Thursday, November 15, 2007

CNU: 2007 London Transport Summit (Day 2--Afternoon)

During the afternoon of the second day we listened to several excellent presentations.

Lucinda Gibson (VP, Smart Mobility) gave a fascinating and insightful look into the world of traffic modelling. This realm is often looked on with some scepticism by new urbanists and smart growth advocates because model results rarely back up there experience of mixed use and compact development advantages. Lucinda described the reasons for model failure; these can be placed in two categories, both of which are common place. Firstly the purposeful distortion of models where they are deliberately skewed to meet political agendas, this can be readily done by giving model variables unrealistic values in a subtle but systematic way. Secondly, the real errors of models that do not capture the traffic system accurately. In terms of demand there are a whole range of factors which would likely reduce the outcome, from increasing oil prices, climate change legislation and increasing environmental awareness, whilst these cannot reasonably be included in a model they should be factored in to analysis of the model and appreciated as downward factors that increase the likelihood of lower ranges of traffic. This talk was fascinating to me and i`m sure that anyone working against highway extension would do well to heed Lucinda's advice and look carefully at the traffic model both in terms of its values and how they where derived and any significant exclusions.

Yodan Rofe (Professor, Ben-Gurion University of the Negev) then gave a talk on the use of urban Boulevards as an alternative to urban motorways (highways). Yodan made a powerful case for the use of pedestrian realm as the new urban paradigm. In the case of an urban Boulevard street life is encouraged by having wide pavements and then some parking and a slow moving access street, after this is a broad tree planted area bordering the central through traffic lanes which contain high speed vehicles. Studies have found that this combination of barriers between pedestrians and the fast moving traffic is sufficient to make development along boulevards possible. This is in stark contrast to current motorways (highways) running through cities which are often at different levels and protected by barriers and fencing. Motorways currently offer no accommodation between place and transport function, they are human repelling and street life destroying. The quantity of recoverable urban highways is vast.


Jacky Grimshaw (VP, CNT), Norman Garrick (Associate Prof. UCONN)and Hank Dittmar (CE, Prince's Foundation) then spoke about the reasoning behind LEED-ND. The case was made, and quite convincingly, that buildings rated in isolation of there context risk failing the sustainability challenge. For example a company moving out of a high density mixed use urban setting into a low density single use suburban setting is almost certainly going to force part of its workforce off mass transit and into there cars. Journeys and emissions will increase, and the true advantage of a LEED-Platinum building may be in doubt; greater emissions in the transport/building total are likely even if the old building was relatively inefficient. There where a variety of data used in these presentations but with some overlap, Kenworthy's data which is well known was used, but other data which addressed some critiques of the aforementioned data set where also presented. Among the more striking correlations found was presented by Norman Garrick who showed a phenomenally tight match between year of incorporation of US cities and road fatalaties!

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