EDMONTON -- Bus drivers are looking over their shoulders more often following the third attack on a transit operator in just five weeks, says the union head.

"It almost appears it's one after another. When's it going to stop?" said Stu Litwinowich, president of the Amalgamated Transit Union Local 569.

"The operators are probably looking over their shoulders more and more, wondering what kind of activity's taking place on the bus. They're way more cautious."

A 24-year-old man has been charged with assault following the latest incident.

At 11:45 p.m. on Sunday, a man got on an ETS bus at 61 Street and 129 Avenue, cops said.

The driver, in his mid-50s, was allegedly assaulted following a "discussion" over the fare, said police spokeswoman Karen Carlson.

"He got on the bus and then the bus driver asked him for the fare," she said. "Then the bus driver was allegedly assaulted."

The attacker fled on foot, but was arrested by cops a few blocks away after a witness called 911, police said.

The bus driver was taken to hospital with minor injuries as a precautionary measure, said Carlson.

She said she didn't have further details on the alleged attack but said a weapon was not used.

Mitchell Andrew Torangeau, 24, has been charged with assault.

Just last month, a veteran driver was blasted in the face with pepper spray after two teens allegedly got into an argument at the Coliseum transit station on 76 Street and 118 Avenue while trying to board a Route 5 bus.

While that driver didn't suffer serious injuries, the incident mirrored the brutal assault of 58-year-old driver Tom Bregg on Dec. 3.

In that incident, a passenger allegedly dragged him off the bus and kicked him repeatedly in the face and head before fleeing.

Litwinowich said while the union is still keen on optional driver safety shields, it's also interested in research being done by the city on whether to equip operators with panic buttons.

He also applauded a move to install signs on buses in the next few weeks outlining codes of conduct for passengers.

Ron Gabruck, ETS director of safety and security, said ETS continues to test Plexiglas shields, which would essentially enclose the operator.

"Shields aren't going to solve this problem entirely," Gabruck said.

"Most of our operators will probably not choose to use them."

He said despite the three recent incidents, the transit system remains safe.

FRANK.LANDRY@SUNMEDIA.CA