A couple of Texas Monthly articles on stack interchanges

[kurumi]

Other articles from this magazine (frontage roads, etc.) have appeared in the forum, but as far as I can tell, these have not:

https://www.texasmonthly.com/being-texan/the-texanist-tall-overpasses/

Q: I recently drove down from Iowa to see my daughter in Austin, and during my visit I couldn't understand why Texas has so many highway overpasses and why they were built so insanely high off the ground.

(There's probably a similar culture shock when a Texan travels to Minneapolis and, like Buzz Lightyear, exclaims "Cloverleafs... Cloverleafs everywhere.")

https://www.texasmonthly.com/politics/highway-interchange-houston-same-size-city-italy/

In his Twitter post, Michael Hendrix of the Manhattan Institute, a free-market think tank, pointed out that the city center of Siena, Italy, packs roughly 30,000 residents into a space roughly the same size as one of Houston's countless stack interchanges. Hendrix pulled this eye-opening comparison from a report compiled by the U.K.'s Building Better, Building Beautiful Commission, which sternly suggests that housing 30,000 Italians is less wasteful and more sustainable than using the same amount of acreage to simply move cars around.

[texaskdog]

having moved from MN to TX I learned to really hate cloverleafs, don't miss them at all.

[bwana39]

There is plenty of head space between each layer of the stack.  There are not a whole lot of ice days in Texas. While they stop the whole world, flyovers are little worse than the surface streets in terms of icing. A flyover might have a 55 MPH limit: a cloverleaf (corkscrew) likely would have one at 30 mph or less.

[Chris]

The comparison to Siena is misleading. The picture shows approximately 1.5 km² of dense Siena, and compare it to Houston's interchange, which occupies about 0.4 km². Yes Siena has a dense core but it's not the exact same thing, with Siena's urban core being almost 4 times larger than the Houston interchange. They also don't tell you that the other half of Siena lives in a much lower density, the urbanized area occupies approximately 25 km² leading to an average population density of 2,000 per km² (similar to U.S. suburban areas). The whole municipality has a density of only 450 per km².

Siena is also a small city, with an overall population of 52,000 so it doesn't need a huge road system for internal transport. It also has a declining population, typical of many urban cores in Italy that are overcrowded with tourists (Venice has lost a huge chunk of its population as it has become an unlivable open-air museum).

A typical misunderstanding of American urbanists is the thinking that higher density = less car ownership. Italy has a lot of high density cities but its car ownership is actually one of the highest in Europe. But they drive a Fiat 500 instead of a pickup truck or SUV. According to Statista only 6% of Italian households do not own a car.

[kphoger]

A typical misunderstanding of American urbanists is the thinking that higher density = less car ownership. Italy has a lot of high density cities but its car ownership is actually one of the highest in Europe. But they drive a Fiat 500 instead of a pickup truck or SUV. According to Statista only 6% of Italian households do not own a car.

Is that lower than the USA?  Numbers I'm seeing for US households are in the 7%—9% range, depending on the year.