Amazingly enough Bob, waaay back in 1975 I was witness to the driver of another semi having to brake suddenly when a car driver did something stupid in front of him, as they do! The prime-mover stopped on a railway crossing and next minute the barrier came down between the prime mover and the trailer. Quick thinking driver simply drove off the crossing, taking the barrier etc with him but getting clear before the train thundered through. Luckily the prime-mover was towing only one trailer or things could have got messy. Then about 5 years ago a multi-axle transporter got grounded as it was  driven over a mounded rail crossing in Brisbane. The prime-mover had no weight on the drive, so couldn't move before a train wiped it out. Not much fun! Cheers