The history of the Solothurn–Moutier Railway (SMB)

The SMB connects the German-speaking Solothurn region with the French-speaking Bernese Jura. Between them lies an impressive natural obstacle: the Weissenstein mountain, rising to 1,280 metres. To overcome this barrier, a tunnel measuring 3.7 kilometres had to be built.

At the end of the 19th century, however, Bern pursued its own objective. It aimed to establish a connection between northern France and Italy via the border crossing at Delle, with tunnels through the Lötschberg and Simplon. At that time, both tunnels were still under construction or only in the planning stage. In the Jura region, a direct route without steep gradients was required. Bern therefore planned an 8-kilometre base tunnel through the Jura mountain range between Grenchen and Moutier.

In the end, both variants were built. Yet neither Jura railway ultimately fulfilled expectations. Hardly had the two tunnels entered service when their importance declined dramatically with the end of the First World War and the return of Alsace-Lorraine to France. The Delle border crossing and the associated Jura railway lines suddenly lost their significance for international transit traffic, as Basel and Saint-Louis became the preferred routes.

The most important structure along the entire railway line is the 3,700-metre-long Weissenstein Tunnel. Geology, water and gradients caused major challenges during both construction and maintenance. The company Albert Buss & Cie began drilling work on 28 December 1903 at the foot of the so-called Geissfluh.

As the tunnel has a continuous gradient of 18 ‰ towards the south, work also had to be carried out mainly from the southern side, near Oberdorf.

During the first six months, all drilling was done manually. In the course of 1904, experiments with drilling machines were carried out, and the machines were later permanently installed and used. Around 50 springs are located within the Weissenstein Tunnel.

No major problems regarding working conditions are known from the construction of the Weissenstein Tunnel. The work progressed calmly and steadily. The railway supervisor was required to walk through the Weissenstein Tunnel at least once every eight days together with the foreman.

Although the electrification of the railway had already been considered before construction began, those responsible ultimately decided in favour of steam operation. On 29 July 1905, three identical locomotives were ordered from the Swiss Locomotive and Machine Works (SLM). The first steam locomotive was delivered in March 1907 and, together with a first passenger coach, was placed in the newly built depot in Moutier in November of the same year.

Given the relatively short length of the SMB line, the board of directors decided to transfer operations to a neighbouring railway company. The Emmental Railway (EB) was chosen. On 12 September 1907, the operating agreement was approved by the SMB general assembly.

The opening of operations, originally planned for 1 October 1907, had to be postponed until 1 August 1908 because the condition of the infrastructure and track did not allow an earlier start. The official inauguration ceremonies took place on Monday, 3 August 1908.

For daily passenger transport, one steam locomotive with one BC, one C and one BCFZ carriage was sufficient. The second locomotive was used for freight transport, while the third served as a reserve for operations and maintenance.

Traffic developed very positively during the first years. Due to the considerable increase in freight transport, the purchase of a powerful Ec 4/5 tender steam locomotive from SLM Winterthur was approved in 1910.

Military transport and the transport of pig iron to Von Roll Gerlafingen became important pillars of freight traffic. In passenger transport, both excursion and commuter traffic played a significant role. For this reason, the timetable was already improved in 1911.

The outbreak of the First World War had a dramatic and harmful effect on the entire transport sector and therefore also on the SMB. The enormous decline in Swiss freight traffic even led to the suspension of regular freight trains on the SMB line. These were difficult years for the company, including after the end of the war. Traffic volumes only began to improve again from 1922 onwards. However, by 1926, competition from road transport was already becoming noticeable.

A real recovery only came with the electrification of the line. Through operational cooperation with the EB and BTB, rolling stock could now be used more flexibly and operations became significantly more efficient.

The Second World War once again brought difficult years for the SMB. Even after the end of the war in Europe and overseas, damage abroad and the resulting lack of international transport meant that freight revenues did not recover. Only the opening of the chairlift to the Weissenstein in 1952 gave a strong boost to SMB excursion traffic.

