Twin Cities transit agencies are enacting stricter protocols to keep passengers and operators safe amid COVID-19 concerns, and in some cases are reducing service as ridership has plummeted this week with schools closed and many employees working at home.

Starting Friday, the Minnesota Valley Transit Authority will encourage passengers on the Red Line rapid bus to board and depart buses and pay fares through the back door and prohibit passengers on all buses from sitting in seats directly behind the driver.

The agency serving eight suburbs south of the Minnesota River also is promoting social distancing by asking passengers to spread out on its vehicles and will begin a modified schedule as passenger traffic on express routes fell 60% this week and ridership dropped by 30% on its local suburban routes, said spokesman Richard Crawford.

Metro Transit, which is asking riders to "use transit for essential travel only," may soon follow MVTA's lead, said Ryan Timlin, head of the union representing 2,000 Metro Transit drivers and rail operators. The union and Metro Transit could be looking at having passengers enter by rear doors and possibly suggest that no bus carry more than 10 passengers at a time, Timlin said.

Express routes with too few riders could be cut, and those buses could be deployed to routes with too many riders, Timlin said.

"Those things need to happen; our drivers are vulnerable," Timlin said.

That said, he noted that bus service remains a necessity for many.

"People need to get to hospitals, not just for COVID-19. Nurses take the bus. We are still needed," Timlin said.

Metro Transit already has curtailed service between 11 p.m. and 4:30 a.m. But no other service cuts had been made as of Thursday morning even through the agency estimates that bus ridership has dropped more than 40% this week, compared with comparable weekdays. Light-rail ridership is down more than 50% and Northstar ridership is down more than 80%, said spokesman Howie Padilla.

"We are putting out service to the extent that we can," Padilla said. "We are talking with our partners to see what would be the most responsible thing to do."

Padilla said riders can do their part.

"If they see a bus with 10 people on it, take the next bus, if possible. If a light-rail car has 15 people on it, ask [yourself], 'Can I take the next train?' "

Maple Grove Transit spokesman Mike Opatz said the agency was working on a reduced service plan for express routes because of COVID-19 and is "evaluating potential changes to operating procedures and policies." Starting Friday, the city's dial-a-ride service, My Ride, will no longer group riders on unrelated trips together to minimize passenger loads, Opatz said.

SouthWest Transit, which said ridership declined 90% Monday through Thursday, is making severe cuts to its express routes. Starting Monday, there will be no service at the Carver and Chanhassen transit stations. Trips from the Southwest Station in Eden Prairie, SouthWest Village in Chanhassen and East Creek Station in Chaska will be combined. Buses will run every 15 minutes during peak periods, stopping at all three stations before heading downtown Minneapolis and the University of Minnesota. The same will happen with return trips in the evening.

Additionally, the last bus at night to the southwest suburbs will depart the Oak Street stop at the University of Minnesota at 6:22 p.m. and from 4th Street and Marquette Avenue in downtown Minneapolis at 6:34 p.m. The agency's on-demand ride service, Prime, will not operate on Saturdays.

If ridership slides further, "more cuts will be coming," said CEO Len Simich.

Calls and e-mails to Plymouth Metrolink were not immediately returned.

In Rochester, regular weekday transit service is being suspended and the city's bus service will begin operating reduced service starting Friday. Riders are being asked to keep one seat between them and others at all times and fill the bus from back to front, skipping every other row whenever possible, the agency said.

"Drivers are being instructed to depart stops once their buses are 50% full — or about 20 passengers," the agency said on its website.

Similar moves are being made across the nation. In Madison, Wis., buses are limited to carrying a maximum of 15 passengers. In Pittsburgh, priority seating nearest drivers will be blocked off. In Philadelphia, buses will begin operating on a weekend schedule. In Rockford, Ill., the Mass Transit District is waiving all fares on all services in an effort to reduce surface contact with the fare boxes and increase more social distancing through April 1, according to an announcement on the district's website.