The accident happened on the line between Holzkirchen and Rosenheim, in Bavaria. The whole line only has a single track. Trains usually cross at stations. The line is equipped with a security system that functioned normally at the time of the accident. In addition, it has been equipped with GSM-R, in 2007. In some places on the line, autonomous block signals are used to secure the track. The line is controlled by different human controllers. The control statiion responsible for the section where the accident happened is in Bad Aibling. The whole infrastructure had been checked a week before the accident, and was found to be without fault.