He groped a teenage girl while she drove his subway train under the streets of Manhattan, but former motorman Reuben Petrus isn't exactly being ridden out of town on a rail he's not even getting jail time.

Petrus, 43, was sentenced to five years' probation yesterday for the sick incident last year, in which he trapped the 18-year-old in his cramped cab and rubbed up against her while her hands were on the controls of the Q train.

The incident occurred Sept. 2, when the woman sought out Petrus' help because she felt intimidated by six men who were riding in another car in the virtually empty train.

"He convinced her she'd be safer with him" in his cab and then invited her to drive the train," Stolley said.