But the engineers' union, The Brotherhood of Locomotive Engineers and Trainmen, calls the cameras an invasion of privacy. It is calling for a cell phone jamming device instead.
Metrolink activated the cameras earlier this month.
"Metrolink is disappointed that the Brotherhood of Locomotive Engineers and Trainmen has taken this action instead of supporting our efforts to advance the safety of passenger train service," the rail authority said in a statement released to Eyewitness News Tuesday. "This program is a vital piece of Metrolink's safety program and was undertaken with the goal of enhancing the safety of our passengers and Metrolink and contractors employees."