Urban studies pioneer Jane Jacobs stressed the importance of short blocks in building a sense of community. New Urban News reports that neighborhoods with more intersections (and fewer cul de sacs) are also safer, in part because motorists have to repeatedly slow down. Philip Langdon summarizes a new study by transportation researchers Wesley Marshall and Norman Garrick:
New urbanists often identify “connectivity” as a critical factor in street design. Marshall and Garrick suggest that the focus should be defined a bit differently. They say that what matters most, from the perspective of reducing deaths in traffic accidents, is how many intersections there are in a given land area. The more dangerous cities had 41 percent fewer intersections per square mile. (In the lingo of Marshall and Garrick, this measure is “real intersection density.”)
A street network with low intersection density might have fewer than 81 intersections per square mile. A street network with high density — which is much safer — might have more than 225 intersections per square mile. With a high number of intersections per square mile, fatalities decline and the frequency of severe injuries decreases, too. Communities with many small blocks — a description that fits many older cities and new urbanist developments — tend to have more intersections.
Suggestion: Go to your next neighborhood meeting with a list of blocks that could be cut in half. And fight pedestrian bridges that allow cars to accelerate to highway speeds (like this thankfully abandoned project).