In order to implement highly automated rail operations on the 23-km-long section of the S21 line, trackside infrastructure has also been upgraded for the new European standard, ATO over ETCS. Like the upgrades to the train fleet, the use of ATO over ETCS is also a first for Germany.
The existing signal box in Bergedorf has been upgraded for ETCS operations, and an ETCS Level 2 radio block centre has also been added. In addition, balises have been installed along the track.
The upgrades were made in record time. In as early as June 2020, the upgraded signal box in Bergedorf was brought online with the additional functionality to support ETCS operations, and digital technology along the route was ready in February 2021. Since October 2020, the trains have been running at night on Hamburg's S-Bahn network to test every part of the system.