A & B Rail Services says on the company's website that they were notified late Friday by Alberta Occupational Health and Safety that they could resume operations.
The company says employees are now back on the job.
The trio was hit by a CN freight train last Wednesday morning as they cleared snow and ice from rail switches along some tracks in the city's northeast.
Police have said they were using snowblowers and wearing ear protection and couldn't hear the approaching train.
The train sounded its horn and hit the brakes as it slid toward the workers on the icy tracks.
Two of the men have now been released from hospital while the third was still being kept for observation, though the company said he was in good condition.
"A & B Rail Services Ltd. continues to work with, and fully cooperate with, all government agencies and CN on their investigations, while continuing our own," the company said.
"Until all investigations are complete we will not be releasing any related information."