SEPTA is adjusting weekday Regional Rail schedules and offering refund options for some riders, the transportation authority announced Monday.

A severe weather service plan will be in effect for two weeks, beginning Tuesday, “to accommodate changing ridership levels.” Credits will be extended for valid unused and partially used passes.

PATCO is also making changes to its weekday service beginning Tuesday “in response to coordinated efforts to slow the spread of COVID-19,” according to the High-Speed Line website.

SEPTA riders with March monthly passes and March 9 and 16 weekly passes on Key cards can contact the SEPTA Key Call Center at 1-855-567-3782. A prorated refund will be added to riders’ Travel Wallets.

Requests involving legacy paper passes must be sent to SEPTA’s headquarters at 1234 Market St., Ninth Floor, Philadelphia., Pa. 19107. More information on the credit offers, including for riders using third party pre-tax benefit providers, can be found on SEPTA’s website.

Other transit services are running normally but could see their own reduced schedules by the end of the week or into the weekend, said Scott Sauer, SEPTA assistant general manager of operations.

“There will be disruptions," he said. "There will be incidents where our employees have difficulty getting to work. There will be places where we cannot run the service that we are advertising.”

A winter storm schedule is a 25% reduction in Regional Rail service and requires 15% fewer crew members to operate, Sauer said. SEPTA will run 581 trains beginning Tuesday, as opposed to the 769 trains it normally has during a weekday.

The reduction in Regional Rail service is due to drops in ridership and staffing, SEPTA general manager Leslie S. Richards said.

“As we respond and do what is needed to slow down, to flatten the curve from COVID-19, we are constantly monitoring the situation, and we will react accordingly," she said.

SEPTA evaluated its Regional Rail schedules after callouts from conductors and engineers prompted cancellations of about a dozen trains early Monday.

About 13 trains were affected, said SEPTA spokesperson Andrew Busch. Cancellations were seen across the system, including the Media/Elwyn, Lansdale/Doylestown, Chestnut Hill East, and Paoli/Thorndale lines, according to SEPTA’s website.

Busch said issues surrounding child care and school closings amid the coronavirus have affected SEPTA’s workforce “like it has with others.” Callouts also impacted a handful of buses Monday.

“As far as I know, we haven’t had any incidence of someone saying they were self-quarantining or anything like that,” he said.

In addition to sweeping social distancing measures in Montgomery County, Gov. Tom Wolf announced over the weekend that Chester and Bucks Counties would be subject to shutdown orders. Philadelphia ordered a shutdown of nonessential businesses Monday.

Mayor Jim Kenney called SEPTA “a major lifeline for people to get to work” at a news conference Monday.

“This is a situation that has no playbook,” he said.

Busch didn’t have Regional Rail ridership figures for Monday morning but said ridership was “cut significantly."

Last week, ridership saw dips on buses, subways and trolleys, and Regional Rail ridership was down 16% Friday compared with weekday averages through last week.

On Friday, SEPTA said it would reinforce best practices to its conductors and workers from Edens Corp., who act as ambassadors and ticket agents on the Regional Rail system, taking tickets and validating Key cards.

Donald Hill, general chairman of the local Brotherhood of Locomotive Engineers and Trainmen, said there were six callouts, two of which were made over the weekend and were child-care related. The remaining four were for unrelated issues.

His concern is making sure the adjustments are well communicated to engineers, and for the safety of the riding public.

“I just hope the service [adjustments] that they will be providing will be enough,” he said.