"Professionals make mistakes. Doctors made a 100-year mistake called the radical mastectomy, based on an erroneous theory of how cancer spreads. But when studies proved this surgery unnecessary, doctors replaced the once-common procedure with a less damaging treatment in a surprisingly short period of time.
Some traffic engineering techniques are a bit like radical surgery. But unfortunately, traffic engineers as a group have been much slower to recognize their erroneous techniques and replace them with less damaging practices."