the brühl railway station is a minor station on the double-tracked west rhine railway line. at the time of the accident it had two passing sidings, one on each side of the through lines. the station is equipped for limited bi-directional running: the passing sidings had exit signals on both ends while the through lines had exit signals only for the main direction. a train passing the station on the "wrong" line therefore had to use the passing siding rather than the main running line unless a specific written order was issued.