Delays were first reported at about 6:30 p.m. Thursday, with Metro-North blaming a disabled train near the New Canaan station.
A train dropped off all of its passengers at the end of the branch, then headed for the yard, when one of the wheels went off the tracks, the spokesman said.
No injuries were reported, and the spokesman called the incident extremely minor. But commuters faced long delays much of the evening. Train service was stopped at Talmadge Hill and buses ran for some trips to and from the New Canaan train station.
The derailment occurred at the Grove Street crossing, which was blocked for nearly four before it was cleared at about 10:30 p.m., Metro-North said.
Buses were running for the rest of the trips Thursday night.
Normal service was expected to resume for the Friday morning rush-hour commute, the spokesman said.
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