Abstract
Aggression against passengers can be caused by to less space, not well (or not enough) trained public transport personnel, or by not taking adequate measures. Different groups show different (aggressive) behaviour, such as the malicious behaviour of school children, drunken persons, football supporters and the hard nucleus of criminal young people. The most common measures to prevent this are not always effective. The place of cameras are often well known and offenders do not come into the picture. Directed surveillance is more successfull than the arbitrary extra personnel. If the offender is not directly detected and punished his criminal behaviour can become recidive.