A collision between a big rig and a Caltrain in San Bruno late Monday afternoon disrupted service during the peak of the evening commute.

The accident happened at a construction site along Angus Avenue. The signs in the area -- reading "No Trucks" and "Clearance 11 feet 6 inches" -- couldn't be more clear.

Somehow the driver missed those signs. The train slammed into the trailer of the big rig near the San Bruno train station.

The trailer box from the truck wedged between the locomotive and cement wall of a new construction project.

"The driver realized his vehicle was too tall to get under the overpass, explained Caltrain pokeswoman Christine Dunn. "So at that point, he attempted to back up and unfortunately he was blocked in by a string of cars. So at that point he was struck by the train."

The good news was there were no injuries in the accident. But the locomotive was heavily damaged.

Trains had to single track around the accident site, causing delays of at least a half an hour during the evening commute.

"I could see the southbound was delayed heavily, but the northbound appeared to be ok and they just kept us on the train for a few minutes in Millbrae, said Burlingame resident and Caltrain commuter Darren Atkinson. "It was ok. I've had worse on Caltrain."

Cara Phillipps of Palo Alto said she was trying to make it to a work meeting.

"I'll just be late. That's how it works," said Phillipps. But I still prefer a train over a car any day."

Caltrain is spending $147 million to raise train overpasses on three streets in San Bruno to allow more clearance for vehicles passing under the tracks.

San Mateo County Sheriff's deputies are investigating the accident. There was no word Monday night on what charges -- if any -- the driver will face.

Caltrain wants to remind drivers to make sure they leave plenty of space in front of them at train crossings, so if they have to turn around, they can.