6.1 Association of Transportation Engineers and Technicians of Serbia, Belgrade, Serbia ‑ Member (1959-1995).
6.2 International Association of Public Transport – UITP, Brussels, Belgium ‑ Personal Associate Member (1962-present). Member of the Editorial Board of the Public Transport International journal.
6.3 Institute of Transportation Engineers – ITE, Washington ‑ Life Member (joined in 1965). Member of three technical committees (1968, 1970, 1980); Assistant Chairman, Planning Applications Division (1971‑72).
6.4 Chi Epsilon (1964), Tau Beta Pi (2006).
6.5 Operations Research Society of America – ORSA/INFORMS, Member (1967‑80); Transportation Science Section Council Member (1969‑70).
6.6 Transportation Research Board ‑ TRB, Member since 1967; Representative of the University of Pennsylvania (1968-2010). Chairman of the Rail Transit Committee 1977‑83. One of the initiators of the Light Rail Transit and Commuter Rail Committees; presently member of the Committees on Intermodal Transfer Facilities, Intercity Passenger Rail, and Rail Transit. Emeritus Member of two committees.
6.7 American Society of Civil Engineers – ASCE, Washington ‑ Member (1971-present).
6.8 Transportation Subcommittee, Mayor’s Science and Technology Advisory Committee, Philadelphia, Vice‑Chairman (1972‑80).