Baltimore kicked off its newest version of free downtown bus service Monday morning as the Charm City Circulators began service on its Orange Route from Hollins Market to Harbor East via downtown.

Making one of her last public appearances before her resignation takes effect next month, Mayor Sheila Dixon hailed the circulator – which uses hybrid diesel-electric buses to reduce emissions -- as a way to reduce single-operator vehicle traffic downtown.

"It's going to be cleaner and greener and it's really going to help us move downtown," she said at a news conference at the Convention Center.

Dixon, who announced her resignation last week as part of a plea bargain in a public corruption case, has been one of the chief backers of the free bus service during its bumpy journey from concept to reality.

Dixon touted the virtues of the new service, which is expected to operate the buses at 10-minute intervals seven days a week.

"You can go down to harbor East by just jumping on the circulator," she said. "This is exciting. We finally have the first line up."

The city-operated circulator is expected to add two additional routes – a Green Line and a Purple Line – this spring. The Purple Line will connect Penn Station with Federal Hill, while the Green Line will tie Hopkins Hospital with Fells Point and City Hall.

Unlike previous, short-lived versions of free downtown bus service, the circulator has a dedicated source of financing in the city's parking tax.

During the winter months, the weekday service will operate from 6:30 a.m. to 8 p.m. except for Fridays, when it will continue until midnight.

On Saturdays it will operate 9 a.m. until midnight; on Sunday the buses will run 9 a.m. to 9 p.m.

During the summer, the weekday service will be extended to 9 p.m.