All Member Forum

I'm just as afraid of congestion as the next person, but senselessly adding lanes only serves to help the symptoms, not the underlining disease. In many ways reducing congestion makes it easier to drive, which leads to more cars on the road. In the face of congestion, we have to be brave and realize that sometimes a short term increase in congestion (caused my bus-lanes or road diets) could lead to long term gains in public and environmental health.

It is important that transportation professionals approach this and other similar estimates of congestion costs with healthy skepticism. They have been criticized for using biased analysis practices:
* They use freeflow baseline speeds (since traffic speeds often exceed legal limits, a major portion of the estimated congestion "cost" is simply speed limit compliance).
* They use higher values of travel time than average motorists are actually willing to pay for marginal travel time savings.
* They use upper-bound estimates of future traffic growth - in fact, traffic volumes and congestion costs peaked in 2006 and have declined somewhat since due to demographic and economic trends (aging population, rising fuel prices, improved travel options and changing consumer preferences).
* They fail to account for the increased fuel consumption, pollution emissions and accidents that result if traffic speeds increase from moderate congestion to freeflow.
* Some of their statements are illogical hyperbole. For example, the INRIX report compare 17 years of total projected congestion costs with one-year's total tax expenditures - these are unrelated. It would be better to compare congestion with other transportation costs such as vehicle, roadway, accidents and pollution costs; measured this way, congestion costs are modest. For example, would be more accurate but anti-climatic to say, that congestion adds 3-5% to the total travel time and fuel costs.
This is not to suggest that transportation professionals should ignore congestion costs, but it is no longer appropriate to assume that it should be treated as the primary cost and congestion reduction is necessarily the primary urban planning goal. We need more realistic information on congestion costs and more comprehensive information on the full costs and benefits of potential congestion reduction strategies in order to identify "win-win" solutions; the congestion reduction strategies that help achieve other planning objectives.
For more discussion see:
Boo! The annual Carmaggedon scare is upon us (http://cityobservatory.org/carmaggedon )
"How Not To Measure Traffic Congestion—Hold the Hyperbole, Please!" (http://www.planetizen.com/node/71689)
"Why Commute Times Don't Change Much Even as a City Grows, Two words: Balanced Transportation" (http://tinyurl.com/k7thhae )
"Congestion Costing Critique: Critical Evaluation of the “Urban Mobility Report” (http://www.vtpi.org/UMR_critique.pdf )