What is the real cost of traffic?

The American Automobile Association (AAA) has issued a report on the cost of traffic. The results run counter to what most people would expect. The two graphs below were prepared by Pedestrian Inroads from the AAA report. They show graphically a point the report states plainly: congestion is a significant cost, but almost everywhere, crashes are a far greater cost.

 

 

 

 

 

 

 

The study compares the economic costs of crashes vs. the costs of congestion. Costs include delays, lost work, and medical costs, among others. See the report here (1MB PDF) for a complete discussion of the methodology.

Reading the report leads the reader to the following important conclusions:

• The cost of traffic is dominated by crash costs. Except for a very few places that manage snarled but not terribly deadly traffic, lowering crash costs is a much more promising strategy than striving for lower congestion costs. This is perhaps most striking in Seattle. Congestion dominates the traffic discussion in Seattle, even though congestion is not particularly bad. Conversely, Seattle's streets are among the most dangerous, pushing overall traffic costs near the top in the US. If Seattle had crash costs as low as San Francisco, the city's overall traffic costs would be the lowest of any major US city.
• The smaller the place you live, the more traffic generally costs you. Not because of congestion of course, but because of crashes. Partly because of greater travel distances, the further you get from the city, the more crashes there are. (When looking at major cities, the study includes nearby suburbs. )
• It's impossible to build enough roads for everybody to go at full-speed wherever they want whenever they want, but even if we could, it wouldn't have that much effect on the cost of traffic, because as vehicle miles rise, so do accidents and the costs associated with them.
• These are just economic costs, not the human costs. The human cost of waiting in traffic isn't much. The human cost of being in a car crash is often extreme. Nor are the environmental costs considered.
• Some places are doing much better than others. According to AAA, Miami and Phoenix are significantly worse than the rest of the country for traffic, and the difference is in crashes, not congestion. Conversely, San Francisco and Eugene are doing much better than everyone else. It's interesting that the places with low traffic costs are also places that are known as pedestrian- and bike-friendly places. This suggests that effective pedestrian and bike safety facilities are actually profitable: they can save more money in crashes than they cost to install and maintain.

However, as noted in  this article from Eugene quoting Pedestrian Inroads founder Andrea Okomski, even in a place like Eugene with low crash costs, the costs of car crashes are still far too high.