SEPTA officials apologized Thursday for keeping Regional Rail passengers in the dark about rush-hour delays Wednesday evening that affected 68 trains.

"Beyond the mechanical problem, we were also delayed in getting concrete information out to customers, and that only heightened frustrations," SEPTA said in a statement issued to riders Thursday.

An empty Paoli/Thorndale train on its way from a rail yard to Center City broke down at 4:50 p.m. at a junction near 16th Street and Indiana Avenue in North Philadelphia, partially blocking a key intersection and making it difficult to operate switches, SEPTA said. Trains on other lines were quickly affected.

Trains were delayed from six to 52 minutes, with most 15 to 30 minutes late. About 20,000 passengers were affected.

The SEPTA statement said that "in the age of social media, there are many who believe we should be able to instantaneously communicate detailed information explaining exactly what is going on and what impact it might have on that moment's commute.

"It all comes down to a question of balance - quickly delivered bad or incomplete information or good information that has the benefit of a few minutes of investigation - which is more valuable to customers in the long run?"

"Was 30 minutes too long a time before we had a full-scale communications effort for last night's incident? Absolutely yes, and we will take our licks on that one," SEPTA said Thursday. "We continue to look at ways to improve our processes including the idea of establishing defined windows of time, based on the situation, when customers can expect to begin getting service delay information."

On Thursday, a smaller number of trains were delayed by switching problems, mainly caused by the day's high temperatures that caused rails to expand, SEPTA spokeswoman Jerria Williams said.