Adopt a 10-Foot Standard for Free-Flow Lanes
SIMPLY PUT, different-width driving lanes correspond to different driving speeds. A typical American urban lane has historically been 10 feet wide, which comfortably supports speeds of 45 mph. A typical American highway lane is 12 feet wide, which comfortably supports speeds of 70 mph. Drivers instinctively understand the connection between lane width and driving speed, and speed up when presented with wider lanes, even in urban locations. For this reason, any urban lane more than 10 feet wide encourages speeds that increase risk to people walking.