Portrait STI
Trolleybus No. 3 towing a post trailer through Oberhofen
In 1913, the first part of the tramway along the right shore of Thunersee was opened and the whole route between Steffisburg and Interlaken was in operation by summer 1914. The tramline that set its operators name Verkehrsbetriebe Steffisburg-Thun-Interlaken (STI) was not successful from a financial point of view though. Therefore, the section between Beatenbucht and Interlaken was already closed down in 1939. Since the old tram vehicles were considered the longer the more to slow down the traffic on the badly built road, the STI decided in the late 1940ies to replace the tramway by trolleybuses. Because of this decision, the first trolleybus ran along the Thunersee On the 19th of August 1952. The last section of tramway between Thun and Steffisburg was in service until 1958 and replaced by a motor bus service afterwards.

The trolleybus line between Thun's railway station and Beatenbucht was 13.5 kilometers long and had reversing loops in Hünibach, Oberhofen, and Gunten where it was possible to end shorter services from Thun. Like the tramway before the trolleybus had unusual high operating voltage of 1100 V DC, which was part of the reasons that led to the close down of the network on the 22th of February 1982 and its replacement by motor buses.

For operating the trolleybus line, STI ordered nine trolleybuses from Berna, Ramseier&Jenzer (R&J) respectively Gangloff and SAAS. Five bus trailers and two post trailers built by Moser completed those. The two post trailers looked from the outside very similar to the regular bus trailers and were equipped as railway post offices. The trailers, which even had post number plates, were characteristic for the trolleybus network Thun-Beatenbucht because they were the only trailers of this kind in Switzerland.

Trolleybus fleet

Numbers Type In use Comments Preserved vehicles
1-9 Rigid trolleybus 1952-1982 1100 Volt operating voltage 1, 7
21-25 bus trailer 1952-1982   23
71-72 post trailer 1952-1982 Post trailer with two axles, used as railway post office 71