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What Goes Around Comes Around: Would Early 20th Century Street Discipline Be Safer for Connected and Automated Vehicles?

Dr. John N. Ivan
Professor of Civil and Environmental Engineering at the University of Connecticut


At the beginning of the twentieth century the automobile was introduced to the urban street, joining a mix of traffic that included pedestrians, streetcars (aka trollies or trams), and even horse drawn carriages. Being the newcomer to the scene, motor vehicle drivers were forced to accommodate the limited speeds and free movement of the existing traffic modes. This did not last long, as the motor vehicle industry successfully lobbied for order in the street environment to permit the automobile to be able to experience its full speed and mobility potential without interruption by other road users. This radical change in how people experienced urban streets was sold to the public in the name of safety, resulting in the street discipline to which we are accustomed today.

Over a hundred years later we face another potential revolution in traffic on the urban street – the introduction of connected and automated vehicles (CAVs) controlled independently of human intervention. As original equipment manufacturers test CAV technology on urban streets, we are learning that navigating city street environments with mixed traffic (e.g., nonmotorized as well as motorized users) at typical street speeds (25 miles per hour or greater) is proving to be the greatest challenge and has already resulted in pedestrian fatalities. On the other hand, CAV operating experience is showing us that CAVs are performing well in two environments: high-speed limited access highways and low-speed local neighborhood streets.

This should not be a surprise to anyone, since per mile driven, it is on moderate-speed collector and arterial streets that the most road casualties occur in urban areas. This road environment is so challenging for CAVs because it is challenging for human drivers, too. The New Urbanism and Complete Streets movements are revolutionizing the urban street by rethinking the “order” that was imposed a hundred years ago to improve safety for nonmotorized users by reducing motor vehicle speeds in areas with vibrant human activity. Perhaps there is something for us to learn from returning to the street discipline of the pre-automobile age for some areas as we seek to eliminate traffic fatalities in our cities while integrating CAVs into the traffic environment.

Biographical Profile

Dr. Ivan is a Professor in the Department of Civil and Environmental Engineering at the University of Connecticut. He has earned B.S, M.S. and Ph.D. degrees in Civil Engineering at Carnegie Mellon University, Massachusetts Institute of Technology and Northwestern University, respectively. He teaches courses in traffic engineering, transportation planning and road safety analysis and conducts research in the application of statistical forecasting techniques for measuring the sustainability of transportation systems and engineering, especially highway safety and operations. He has been an investigator on 51 funded research projects at a total of over $8.5 million in funding, and published as author or co-author 54 peer-refereed journal articles and 57 peer-reviewed conference papers. He has coordinated preparation for the academic accreditation of the Civil Engineering Program at the University of Connecticut for four visits over twenty years and is an associate editor of Accident Analysis and Prevention. In 2011 he was elected to the Connecticut Academy of Science and Engineering and has been a Program Evaluator for ABET, Inc., since 2012.


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