AS THE STATE’S ECONOMY begins to reopen, the MBTA intends to manage COVID-19 ridership risks with policies that strongly encourage but don’t mandate social distancing and the wearing of face coverings.

At a meeting of the T’s Fiscal and Management Control Board on Thursday, the state’s top transportation officials said they plan to continue offering reduced Saturday levels of service for the next several weeks and then slowly ramp up service as the reopening progresses.

Transportation Secretary Stephanie Pollack said she believes the T can balance supply and demand for transit services – and allow riders to socially distance – if everyone does their part. She said demand for transit services will remain low if residents continue to stay at home, businesses slowly reopen, colleges and museums remain closed, and large businesses keep their employees working from home. Pollack said businesses employing 150,000 workers have pledged to do that.

“The T adding service right now would actually send a signal to people that it’s time to head to Boston,” Pollack said, noting that Boston Mayor Marty Walsh is trying to discourage that.

The T’s current plan calls for continuing Saturday levels of service through mid-June when phase two of the governor’s four-phase reopening plan is scheduled to start. During phase two, some extra buses may be added to high demand routes, subway service will expand slightly, limited ferry service will return, and Blue Line service will return to normal, pre-COVID levels.

On the supply side, MBTA General Manager Steve Poftak said the transit authority is constrained by its workforce. He said the agency has 2,683 employees who operate vehicles and a portion of them are dealing with COVID-19 themselves. He said on a typical day last week a quarter of the agency’s bus drivers were not available due to COVID-19 leaves.

A passenger on a Silver Line bus running from Chelsea through East Boston to South Station earlier this week took a picture showing masked riders bunched fairly close together. Poftak said the T has been adding additional buses to the Silver Line, but wasn’t able to do that on the day the picture was taken.

Joseph Aiello, the chair of the control board, said the T has pledged to add more service to subway lines and routes if traffic picks up sooner than expected.

Monica Tibbits-Nutt, the vice chair of the board, said she believes crowding is likely to be a recurring issue on buses due to the shortage of vehicles and operators. She noted bus ridership has rebounded to 24 percent of normal levels, a much higher percentage than any other mode of travel.

“That’s going to continue to increase and potentially at a rate that we are not foreseeing,” she said, noting that the increase in ridership is likely to create problems for riders trying to physically distance from one another.

Brian Lang, a member of the control board, said the T needs to set standards for how many riders a bus or subway car can accommodate safely during the COVID-19 pandemic. “What does social distancing mean on a bus, on a subway platform, on a subway?” he asked.

Poftak said the T’s service levels will be informed by new crowding standards the agency has developed. He said the T is adopting the World Health Organization standard of 3 feet for physical distancing as opposed to the US Centers for Disease Control standard of 6 feet, which is the one typically cited by the Baker administration and most other US transit agencies. Using the WHO standard, Poftak said, a 40-foot bus that used to be considered crowded with 56 passengers will now be considered crowded with 20.

The T’s standard for crowding on other vehicles is 31 passengers on a 60-foot bus, 46 passengers on a Green Line trolley, 66 passengers on a Red Line car, 62 on an Orange Line vehicle, and 42 on a Blue Line car.

Those numbers differ slightly from those the business group A Better City calculated in a recent report. The ABC report used both WHO and CDC standards, and calculated 22 and 10 passengers, respectively, for a 40-foot bus; 18 and 45 passengers for a Green Line trolley; and 21 and 57 passengers for a Red Line car.

Poftak emphasized that the MBTA’s calculations are intended to inform the level of service needed to avoid overcrowding.  “We view this as a crowding standard as opposed to a capacity limit,” he said, adding that signage would promote social distancing but marking which seats could be used on buses and subways would not be done because it might interfere with cleaning efforts.

Poftak has indicated in the past that drivers and other T staff would not be expected to enforce any passenger limits. No members of the control board questioned that approach Thursday, nor did they question his use of the WHO standard.

Rick Dimino, the president of A Better City, issued a statement welcoming the T’s embrace of “capacity standards.” Dimino said he assumed the MBTA adopted the WHO standard in consultation with Massachusetts public health officials. “Capacity targets need to go hand-in-hand with a well-developed implementation plan that should include a series of actions to support physical distancing, such as deploying seat markers and signage and a dynamic monitoring, assisted compliance, and enhanced customer services initiative,” Dimino said.

On subway platforms, Poftak said, T officials are just starting to think about crowding standards. He said the T is considering making paths in and out of the subway system one-way to reduce passenger interactions.

Poftak also restated the T’s policy on face coverings, which is facing resistance from the Boston Carmen’s Union. While Gov. Charlie Baker has said face coverings are required on the T, Poftak has pointed out that the governor’s policy does not require people with certain medical conditions to wear them and T officials are also barred from asking for proof of medical conditions.

“While we expect customers to comply, the MBTA will not refuse service to people who are not wearing face coverings,” Poftak’s presentation to the board said.