New bus lanes on H and I streets NW go live this morning, and that means new traffic patterns for thousands of drivers who travel along two of the District’s busiest corridors.

The new rush-hour-only lanes have been distinctively marked with red paint, have “Bus Only” markings on them and signs on each block detailing the hours of operation to make it clear to motorists to stay out of them during the morning and afternoon rush.

The red painted lanes are exclusively for buses in the morning from 7 to 9:30 a.m. and the evening from 4 to 6:30 p.m., with a few exceptions.

The I Street bus lane starts at 13th Street NW and ends at Pennsylvania Avenue NW; the H Street lane stretches from Pennsylvania Avenue NW to 14th Street NW. The lanes are part of a pilot program that will run through Sept. 27.

Bicycles, charter and school buses, as well as marked taxis, are allowed to use the lanes. Other vehicles can enter the lanes to make a right turn. But if you aren’t turning, officials warn, stay off or it could cost you.

Starting today, the city will enforce the new rules, with tow trucks nearby to haul any vehicles that park in the lanes, and police and traffic officers will ticket violators. The fine for driving or parking in the bus lanes is $200.

“While we hope that the painted red lanes and signage will deliver the message that these lanes are for buses only, we also know that it isn’t always enough,” Mayor Muriel E. Bowser (D) said Friday, in announcing the opening of the bus lanes. “We plan to be fully operational on Monday, and we will be enforcing, and that includes ticketing and towing.”

The shift frees buses from regular traffic to get people through downtown more efficiently, supporters say. More than two dozen bus routes that travel from all quadrants of the city go through H and I streets and carry about 80,000 bus rides, or about 40 percent of Metrobus rides in the District.

“Enforcement is obviously key,” said Cheryl Cort, policy director for the Coalition for Smarter Growth, which has been advocating for bus lanes. “We need to make sure the rules are clear and understandable, and we need to get to full compliance.”

That could prove to be a difficult task, especially with commercial trucks that often park in the corridor to make deliveries and view tickets as part of their business expenses. Keeping the lanes clear when drivers are still allowed to use the bus lanes as turn lanes could be difficult if traffic backs up with vehicles waiting to turn. The peak-hour restrictions could also be confusing to drivers, some advocates say.

The red paint has proved to be an effective strategy in other cities, and officials say they hope that will help Washington drivers get the message. But if that doesn’t work, officials say, tow trucks and police will be in full force.

“I think it would be better if we went to 24/7 bus lanes rather than just during the peak period, but this is a first step,” Cort said.