The loss of road capacity and self-compliance: Lessons from the Cheonggyecheon stream restoration

To restore the Cheonggyecheon stream in downtown Seoul, the urban expressway built over the stream was demolished and the number of lanes was decreased from four to two lanes in both directions. Because Cheonggyecheon street is an important link and major arterial connector of Central Seoul and the Eastern part of Seoul, many people thought that changes made to this major road would result in congestion problems. We performed this study to analyze the impacts of the reduction in vehicular capacity of a major street in a large city on commuters' travel patterns and behavior. We monitored traffic volume and travel speed to determine the impacts of the reductions using travel behavior surveys and by analyzing modal shift changes. We performed both short-term monitoring after the restoration work and then continued monitoring over a period of several years to determine the long-term impacts of the restoration project. Whereas travel speed declined and traffic volume increased immediately after the construction work, the number of subway passengers increased and the number of road trips decreased simultaneously. This implies that travelers change their behavior patterns and are self-compliant, even in response to major travel disturbances.