At the start of operations, the SMB steam locomotive fleet consisted of three locomotives, and from 1911 onwards of four. Three of the four engines still exist today. The only steam locomotive to have been scrapped so far is number 3, which was sold to the Bulle–Romont Railway (BR) and transported to Belgium as scrap metal in 1953.

The Ed 3/4 locomotive number 1 was sold in 1934 to the Dreispitz administration in Basel (as number 6 “Ruchfeld”), transferred in 1945 to Lonza in Visp (as number 1), and from 1965 reserved for the Technorama museum in Winterthur. Since 1972, the locomotive has been stored in a depot of the DVZO steam railway association in the Zurich Oberland, awaiting restoration.

Locomotive number 2 was transferred in 1932 to the Zurich gasworks (also as number 2), and from there in 1946 to HOVAG in Ems, where it again carried number 2. In 1973, the locomotive was sold to private owners in Langenthal and today remains operational with the Dampflokfreunde Langenthal association. During the anniversary celebrations on 4 October 2008, it hauled the train from Burgdorf via Solothurn to Oberdorf and then operated shuttle journeys back to Solothurn.

The Ec 4/5 number 11 was built by SLM as a powerful superheated twin-cylinder 1'D tank locomotive. From the beginning, the SMB was very satisfied with its performance. It made it possible to almost double train weights on the steep gradients of 25 and 28 ‰. At the Moutier depot, the locomotive always received preferential treatment.

During the steam era, only specially assigned drivers operated the Ec 4/5 11. The reason probably lay in the technical particularities of the locomotive, including the Riggenbach back-pressure brake and its unusually high boiler position. The locomotive completed its last regular service in 1932. In 1958, it pulled the special train celebrating the 50th anniversary of the SMB. In 1967, it was placed as a monument in Oberburg.

Nineteen years later, it was transferred by the Dampfbahn Bern association to the Burgdorf depot, then in 1992 transported to Meiningen in Germany, where it underwent a complete restoration at the former East German railway repair works. The acceptance run between Burgdorf and Solothurn took place successfully on 18 November 1992. Since then, the locomotive has been available to the Dampfbahn Bern association for special excursions. This locomotive also participated in the anniversary celebrations, hauling the train to Oberdorf together with the Ed 3/4 2 in double traction.

In 1932, two Be 4/4 locomotives were delivered, carrying the numbers 107 and 108. In 1962, these numbers were changed to 171 and 172. The Be 4/4 locomotives could be used universally for both passenger and freight transport and proved highly reliable throughout their 70 years of service. The neighbouring railways EB and BTB, as well as the Bodensee–Toggenburg Railway, also purchased locomotives of the same type.

Locomotive number 171 was restored by RM in 1999 as a historic locomotive and sold to Swisstrain SA in 2006. At present, the locomotive is housed in the Burgdorf depot of the Dampfbahn Bern association. This typical RM locomotive also participated in the anniversary celebrations on 4 October 2008, assisting the steam locomotives as a banking engine on the route from Burgdorf to Oberdorf before later operating as a shuttle train between Oberdorf and Solothurn. Its sister locomotive was scrapped in November 2000.

In 1983, SMB ordered and commissioned a Re 4/4 locomotive numbered 181 from SLM/BBC. Following the separation of RM’s freight division, the locomotive, now redesignated Re 436 115, was transferred to Crossrail in 2006.

The operating partnership with the EBT and the VHB – under the joint management of the EBT as the largest of the three companies – was ultimately merged on 1 January 1997 into the company Regionalverkehr Mittelland (RM). RM itself then legally merged with BLS Lötschbergbahn (BLS) on 27 June 2006 to form BLS Ltd.

Since the timetable change in December 2010, passenger trains on the line, which remains owned by BLS, have been operated by SBB. This took place – together with the transfer of regional train services between Murten and Payerne – in exchange for BLS taking over SBB services in the Lucerne region.