The city's video of the crash clearly shows the warning lights blinking at the crossing, but the driver still turns the rig to attempt to get to the other side of the tracks. The plan utterly fails. The front end of the truck just gets out of harm's way when the train smashes into the trailer and rips it from the rear of the vehicle.
According to the Prague Post, the accident didn't harm anyone on the train, but the truck driver had minor injuries. The incident could have been much worse because the locomotive was already slowing down for an upcoming station when it hit the trailer. This accident yet again illustrates the destruction that a train can cause when a vehicle gets in the way.