On 29 June 2023 it was fifty years since the first Düwag light rail vehicle of the new “B 100 S” model arrived at the Stadtwerke in Bonn with railcar 7351. It was one of three prototypes built by Düwag of the “B-Wagen”, the other two being the 2001 and 2002 vehicles of Cologne’s KVB.
First revenue service on line S
After extensive test runs and driver training, the Bonn No. 7351 went into service on the then Line S between Bonn city centre and Siegburg (today part of Line 66). Since the S was served with eight-axle trams in double traction at that time, but the B-Wagen could not be coupled with any other vehicle of the Bonn light rail fleet, it was initially only used as reinforcement service during rush hours.
The prototype in double traction
That all changed when the first seventeen production vehicles of the B-wagon arrived in Bonn a year later, in 1974 numbered 7451 to 7467, the prototype had to be adapted to the series production, so it could run as coupled pair with the additional vehicles.
The purchase of the Cologne prototypes at a bargain price was rejected by SWB some years later.
Cologne-Bonn light rail line 16
On 12 August 1978, the Cologne-Bonn light rail line 16 between Bonn Rheinallee and Cologne Wiener Platz started service as the “longest underground line in Germany” at that time. This meant that the Bonn B-Wagens now also came to Cologne, including 7351, and the Cologne B-Wagens also came to Bonn – with the exception of the two prototypes in 2001 and 2002, which were never adapted to the series in Cologne. In the beginning, the principle was that the B-Wagens of both cities should be able to be coupled together completely freely. The inaugural train of line 16 on 12 August 1978 consisted of a double traction of the Bonn No. 7751 and the Cologne No. 2004.
Cologne later purchased large numbers of light rail vehicles that could no longer be combined with the Bonn cars. This did not change again until 2003, when Cologne and Bonn jointly procured 74 railcars of the identical type Bombardier Flexity Swift (SWB No. 0361 to 0374) – they could be coupled together again.
Sale to Dortmund
When Bonn sold a larger number of older B-Wagen to Dortmund, no. 7351 was included. However, it was only used as source of spare parts and never resumed passenger operation.