In the most recent assault, a driver suffered minor injuries Thursday when he was hit. A few days ago, two drivers suffered more serious attacks -- one severely beaten and shots fired at a second.
Five trade unions who represent employees at the public transit company GSP Beograd said at least 50 assaults were reported this year. They are calling for panic buttons and surveillance cameras on buses, and for tougher penalties for assaulting drivers.
The unions are planning a protest Jan. 9, which could include a 5- to 10-minute work stoppage.