The Northwest Corridor Express Lanes are a hit with many motorists. Some say they've shaved up to 45 minutes off their commute. Even those who don't use the toll lanes have benefited – traffic in the regular lanes is moving 10 to 15 miles an hour faster at rush hour.

The latest evidence the lanes have improved traffic? Some commuter buses are arriving at their destinations too early. That’s forced the State Road and Tollway Authority to change schedules for some of its Xpress bus routes.

Chris Tomlinson, SRTA's executive director, told The Atlanta Journal-Constitution recently that buses are arriving at their destinations about 15 minutes early since the Northwest Corridor lanes opened last September on I-75 and I-575 in Cobb and Cherokee counties.

“The schedules are wrong now,” Tomlinson told the AJC’s editorial board.

It’s a high-quality problem. But it has forced SRTA to adjust its schedules. Tomlinson said the agency faced a choice: keep the existing departure time and adjust the scheduled arrival time or depart 15 minutes later and arrive at the current scheduled arrival time.

Tomlinson said SRTA opted to let commuters sleep another 15 minutes by pushing back departure times.

The changes to the affected routes are among a series of Xpress bus schedule changes that will take effect Monday. You can find the schedules at www.xpressga.com.