**Group of workers in front of the completed south portal of the Hauenstein base tunnel.** SBB Historic

A major project in tumultuous times

The Hauenstein base tunnel was opened in January 1916. In the middle of World War I. The story of a trailblazing feat of engineering, achieved in tumultuous times.

Marc Ribeli

Marc Ribeli is a historian and is responsible for the photo, film and video archives at SBB Historic.

Even after the creation of the first Jura tunnel in 1858, the Hauenstein was still a ‘pioneer mountain’. Around 100 years ago, the SBB built the country’s first base tunnel there. A significant increase in traffic and difficulties on the steep mountain route increased the SBB’s interest in a flat railway line. It was thought this would also improve the connection to the Gotthard and Simplon Alpine tunnels. The project proposing to lay the railway line from Sissach via Gelterkinden to Olten, and the construction of a base tunnel, was approved by the Federal Council in November 1910. This process decided on the route the new section would run, and the arguments about other project variants fell silent. However, the awarding of the contract gave rise to a whole new set of discussions. The call for tenders of May 1911 comprised the building of the tunnel, the railway line between Gelterkinden and Olten, and the construction of a new bridge over the Aare. Companies from Switzerland, Germany and France submitted bids for this work.

**Illustration of the two Hauenstein lines.** From: Wiesmann, Der Bau des Hauenstein-Basistunnels (Construction of the Hauenstein Base Tunnel), Berlin/Bern, 1917.

Unsurprisingly, the SBB favoured the cheapest offer, submitted by the Berlin construction company Julius Berger Tiefbau AG. This led to objections, particularly from the overlooked Basel firm Buss AG. Shortly before the meeting at which the award was ultimately to be decided, Buss AG contacted the SBB management and attempted to procure a review of the decision: ‘It seems to us that the Federal Railways do not adequately appreciate the disadvantageous situation in which the Swiss industry finds itself today. […] What is to become of our Swiss construction sector when, in our own country, even the national authorities award such large-scale works to foreign bidders?’ The Bundesbahnen tersely countered that the firm Buss had on many occasions received major jobs abroad. The cost difference of four million was critical. After long debate, a majority decision went in favour of Julius Berger AG.

**Workers in the bottom drift.** SBB Historic

In December 1911 the contract was signed. The company undertook to achieve hole-through on 13 January 1916, and completion on 13 January 1917. The contract provided that a penalty of 500 francs per day was payable in the event of delays, and a bonus of 300 francs was promised for completion ahead of schedule. Against the backdrop of these arrangements, the tunnel construction proceeded rapidly. The ground-breaking took place on 31 January 1912, and on the following day construction work began with the excavation of the pre-cut at the south portal and the building of the bottom drift. Initially, hand-operated augers were used; later on, mechanical compressors were able to be brought in. On average, daily progress in March 1912 was just under 5 metres per day. At the end of March, three eight-hour shifts were introduced for all tunnel workers. Work on the north side started eight months later, as the plan was to do most of the tunnelling work from the south. Hole-through was achieved on 10 July 1914, at 10:50 in the morning. Eighteen months before the contractual date! To celebrate the hole-through, all workers received a medal, a bonus payment and a paid day off work. Prominent guests including the envoy of the German Emperor and the Italian envoy attended the celebration.

**Article in ‘Schweizer Illustrierte’ magazine, July 1914.** Swissdox

But the construction work was plagued with problems. In particular, significant water ingress meant that some of the pump systems installed were working at the limit of their capacity. The tunnel workers endured great hardship. On the north side, some of the work had to be halted entirely. The work was also thrown into some disarray by the outbreak of World War I on 1 August 1914. As a result of the mobilisation ordered throughout most of Europe, many workers were called back to their own countries, while others left of their own accord. The outbreak of war meant that the work was severely restricted due to financial concerns. The SBB tried to mitigate the impact of the tunnel workers’ departure by bringing in navvies. Ultimately, the tunnel was completed on 2 May 1915 in a remarkable construction time of just over three years. The 8,135-metre-long tunnel was put into operation on 8 January 1916. Because there was a war on, it was decided not to hold a celebratory event.

**Soldiers in the worker’s village of Tripoli, 1914.** SBB Historic

Although the tunnel did have to undergo some remedial works a short time after being brought into operation, the structure can be described as an enduring piece of work. It is still one of the busiest railway tunnels in Switzerland. The resulting impacts on the landscape and the population were just as lasting. The most visible were the workers’ housing settlements, created by the influx of workers to the major new construction site. At Tecknau on the north portal, the population increased by almost 1,000 people during the construction phase, and scores of barrack-style huts, inns and other accommodation facilities were built. A workers’ village, which the mostly Italian residents called Tripoli, was also built near Trimbach at the south portal.

**The workers' village of Tripoli at the south portal of the Hauenstein Base Tunnel, around 1915.** SBB Historic

**The excavated material was used to fill up the Aare. The picture was taken around 1915.** SBB Historic

The landscape altered dramatically due to the accumulation of material excavated from the tunnel. To the north of Olten, the course of the Aare was straightened using this material, and some tributaries of the river were filled in. The Tannwald area north of Olten railway station was backfilled with excavated material, and the area was later used to extend the main SBB workshop in Olten. The large-scale project also had a detrimental impact on the water supply of communities in the immediate vicinity of the tunnel. The impairment of water rights manifested itself in situations such as stagnant wells, leading to court cases and claims for compensation.

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