The problem that caused cancellations and delays since this morning was traced to electronic equipment that helps control movement, BART spokesman Jim Allison said.
A bus bridge that had been set up between the Concord and Pleasant Hill stations to help passengers at around 8:30 a.m. has since been canceled.
Service was stopped between the Concord and Pleasant Hill stations at about 8:15 a.m. All other lines have been operating on time throughout the day.
