Does a Grande Latte Really Stir up Gridlock?

Abstract

Does a stop that a commuter makes on the way to or from work adversely affect peak period traffic? This question is addressed by examining the effects of stops made as part of commute journeys on daily, as well as peak period, travel time and distance, in a 6-week travel diary data set from Germany. Increments in travel time and distance due to stops made in commute journeys are evaluated, and a panel regression analysis is performed to determine contributions of stops of different types to travel time and distance. It was found that the travel time and distance of a commute journey increase with the number of stops and that incorporating stops as part of commute journeys tends to make daily travel more efficient, with more distances traversed in relatively less time than when the same number of stops are all made outside the commute journey. Nonetheless, stops in commute journeys do add to peak period travel time and distance. Stops made before work do not produce much incremental travel in the morning peak period. Stops made after work, however, substantially add to peak period travel time and distance as well as daily travel time and distance. In particular, a home-based journey made after returning home contributes to afternoon peak traffic more than does a stop in a work-to-home commute journey.