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Urban streets and other links

In my last post on urban densities I mentioned some research I didn't bother giving links for. In honor of a cool conversation two nights ago, let me get back to that!

Two related links on %age of city land devoted to streets and parking:

Chart in the first has columns for "built or buildable land", "streets and sidewalks" (so not just asphalt), "parks and plazas". Housing projects can be really low in built use, 10-27%; Cabrini Green had 44% streets and 29% parks. Actual cities listed start at 51% buildable and 44% rights of way, for both Savannah and Boston's Back Bay! Given Commonwealth boulevard, the latter isn't that surprising. Portland's at 47% streets, with almost no parkland. You actually get lower numbers with Phoenix -- I suspect wide streets but long blocks, whereas Chicago has decent sized streets and shorter blocks. NYC is 2/3 buildable, Paris 74% with 25% streets, and Tokyo 80% buildable with 20% streets (and no parks? wow.) Buenos Aires goes even further with 15% streets, but I've never been there.

So my model last time of 20% streets, 75% buildable, 5% parks seems like a nice place. And many US cities, even or especially the relatively pedestrian/transit ones, could in theory use only half the land they do for roads. The change to buildability is a smaller proportion but still significant, 40% to 60% more land use.

The second link has the blogger trying to estimate rights of way *plus* off-street parking; the first link was just "land devoted to roads", the second is "land devoted to cars." We start with 65% for Houston. DC is 44%... I guess almost all the parking in his sample area is curbside or underground? Anyway, it's just a few sample points, but at least some US cities put over 20% of their land to off-street parking. http://www.autolife.umd.umich.edu/Environment/E_Casestudy/E_casestudy2.htm provides some more numbers: 59% iin 1960 LA, 50% in 1953 Detroit.


Shoup talked about how parking requirements are based on imaginary numbers. Apparently the professional recommendations for how much land to put to roads is equally airy: http://www.citylab.com/cityfixer/2014/12/a-widely-used-planning-manual-tends-to-recommend-building-far-more-roads-than-needed/383759/

"Take an average school. Whereas the ITE manual predicts it will generate about 41 million trips a year, the 2009 household travel survey suggests the real trip number is closer to 13.7 million—overestimating traffic by 198 percent."


Cute picture of road chasms: http://www.vox.com/xpress/2014/11/18/7236471/cars-pedestrians-roads


Arguments for 20 mph speed limits

The deadliest US cities for pedestrians: http://www.vox.com/2014/4/18/5621388/pedestrian-and-biker-deaths


Bike lanes in NYC improved biker safety a lot and didn't slow down traffic: http://www.vox.com/2014/9/8/6121129/bike-lanes-traffic-new-york/in/5579561

See the comment count unavailable DW comments at http://mindstalk.dreamwidth.org/419310.html#comments



( 3 comments — Leave a comment )
Apr. 19th, 2015 10:49 pm (UTC)
Tokyo has several large green areas in the city limit - Imperial Palace and US Embassy grounds are two famous examples.
Apr. 19th, 2015 11:05 pm (UTC)
Ueno Park, Meiji Jingu... OTOH, what is says is "0%", could simply be that the park/plaza land was less than 0.5%, so rounds down to 0. Eyeballing the 23 wards... I don't know, I'd guess Chiyoda alone is about 1%, but I don't put a lot of stock in that, and I don't know what the blogger was counting as Tokyo. Zooming out doesn't show that much more green space within the Musashino line.
Apr. 19th, 2015 11:11 pm (UTC)
Reading the comments, the author says for complex cities like Paris he just sampled a representative-seeming area. So he might have done the same for Tokyo, and the numbers are actually "fabric" numbers, not counting big parks.
( 3 comments — Leave a comment )


Damien Sullivan

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