Wednesday, January 29, 2014

What is Public Transit's Role (if any) in Reducing Traffic Congestion?

Do density and transport resolve congestion? (Cities Matter, Dec. 11, 2013)

Today we review a look at the links between congestion on the one hand and transit, population density and city location. The short answer is that better transit does not correlate with less congestion. The only significant link is between higher urban population density and higher congestion. This is the opposite way to what planners frequently assume- that higher urban densities process more efficient public transit and less congestion. A side result reveals which cities have poorer performance than expected and here there are surprises: in Canada, Vancouver, Ottawa and Montreal have 5-10% higher congestion than Toronto, Calgary or Edmonton. As the contrarian blogger who wrote this article, Phil McDermott , wryly comments: “transit creates a commitment to a land use pattern that promotes congestion, delaying or distorting the decentralisation of employment that might otherwise occur in a well-connected city”.

What was not analysed is the impact of road pricing on congestion and the results from cities which have tried it- from Dubai to Stockholm and from London to Singapore seem to point to this being the best way to reduce congestion and pollution. The conclusion seems to point to a combination of lower population density (i.e. sprawled cities) combined with road pricing as the best option to address congestion in (already sprawled) cities in the US and Canada, rather than expanding expensive and, from this analysis, ineffective
public transit. 

Key Quotes:

“Among the North American cities only population density was statistically significant, explaining 52% of the differences in morning congestion among cities. By and large, as densities increase, so does congestion”

“Boston has higher levels of congestion (48%) than predicted (27%) on the basis of its density (just 800 persons per square km)… The other poor performers based on this analysis include both high density Montreal, Ottawa, and Vancouver, and low density Atlanta”

“The results for European cities were completely different, adding weight to the argument that context matters:.. the poor performers are Warsaw (density 3,100), Marseilles (1,300), Istanbul (9,700), Toulouse (1,100), Rome (3,400) and Brussels (2,600). The better performers include the smaller cities of Malmo (density 3,600), Zagreb (5,700), Valencia (3,000), Seville (5,600) and Bern (2,300).”

“the European evidence also offers no grounds for suggesting that density is a prerequisite either to better commuting conditions or that congestion reflects the quality of transit systems.”
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