Wednesday, July 3, 2013

The Benefits of Landscaped Medians

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Medians--especially medians with trees--enhance the pedestrian environment by providing beauty, shade, and a refuge for people crossing busy streets. Yet car-oriented roadway design standards can sometimes conflict with pedestrian-friendly design goals, sacrificing pedestrian amenities in the name of "safety." This was the case in Washington state, where cities that wanted to create landscaped medians featuring trees were thwarted by Department of Transportation standards that forbid any fixed objects (like trees) in a roadway's "clear zone."

In order to allow a deviation from DOT standards in certain contexts, a series of studies were conducted to evaluate the impact of adding small trees to a road's median. The results, the entirety of which you can read in this report, show the adding small trees to a median doesn't significantly increase crash rates, crash severity, or injury crash rates.

From the study:
It appears that adding small trees to landscaped medians does not have a detrimental effect on safety. Installation of medians and access control as part of a more general increase in access control generally result in a decrease in midblock crashes, but an increase in crashes occurring at intersections where turning movements are allowed, in large part because turns are concentrated at those locations. These increases are a fraction of the midblock gains, resulting in improved safety overall. 
In other words, adding small trees to a median doesn't have an effect on roadway safety, but the median itself increases overall safety on the roadway--good news for both pedestrians and drivers. 

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