Example safety barrier systems for vehicle loading docks comprise a retractable flexible barrier with a special powered latching mechanism that locks the barrier in place and prevents it from being retracted under certain hazardous dock conditions. In some examples, the barrier cannot be retracted when there is no vehicle at the dock while the dock's door is open. In some examples, an alarm is energized when concurrently the door is open, the barrier is retracted and there is no vehicle at the dock.