Celebrating the Legacy of Dolf May, a Trailblazer in Traffic Flow Theory

“At one time or another most of us have been a student of Dolf May,” wrote ITE in a tribute to the transportation giant who passed away on August 23, 2023. Adolf (Dolf) May’s research and contributions to the design, operation, and simulation of freeways, rural highways, urban streets and intersections have left a lasting impact on our profession.

While Dolf’s career included working for a consulting firm and for the Illinois Department of Transportation (where he was the first person to implement a freeway ramp meter), he is best known for his work as an educator and researcher. Dolf worked for nearly 40 years at the University of California, Berkeley, published more than 300 technical papers, and supervised the research of more than 25 doctoral students. In 1990, he authored Traffic Flow Fundamentals, a book that is still widely used to explain the principles of traffic flow theory and application.

Many members of the Kittelson team have benefited from Dolf’s mentorship and knowledge. Dolf was an advisor to Kittelson founder Wayne Kittelson at UC Berkeley, ultimately guiding him to consulting engineering as a career path and to his first job in the field.

“Dolf introduced me to his fellow peers at connections at every TRB Annual meeting, appointed me to the role of Secretary of the Highway Capacity Committee, and was an unsurpassed model for organization and leadership through facilitation,” said Wayne. “He was a unique and amazing person and a wonderful teacher.”

“Dolf gave a guest lecture on Highway Capacity Manual freeway analysis in my undergraduate transportation engineering class at UC Berkeley,” said Principal Engineer Lee Rodegerdts. “I did not realize at the time just how big of a deal Dolf was.”

Senior Principal Engineer Nagui Rouphail met Dolf through the Highway Capacity Committee in the 1980s. “Dolf gave me my first leadership role in that committee as Chair of the Transit Capacity Task Force-so while his giant contributions to the profession have been primarily on the Highway side, he also cared about transit and its integral place in the committee’s activities,” said Nagui. Nagui also worked with Dolf on the Freeway Facilities project that gave birth to the FREEVAL model’s first incarnation in the late 1990s.

In 1990, Dolf was elected to the National Academy of Engineering in recognition of his contributions to traffic engineering and traffic flow. His other recognitions included the Theodore M. Matson Award (1992), the Transportation Research Board’s Distinguished Lectureship (1994), and a Caltrans award for Excellence in Research (1987).

Even in retirement, Dolf worked to better the people around him, helping to create the Amazing Grays and the Sunshine Cart to provide visits, support and wheelchair walks for residents in skilled nursing. He passed away in Santa Barbara, California at the age of 96.

“Dolf’s legacy still affects the profession today, and so does his educational contributions through his seminal Traffic Flow Fundamentals textbook and his many papers and presentations,” said Nagui. Through his fundamental contributions to highway operations and other aspects of transportation engineering, Dolf will continue to have many students in the years to come.

Photo credit: Legacy.com