Dr Mitchell worked at the British Transport Research Laboratory from 1970 until he retired in 1994. He became Head of Access and Mobility Division in 1975, responsible for research on the effects of transport policies on different groups of people, including elderly and disabled people. From 1982 he ran the Environment Divison. From the early 1980s he also ran TRRL’s research on transport for disabled people, led the team that produced the British specification for easy access local buses and was joint Chairman for the IHT Guidelines “Reducing Mobility Handicaps”.
After retiring from TRL, he worked for Transport Canada for nine months as a Visiting Expert on the implications of Intelligent Transport Systems for older and disabled travellers. He contributed as an observer to the OECD report “Ageing and Transport – mobility needs and safety issues”, and was a member of the TRB task force that updated the report on transportation for an ageing society. He was co-chair of the TRB Committee on Accessible Transportation and Mobility 2004-10, and a member of the TRB Committee on the Safe Mobility of Older Persons.