Police are stepping up patrols in a bid to stop gangs of youths throwing stones at Nottingham's trams.
Officers say youngsters in the Bulwell area have broken windows and caused annoyance to many residents of Neston Drive.
They say the teenagers may hurt or even kill someone.
Pc Derek Pickering said: "If a stone gets thrown through a window, if it's the driver's window the consequences don't bear thinking about."
He added: "They're putting wood and big branches on the line and cramming them into the points."
The operation to catch the youths responsible is part of the Respect for Transport campaign which aims to get more people to use public transport by reducing crime and disorder on trams and buses.