Bicycles, shopping trolleys and rocks thrown on the track are causing havoc on the new rail extension to South Morang.
Sergeant Peter Fraser, of the Epping Police transit unit, said the senseless crimes could cause death or serious injury.
He said he was “disgusted” at the incidents, which started on the Epping train line, especially between Epping and South Morang stations, several weeks ago.
He said commuters also faced danger from people throwing rocks at passing buses, especially in McDonalds Road, Epping.
“We have seen accidents result from this type of activity in the past,” Sergeant Fraser said.
“This type of behaviour is not only unacceptable but can result in serious injury or even death in the worst instance and it won’t be tolerated.”
Police were now targeting these offences and would take a ”no tolerance” approach, Sgt Fraser said.
“Anyone caught behaving in such a negligent manner can expect to be prosecuted to the full extent of the law.”
