9-line access access management access point accessibility ADA air quality alignment amenity antiplanner atlanta BART benchmark BID bike Blogs boston branded bus corridors brookings brt bus Bus Rapid Transit BYU capacity car pool car pool lane cars central link Centrality certification commuter rail condo congestion congestion pricing connections consistency coverage crossings CRT cycling DART dedicated dedicated right of way density denver depreciation developers development economics efficiency Envision Utah equity eugene exclusive extension FAQ favela Federal Funding Flex Bus florida free fare zone freeways frequent network frontrunner frontunner Gallivan garden cities gas prices geotagging goat Google grade-separation Granary District growth headway heavy rail hedonic High Speed Rail history housing housing affordability housing bubble housing prices HOV income infill innovative intersections intensity ITS junk science LA land use Land Value Economics LEED legacy city light rail linear park location LRT lyft M/ART malls mapping maps metrics metro MetroRail missoula mixed mixed traffic mixed-traffic mobile mode choice Mode Share multi-family MXD neighborhood networks news NIMBY office online op-ed open letter Operations parking parking meters peak travel pedestrian environment phasing Photomorphing planning Portland property property values Provo proximity quality_transit rail railvolution rant rapid rapid transit RDA real estate redevelopment reliability research retail Ridership ridesharing right of way roadway network ROW salt lake city san diego schedule schedule span seattle separated service branding shuttle silver line single family SLC SLC transit master plan slums smartphone snow sprawl standing stop spacing streetcar streetscape streetscaping subdivision Sugarhouse Sugarhouse Streetcar Tacoma taxi technology tenure termini time-separation TOD townhouse traffic signal tram transit transit agency transit networks transit oriented development Transit Planning transponder transportation travel time TRAX trip planning trolley tunnel uber university of utah urban design urban land UTA UTA 2 Go Trip Planner utah Utah County Utah Transit Authority value vmt walking distance web welfare transit Westside Connector WFRC wheelchairs zoning

Tuesday, March 1, 2011

Low Rise, High Density

Looking at images of Paris and New York's Lower East Side, I realize that very dense, older urban areas are not particularly high rise. In many cases, they fail to exceed 4-5 stories. But I would estimate a Floor Area Ratio of something like 400%, which generates transit suitable densities. What is critical in generating sufficient density for transit appears not to be tall buildings, but the lack of parking. Every car takes up 300 square feet per parking stall. Include landscaping and access lanes, that means 10 acres of land only provides about 900 parking spaces. Keeping that same ratio, a 1 acre parcel could be used to produce 90 surface parking lots. Or (at 350 ft^2) about 125 small offices. But if each office is matched to a parking stall, so the net production is about 62 offices.

Structure parking is enormously expensive, because it has to support a 'live load' of cars, rather than people. Thus, as much as possible of the need for parking will be met using surface lots. Assuming a 1:1 office:parking ratio, 2 stories of office mean that 2/3 of the parcel must be devoted to surface parking. With a four story building, 80% of the lot will need to be devoted to parking. Automotive oriented high density will produce a city of vast towers, islands in a sea of parking--hardly urban.

Thus, generating urbanism is not just a matter of generating density--it is a matter of providing density without providing parking. Which means alternative modes of access.