From Expressways to Boulevards
What can be done with expressways that cut through communities? In the Paris region as in many large cities, the most common solution is to hide them behind noise protection walls or bury them under a slab. But you cannot do that everywhere of course.
Other solutions exist and many local authorities are now considering converting expressways into urban boulevards. But the development costs, the technical complexity of the project along with the institutional framework, and the fear of increasing traffic congestion make think twice the decision-makers.
Successful converted highways abroad
Removing expressways from inner cities has positive impacts on neighborhood regeneration and city-wide renaissance, without impeding metropolitan mobility. Converting them into boulevards reveals mix-use development potentials and can open up waterfronts for leisure or other uses. Part of the traffic induced by the former expressway tends to disappear, while some commuters shift to public transport, cycling, walking or car sharing.
Local accessibility for all improves while regional traffic remains possible at lower speed. Improved street connectivity and a walkable environment increase pedestrian activity. Less vehicle trips and speeds tends to reduce air pollution, noise and summer temperatures, helping cities to face climate and health challenges.
Some drawbacks can be observed: more pedestrians and cyclists using heavy traffic roads can result in more accidents: Boulevards need to be carefully designed as multi-use public spaces and monitored after opening. Financing projects can be challenging, but costs involved are often lower than long-term upgrade or maintenance of aging infrastructures.
Urban expressway conversion does appear as an instrument in implementing long-term livable and carbon-free city strategies and may be a paradigm shift in urban and transport planning. Successful projects require high-level political leadership and public participation. They are usually supported by public opinion.
Six case studies
In the United States, Canada, Asia, Europe, cities suddenly cut through by expressways chose to remove and transform them into multi-use boulevards. How did they get through to it? Under what conditions? With what impacts on mobility, urban planning, the environment and public finances? What lessons can be learnt from these experiences?
With some 500 km of metropolitan expressways, the Paris region needs to rethink the future of its network, in the context of policies aiming at urban intensification and reduction of car-use. To provide feed for thought to decision-makers of the Grand Paris, IAU île-de-France published six case studies (in French): New York (Sheridan Expressway), Portland (Harbor Drive), New York (West Side Highway), San Francisco (Embarcadero Freeway), Seoul (Cheonggyecheon Expressway) and Vancouver (Viaducs Dunsmuir & Georgia).