Disappearing Traffic

Reduced demand (the inverse effect)

Just as increasing road capacity reduces the cost of travel and thus increases demand, the reverse is also observed – decreasing road capacity increases the cost of travel, so demand is reduced. This observation, for which there is much empirical evidence, has been called disappearing traffic, also traffic evaporation or traffic suppression, or, more generally, dissuaded demand. So the closure of a road or reduction in its capacity (e.g. reducing the number of available lanes) will result in the adjustment of traveler behavior to compensate – for example, people might stop making particular trips to patronize local businesses, condense multiple trips into one, re-time their trips to a less congested time, use online shopping with free shipping, or switch to public transport, carpooling, walking, bicycling or smaller motor vehicles less affected by road diets, such as motorcycles, depending upon the values of those trips or of the schedule delay they experience.