Labels

9-line access access management access point accessibility ADA air quality alignment amenity antiplanner atlanta BART BID bike Blogs boston branded bus branded buses brookings brt bus Bus Rapid Transit BYU capacity car pool cars central link Centrality certification commuter rail condo conformity congestion congestion pricing connections consistency coverage crossings CRT cycling DART dedicated dedicated right of way density denver depreciation developers development dynamic pricing economics efficiency Envision Utah equity eugene exclusive extension FAQ favela Federal Funding Flex Bus florida free fare zone freeways Frequent Transit 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 LEED legacy city light rail linear park location LRT lyft M/ART malls mapping maps market urbanism 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 shuttle silver line single family SLC SLC transit master plan slums smartphone snow sprawl standing stop spacing streetcar streetscape streetscaping subdivision subsidy Sugarhouse Sugarhouse Streetcar Tacoma taxi technology tenure termini time-separation TOD townhouse traffic signal tram transit transit networks transit oriented development Transit Planning transponder transportation travel time TRAX trip planning trolley tunnel uber university of utah urban design urban economics urban land UTA UTA 2 Go Trip Planner utah Utah County Utah Transit Authority vmt walking distance web welfare transit Westside Connector WFRC wheelchairs zoning

Wednesday, December 21, 2011

THEORY OF URBANIZATION


ECONOMIC DEVELOPMENT DEMANDS ADDITIONAL SPACE
Urban growth is a reflection of economic growth. Economic activity takes place in space.
As the amount of economic activity taking place increases, so does the amount of space needed to 'house' that activity. The amount of space needed can be provided by making either making more intense use of existing urbanized area, or by making additional urban land available.

BOUNDED CITIES
As a thought experiment, consider a 'bounded city', which can no longer expand in space because of of a 'hard boundary' (Political, legal, geographic, regulatory, etc.). This city is thus limited in its capacity to expand its urban area. But because economic activity takes place in space, contined expansion of economic activity requires additional space. Without the capacity to add additional urban space, existing urban space must be used more intensively. A combination of three factors makes this difficult.

FIXED STRUCTURES
Theoretically, urban land is developed in a manner characteristic with its highest and best use, so that in a context of limited land, urban land would convert to high value uses. In reality, development occurrs in accordance with the highest and best use at the time of development. Changes in the amenity of a parcel over time means that the highest and best use can also change. However, the capacity of the parcel to adapt to these changes is minimal. Once developed, a parcel's land use is fixed by the structure of the developed building. Many structures are so specialized as to be unsuitable for other uses, regardless of changes in the highest and best use. Urban land use thus remains fixed over long periods of time.

PARCEL FRAGMENTATION
Secondly, urban land suffers from fragmentation. Large parcels are partially developed, or broken into smaller parcels. Over time, this process generates progressively smaller and less coherent parcels for development, which are progressively more difficult to develop. The impact of this dynamic is compounded over time. Because of differences in construction and maintenance, different structures depreciate at different rates and are available for redevelopment at different times. This makes it difficult to recombine smaller parcels into larger parcels.

REPLACING EXISTING USES
Redevelopment occurrs when the income generated by new development is sufficient to cover the cost of clearing old structures, erecting new ones, and covering the resultant loss of income from the destruction of old structures. As urban land becomes scarcer, the value of urban land and the resultant rents that can be charged rises, making it more difficult to find a replacement use that will provide sufficient income to be worth redeveloping.

URBAN EXPANSION
Given the constraints posed by re-use, urbanized area tends to expand in response to economic development. But urban expansion does not occurr in a random manner, but in  a pattern dictated by the function of urban land markets. Because the value generated by undeveloped parcels on the urban fringe (greenfields) is extremely minimal, they are developed in preference to redeveloping existing sites.

METROPOLITAN FORM
Employment centers occupy the most central locations—not out of a direct desire for centrality, but because of their primacy in the metropolitan development process. They come first, and the rest of the metropolis orients itself around them. Second most-centrally located are retail uses. While they follow residential in the development process, the competitive advantage represented by a more central location ensures willingness to 'outbid' residential users. Residential uses located at the least central locations, where land values are lowest.

Centrality should be understood in a network sense, rather than in a geographic sense. While their has historically been a correlation between the geographic center and centrality, it is not a causal linkage. Historically, the center of a city occupied the most 'central' location, because it was located en-route to the largest number of destinations. Development of limited access transportation networks such as subways and freeways changes this dynamics, so that proximity to transportation network access points becomes the best measure of centrality.