Comments on: Connecting Residential Density and Fuel Consumption http://la.streetsblog.org/2009/08/11/connecting-residential-density-and-fuel-consumption/ Covering Los Angeles's livable streets movement Tue, 07 Feb 2012 14:06:00 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: BOB2 http://la.streetsblog.org/2009/08/11/connecting-residential-density-and-fuel-consumption/comment-page-1/#comment-20981 BOB2 Tue, 11 Aug 2009 17:22:25 +0000 http://la.streetsblog.org/?p=7051#comment-20981 The research is pretty conclusive on VMT and density. And, most models that are used for transportation planning exagerate the growth in suburban traffic, by the use of linear forecasting that show eternal growth in vehicle miles traveled (VMT) into the future, which implies the need for more freeways. This was the case in Orange County, but in the late 80's and 90's as density rose in the OC, census data and survey data showed that per capita VMT actually fell??? The casality for this is 1) what I have called the Wall Mart-Home Depot effect--as density increases, more retail and jobs are also added, reducing the required travel distances to goods and services. And, 2) the self limiting effects of congestion on the utility of travel, which are underestimated. Our erroneous travel demand models assume, based on linear analysis that as speeds and utility of travel falls, consumption continues to grow (forever). Unless we are somehow making days longer, utility of travel must fall as a function of constrained time. As trip times increase, the cost rises and utility falls, constrained by the time available and allocated for trip making. This fallacy persists despite the fact that it is also against the most basic understanding of economics to assert that as utility falls consumption will continue to grow. How ludicrous is this flawed thinking? SCAG once showed that people would travel in congested conditions from their Palmdale homes to the LA basin jobs-taking 8 hours on the road-working 8 hours-then driving back in traffic for 8 hours. It is, of course, pure nonsense, but was part of the analysis they continued to use (and still use) to recommend additional road capacity. The research is pretty conclusive on VMT and density. And, most models that are used for transportation planning exagerate the growth in suburban traffic, by the use of linear forecasting that show eternal growth in vehicle miles traveled (VMT) into the future, which implies the need for more freeways. This was the case in Orange County, but in the late 80′s and 90′s as density rose in the OC, census data and survey data showed that per capita VMT actually fell???

The casality for this is 1) what I have called the Wall Mart-Home Depot effect–as density increases, more retail and jobs are also added, reducing the required travel distances to goods and services. And, 2) the self limiting effects of congestion on the utility of travel, which are underestimated. Our erroneous travel demand models assume, based on linear analysis that as speeds and utility of travel falls, consumption continues to grow (forever).

Unless we are somehow making days longer, utility of travel must fall as a function of constrained time. As trip times increase, the cost rises and utility falls, constrained by the time available and allocated for trip making. This fallacy persists despite the fact that it is also against the most basic understanding of economics to assert that as utility falls consumption will continue to grow.

How ludicrous is this flawed thinking? SCAG once showed that people would travel in congested conditions from their Palmdale homes to the LA basin jobs-taking 8 hours on the road-working 8 hours-then driving back in traffic for 8 hours. It is, of course, pure nonsense, but was part of the analysis they continued to use (and still use) to recommend additional road capacity.

]]> By: DJB http://la.streetsblog.org/2009/08/11/connecting-residential-density-and-fuel-consumption/comment-page-1/#comment-20921 DJB Tue, 11 Aug 2009 15:55:15 +0000 http://la.streetsblog.org/?p=7051#comment-20921 There's a similar study called "Environmental Characteristics of Smart Growth Neighborhoods - Phase II: Two Nashville Neighborhoods" published by the NRDC in 2003. It compares a denser inner-ring suburb of Nashville with a more diffuse outer-ring suburb of Nashville. The study controlled for household size, auto ownership, and trip making rates (but income data for the specific areas of analysis were unavailable). Both neighborhoods lacked transit service. The result: on a per-capita basis the denser, more centrally-located suburb consumed 1/3 less land (former habitat), 13% less water, produced 7% less vehicular air pollution and 25% less vehicular carbon dioxide. There’s a similar study called “Environmental Characteristics of Smart Growth Neighborhoods – Phase II: Two Nashville Neighborhoods” published by the NRDC in 2003. It compares a denser inner-ring suburb of Nashville with a more diffuse outer-ring suburb of Nashville.

The study controlled for household size, auto ownership, and trip making rates (but income data for the specific areas of analysis were unavailable). Both neighborhoods lacked transit service.

The result: on a per-capita basis the denser, more centrally-located suburb consumed 1/3 less land (former habitat), 13% less water, produced 7% less vehicular air pollution and 25% less vehicular carbon dioxide.

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