SAN FRANCISCO -- For the second day in a row, a big rig's troubles affected the morning commute across the Bay Bridge.

Westbound traffic slowed to a crawl at the "S" curve and backed up rapidly after a big rig stalled in the No. 5 lane around 5:43 a.m. Tuesday morning, California Highway Patrol Officer Ron Simmons said.

Crews were still trying to get the truck off the bridge more than an hour after its brakes locked up and it came to a halt just east of the Fremont Street offramp, Simmons said. The truck, which was carrying lumber, was moved by a big-rig tow truck around 7:15 a.m., Simmons said.

Traffic was not expected to back up as badly as it had on Monday, but the metering lights at the Toll Plaza were operating with a small delay, and the commute over the bridge was taking about an hour as of 7 a.m., according to the CHP.

Adding to the difficulties, an AC Transit bus also traveling into San Francisco stalled in the No. 1 lane west of the incline just before 8 a.m. It took crews about 10 minutes to get the bus out of the lane, Simmons said.

The traffic issues came a day after another big-rig truck caught fire after blowing out a tire on the bridge near the Fifth Street exit. The driver of the truck, which was carrying food, was not injured, but motorists reported commute times over the bridge of nearly two hours as a result of that incident, and traffic was affected all of Monday.

Contact Rick Hurd at 925-945-4789 and follow him at Twitter.com/3rdERH.