Muni spokesman Judson True said regular service of the J-Church and N-Judah lines resumed around 3:50 p.m.
The crash happened around 10 a.m. when a "rescue train," which was in the process of moving an out-of-service disabled train, jumped the tracks and struck the railing of an accessibility ramp used by passengers with disabilities, according to True.
There were no injuries, True said. An operator and a maintenance worker were on the disabled train and there was one operator on the rescue train.
Many passersby stopped to photograph the accident and take a look at the damage near the front end of the train. A door, which smashed against the railing, was eventually removed from the train and a blue tarp was set up in its place.
Preliminary information had indicated the rear part of the train impacted the railing.
Crews used a hydraulic jack to lift the 78,000-pound trains and crews slowly moved them on a slide plate, a flat piece of aluminum, True said.
The operators of both trains will be placed on non-driving status and will be subject to drug and alcohol tests as part of standard procedure, True said.