Overnight weekend service on the Broad Street and Market-Frankford rail lines will be extended indefinitely, despite the increased cost to the transit agency, SEPTA officials announced Wednesday.

"Late night customers have proven, by riding in record numbers each weekend that this is a service they want," said Joseph Casey, SEPTA's general manager. "That's why even with the increased costs we have decided to continue overnight service."

The overnight weekend trains, which run from midnight to 5 a.m. Saturday and Sunday, began as a pilot program, which was initially set to end Labor Day weekend. SEPTA previously extended the pilot through early November.

The cost to operate the trains, which run every 20 minutes during the 5-hour span each day, is approximately $47,000 per weekend, a SEPTA official told NBC10 in August.

The expense is more than three times the amount SEPTA spent to operate the Nite Owl bus service during the same time periods.

But the staggering cost to SEPTA did not outweigh the demands of passengers. On average, 15,000 riders boarded the overnight trains each weekend since the pilot's launch on June 15, according to the transit agency.

The Nite Owl buses, however, averaged about 9,000 passengers, SEPTA officials said.

The transit agency will continue to evaluate the program to determine areas where it can reduce costs without compromising safety.

Contact Alison Burdo at 610.668.5635, alison.burdo@nbcuni.com or follow @NewsBurd on Twitter.