Buses to substitute for trams in Bonn The days of the old signal box are numbered

Bonn · For two and a half years, the central signal box for municipal transport has been undergoing conversion. Before the new signaling technology can go into operation, inspectors have to test all the functions. For this reason, buses will be running on some tram lines from August 2 to 10.

At the old control board in the operations center, Joachim Schallenberg can switch points and signals by hand.

Foto: Meike Böschemeyer

You can hear the technology from the 1970’s: The relays in the underground signal box at Bonn's central station click like metal. Before anything moves in the light rail network, one of the countless components of the system, which consists of several sections full of signaling technology, audibly clicks into place. It's quite different in the room next door: here, the new, digital interlocking technology is tucked away in narrow cabinets, accompanied only by the steady whir of fans.

At the beginning of August, Stadtwerke Bonn (SWB) will be converting to electronic technology. For Joachim Schallenberg, head of the traffic control center, and Christian Lehr, head of the signaling department, this marks the end of a two-and-a-half-year preparatory period during which the system was converted "while the wheels were rolling." "An interlocking system controls and secures all light rail vehicle movements with the help of signals, switches and barrier systems," explains Schallenberg.

In order for the new technology to go into operation, external inspectors have to carry out test runs with city trams from August 2 to 10 and approve everything. Every traffic signal, every barrier and every switch will be tested. During this time, buses will run as substitutes for individual tram lines.

The new technology has many advantages: for example, trams can be diverted to the opposite track if a defective tram is blocking the track in the regular direction of travel. Until now, such reroutes have only worked with a lot of consultation, which the team in the operations control center on Thomas-Mann-Strasse handles. With the changeover, the old signal control at the local train station has been divided into four signal boxes that are electronically interconnected. This means that operations can react much more flexibly to disruptions because only smaller sections of the network are affected at any one time.

Up to now, work on the large-scale project has been done mainly during operational pauses or shutdowns. The technical leap from 50-year-old signaling technology to electronic control can be compared to the jump from a dial-up telephone to a smartphone. So far, passengers have hardly noticed. In the tunnels, among other things, the system ensures that sufficient distance is kept between the light rail vehicles. That way, there can be no rear-end collisions there. "If a tram enters a curve too quickly or passes a red signal, it is slowed down by the signal system," Lehr explains.

The regional transport association Zweckverband Nahverkehr Rheinland is subsidizing the work with funding of between 40 and 68 percent. According to municipal utility company SWB, the total investment will be in the "mid double-digit million range". In the coming years, four more signal boxes in Bonn, Königswinter and Sankt Augustin will be successively modernized. Until then, the old facility under the main station will serve as a spare parts store. (Orig. text: Bettina Köhl / Translation: ck)