The problem started just before 5 a.m. on the tracks between the Daly City and Colma stations, BART spokesman Jim Allison said.
As of 1 p.m., trains from Pittsburg/Bay Point to San Francisco International Airport were traveling on time after being delayed by up to 20 minutes, Allison said.
Trains from Dublin/Pleasanton to Millbrae, which were being turned around at the Daly City station, are running their full course, according to Allison.
