In the eight years since the road diet for Madison was first proposed, research on road diets has evolved considerably. What was once a “slam dunk” case should now be re-considered.
Road diets don’t make roads safer, just less used. Initial research found that accidents dropped on roads put on road diet. This is true, but it is also true that drivers end up seeking to avoid the constricted roadway. When the decline in use is factored in, a large-scale study of road diets found no decrease in accidents/mile, meaning there is no real improvement in safety (Huang et al., 2002, Transportation Research Record). Meanwhile, traffic diverted to side streets may cause new safety problems, with one recent study finding “speeders outside the road diet area rose, with the percentage increases being fairly large, in the double digits” (Nixon et al., 2017, Mineta Transportation Institute).
Road diets increase biking and they do make streets more pleasant for pedestrians and bikers. But the benefits often aren’t that substantial. For example, one highly-touted project in San Francisco found a 54 percent increase in bike traffic after initiating a road diet. That sounds great, but the reality was that bikers during the a.m. rush hour increased from a mere 37/day to 52/day (Polk Street Road Diet Project, 2001 Report from the San Francisco Department of Parking and Traffic). That’s not a strong benefit. Moreover, Oak Park already has good biking options just north (Washington) and south (Jackson) of Madison. Do we really need to enhance biking on Madison, perhaps by diverting car traffic onto these good bike routes?
Madison may be a bad fit for a road diet. Road diets may have weak benefits, but they’re often advertised as doing no harm. This is because even though they reduce traffic lanes, they provide a turn lane, helping to reduce turn-related congestion. The problem is that Madison already has turn lanes at all major intersections; there’s not much of an issue with turn-related congestion.
It’s unclear, then, how the road diet idea applies to Madison. In fact, according to the village’s presentation, Madison may have too much traffic for a road diet. The presentation notes that when a road diet is applied to streets carrying more than 875 vehicles per hour per direction the diet “may induce operational changes and concerns.” By the village’s estimate, however, Madison was already slightly exceeding that level of traffic during rush hour in 2014 (https://www.oak-park.us/sites/default/files/planning-documents/madison/2016-06-13-madison-street-presentation.pdf). If traffic on Madison has increased since 2014, the road diet plan may no longer be reasonable.
As the research on road diets has evolved, so should the village’s plan. Streetscaping and resurfacing would be great, but a road diet may increase congestion without any major safety benefits.
Bob Calin-Jageman is an Oak Park resident.