It happened at around 7:45 p.m. on Thursday at the 42 Street-Grand Central Station.
The 55-year-old worker was looking out of the conductors' window while onboard a stopped northbound "5" train when a man suddenly punched him in the face.
The attacker then ran off.
EMS rushed the victim to NewYork-Presbyterian/Weill Cornell Medical Center in stable condition.
The attacker is described as man with a medium complexion, approximately 35 to 39 years old, 6'2" inches tall, a medium build, and short black hair. He was last seen wearing a black jacket, gray hooded sweatshirt, and blue jeans.
Anyone with information in regard to this incident is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or, for Spanish, 1-888-57-PISTA (74782).
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