The late William D. “Bill” Kennedy was instrumental in the development of tunnel ventilation systems for road and rail tunnels worldwide during his 46-year career with Parsons Brinckerhoff. He was among a group of engineers that developed the Subway Environmental Design Handbook under contract to the US Department of Transportation in the early 1970s and, as part of that project, he led the development of the Subway Environmental System (SES) software program, widely considered the standard tool for the analysis and design of transit systems.