Dozens of RTD bus and rail rides were canceled on Friday after an unusually high number of drivers notified supervisors they were unable to work due to the inclement weather and bad roads led to shutdowns of several bus routes.

Light rail trips on the D, E, H, R, and W lines are likely to be canceled through midnight, Regional Transportation District officials announced. Difficult road conditions due to the snowstorm that slammed metro Denver Wednesday night and Thursday have forced the suspension of service on bus routes, including the CV and EV routes and the NB route between the Nederland Park-n-Ride stop and Eldora.

Trips were canceled on almost all the light rail lines, though not the A line that runs from Denver’s Union Station to Denver International Airport, RTD special projects manager Pauline Haberman said.

Along the W light rail line that runs west from central Denver to Golden, at least 35 trips had been canceled before 2:30 p.m. And trips were canceled along more than 40 bus routes.

Bus drivers and train operators “are calling in related to the weather. It was a big increase in operators calling in unable to come to work,” Haberman said. “It’s unusual to have this number.”

The absences threw off schedules, creating uncertainty for riders. “It puts us onto a different frequency of travel. If a trip is dropped, if you are expecting a train or bus every 15 minutes, it goes up to 30 minutes if you lose a trip,” she said.

RTD officials weren’t sure when regular service is likely to resume, citing the snow storm and advising residents seeking transit to check agency alerts before leaving home.

“We’re working to cover the service as best as we can,” Haberman said.

RTD officials encouraged residents to use the agency’s Next Ride web app for planning trips and checking bus and train locations. Riders also can sign up to receive alerts for service changes on specific routes.