more than the govt spends in 3 years on all public transport, which is over 500 million trips...

... it's lazy thinking from the Nats. They say they're about value for money - well value for money here would be more passing spots and fixing black spots for a fraction of the cost.

That's what NZTA is actually planning and what the locals want...

... during their recent public engagement, NZTA said some people at Ashburton wanted an expressway but it wasn't on the radar for people on the rest of the route - most people everywhere want realistic fixes soon, not some giant road that would take 10-15 years to build ...

... apart from the fact National has no way to fund this project, it would be far more sensible to spend a few hundred million upgrading capacity of the existing route and making it safer, and spending the other 2 billion on urban public transport...

... you would move more people, cut more congestion, help more businesses, and reduce emissions.

plus, politically, you would actually win some voters. Over $2b on a road that only a few people in a of 35,000 that already votes heavily National care about? weird politics...

...this National fantasy is to far fetched it's not even in NZTA's 'one day' pile.

The enormous cost for relatively few vehicles just doesn't add up. A party claiming fiscal responsibility would never propose it.

But National's religious obsession with roads trumps commonsense.