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HCoFP: checking parking lot size myself

Shoup keeps using "130 spaces per acre, 30 meters per car" as a figure for parking lots. This seemed like a lot, so I did a spot check. My apartment has a parking lot, with 23 parking spaces (plus a van stuck in a corner, but it can't get out at the moment.) Google Earth says the lot is about 27x27 meters. This comes out to 31.7 square meters per car. Ding!

I don't know if the space could be used more efficiently. It's a square with all the spaces on the sides, so it looks like there's a huge empty middle, but cars need space to back up and turn around. Even if you squeezed in 4 more spaces, that would drop it down to 27 m2/car, not a huge difference. And I doubt you could, though you might be able to put 2 in the middle, still 29 m2/space.

The actual spaces seem to be 5x2.8 meters, +/- .1 on both measurements; 14 m2, or 322 m2 for the 23 spaces, out of 729 (27*27). 44% usage, 56% overhead in corners, driveway, and maneuvering room.

A stretch of street is 8 meters wide and 26 long, with 10 curbside spaces (5 on each side) and a one-lane road in the middle. That's somewhat more efficient, only 21 m2 per parking space, instead of 30. Measurement on another street finds 8x17, and 6 cars, for 23 m2/space.

For Mass. Ave, a boulevard with 2-3 lanes each way and a 2 meter divider, I get 22.5 m across, and in a 12 m long stretch, 4 spaces (2 on each side.) 67.5 m2 road/space.

For the Porter Square 'mall', the main rectangle is 137.5 m long and 61 m wide. I could 268 parking spaces but there may be some errors. It comes out to... 31.29 m2 per space. 279 spaces would still leave 30 m2 per space, so even if I missed a lot due to trees the figure still holds. And unlike my apartment lot, the space looks used fairly efficiently.

So yep, I believe it now: 30+ m2 per parking space in a lot. Down to maybe 21 for one-land double-curbside streets.

What's the raw value of land? I'm not sure, but looking at Zillow, empty lots in Boston seem to be $200-1399 /m2; no lots in Cambridge, but dividing home prices by their lots gives $1500-2000/m2. That's high, because I'm including the value of the actual home, OTOH with expensive land how much of the price can be the home? At any rate, we get the value of 30 m2 being $6000-$60,000. A more narrow range would be $15,000-$30,000 per parking space, at least around me.

Or: from the city's POV, the cost is the foregone property taxes on fully developed property. Which puts us back to high value. $60,000, 2% property tax rate, $1200/year, $100/month... residential parking permits are $25/year. And that's just one parking space; you need another one at work to park your car if you drive to work, and at least a fraction of another one amortized around various businesses or schools. So free parking = $2400-$4800/year of subsidy. A curbside space is $500/year.

For places not as built up as Cambridge the subsidy will be less, in a sense, though arguably the opportunity cost is not being more like Cambridge. Even dividing by 10 puts us at $240/year at the low end, and that'd be a place where condos go for $50,000 and homes for $90,000.

See the comment count unavailable DW comments at http://mindstalk.dreamwidth.org/353406.html#comments



( 2 comments — Leave a comment )
Mar. 3rd, 2013 02:25 pm (UTC)
In addition to the land cost, there is the annual maintenance. A quick google shows it is another $100 - $300 per year per parking space for snow removal alone.


It might be cheaper to offer free public transit in the downtown core than to have parking.
Mar. 3rd, 2013 02:37 pm (UTC)
Ooh, interesting addendum, thanks!
( 2 comments — Leave a comment )


Damien Sullivan

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