Since Friday is a weekday as well as the last shopping day before Christmas, some might think SEPTA should beef up service, not cut back.

The agency's basic plan, however, calls for a Sunday schedule for regional rails, and a Saturday schedule for the Market-Frankford Line, the Broad Street Line, trolleys and most bus routes.

That's a significant reduction in service, but riders needn't worry, said spokesman Richard Maloney.

The transit agency not only checked with employers and the Chamber of Commerce, but took a close look at other years when Christmas Eve fell on a Friday.

"We found that while you do have an increased number of shoppers, there's a significant dropoff in the number of people going to work," he said.

Although city agencies will be open, federal offices, almost all courts, public schools, and many non-retail businesses will be closed.

Many workers opt for the day off, and some businesses close early.

"We're very confident that we've scheduled correctly," Maloney said. "We're expecting in the aggregate many fewer people than a normal Friday."

Normal Friday ridership is about 1 million people, he said.

Christmas Day, Saturday, Dec. 25: Most services will be on a Sunday schedule, but some will be on a reduced Sunday schedule. Regional rail will have "a special holiday schedule." The day with the fewest riders every year, Maloney said.

New Year's Eve, Friday, Dec. 31: All services will be on a Saturday schedule, with increased late-night service on regional rail.

New Year's Day, Saturday, Jan. 1: All services on a Sunday schedule.

For details, go to www.septa.org/events/holiday.html or call SEPTA customer service at 215-580-7800.