Trees planted along roadways have many benefits for both pedestrians and automobiles. Beyond providing shade for sidewalks and lowering the temperature on hot summer days these trees have a calming effect for traffic. Studies show that cars drive slower when street trees are planted in rows along the street. Perceived drive time is shortened when streets are lined with trees. Another benefit of tree lined streets is drivers' heart rates are reduced when commuting.
Trees alert drivers to the fact they are in a neighborhood and that there may be pedestrians present. Great Streets, by the internationally known urban planner Alan B. Jacobs notes that wide streets feel primarily like a transportation corridor, not a place where people live. Jacobs also cites research showing that for many people trees are the most important single characteristic of a "good street"