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Sonnenberg bunker is drawing attention due to the war in Ukraine

01.07.2022 – STÉPHANE HERZOG

For a long time, Sonnenberg nuclear fallout shelter, inaugurated in 1976 in Lucerne and with a capacity of 20,000, was the largest facility of its kind in the world. A visit to this reminder of the Cold War takes on new significance with the return of war in Europe. Report.

Higher, further, faster, more beautiful? In search of the somewhat different Swiss records. This edition: Switzerland’s biggest nuclear bunker.

Before us is a children’s playground, on a little hill, with a sandpit and swings, surrounded by little houses. In the distance, there is a concrete gate. Welcome to Sonnenberg bunker, the largest nuclear fallout shelter ever built in Switzerland. We are one kilometre west of Lucerne train station as the crow flies, in the Bruchmatt district.

Our guide, Zora Schelbert, arrives by bike. A teacher by training, she has been taking visitors on tours of the site since 2006. It is a part-time job, “where every visit is different”. The guide from Lucerne doesn’t live far away, but as it turns out, she would have to go elsewhere if there were an attack. Where exactly? “I asked about this on a website dedicated to these questions, but I never got a reply,” she laughs. We follow a 200-metre-long sloping tunnel. On the walls, there are orange marks, 20,000 of them. The idea came from the Unterirdisch-überleben association, which organises the visits. Each mark represents a human being, who would have been allocated one square metre of living space. This crowd would have been spread between the two motorway tunnels, protected on either side by reinforced doors. This calculation forms the basis for the Sonnenberg shelter, inaugurated in 1976.

Electricity for two weeks

At the end of the corridor, we access the top of a seven-storey underground building. The building is set above the A2 motorway, on the north-south axis, where 65,000 vehicles pass each day. This is the cavern. In the event of war or a catastrophe, this concrete cylinder would have served as the headquarters and workspace for 700 members of the civil defence. Each floor has its own role. The seventh floor is dedicated to energy and ventilation, with biological, chemical and nuclear filters. The cavern has three diesel motors, including one emergency one, with enough fuel to produce electricity for two weeks. This floor also has electric winches installed vertically over the motorway. These would have allowed survival equipment – beds and toilets – to be lowered into the two tunnels. A third of the city’s population could have sought refuge here.

In Kyiv and Kharkiv, deep metro tunnels are being used as protection from bombings. In Lucerne, this 1.5-kilometre section of motorway would have served the same purpose. In 1987, the Fourmi operation revealed the inadequacies of the project, if it were to be used in reality. The aim was to lay out 10,000 bunks in one week along one of the two tunnels. But the trolleys intended for use in this situation got stuck in the corridors. More serious still, one of the four concrete doors blocking the motorway would not close properly. The decision was taken in 2002 to downsize the facility and to lower its capacity to 2,000 people, who could now be housed in 24 hours. That was the end of the motorway shelter.

Protestors locked underground

Since its inauguration in 1976, the Sonnenberg bunker has been used only once: in December 2007, when a protest was led against the closure of an alternative site. The police, who still possess a floor in Sonnenberg, locked dozens of protestors in cells adapted for this purpose. “It was as though they wanted to test the place out,” comments our guide. Four years ago, 200 new bunks were also set up on one of the floors of the cavern for refugees. The project was later abandoned.

Since the beginning of the war in Ukraine, many people have called the association for information about the bunker, something which hasn’t happened since 2006. People are making plans and want to know where they can shelter. But the question more familiar to the association that organises tours, including a descent into the bunker, is that posed by visitors from abroad: why should there be such fear of an attack in a country considered neutral? Others marvel that Switzerland would take such extensive measures to protect its citizens. But the older generation in Switzerland admit that they felt reassured by this project. As for the young visitors, the extent of the facility teaches them about the perception of the nuclear threat that reigned at the time of the Cold War. Zora Schelbert, who will mark her 1,000th visit this year, has a nuanced view of the shelter: “I don’t want to laugh at this place. Its aim was to help people, even if I have my doubts about its use,” explains the teacher.

Inhuman human density

In Sonnenberg, every visitor imagines life underground. The human density would have essentially confined each person to their bunk. They would have had to queue to access the dry toilets and the taps in their survival unit, each of which has 64 places. Each individual would have had to bring their own food. Water would have been rationed. No resources were planned for heating the food, with the only kitchens in the shelter reserved for the staff and the underground hospital, which also included a few showers – the only ones in the building. The visit passes by an operating theatre, a meeting room and a radio studio. The association has been able to preserve the atmosphere of the Cold War years, maintaining surgical materials, telephone landlines and powdered survival rations. The blocks in the cavern run one after another, each identical. The walls are mainly painted in green and yellow, colours intended to have a calming effect. A delivery room for childbirth is painted a salmon shade. The cramped space immediately makes you want to escape.

There is no chapel in Sonnenberg, but there are prison cells: enough to hold 16 individuals. In the event of an attack, tensions underground would no doubt have come to a head. In fact, it is quite possible that this was a reason for the shelter’s 'downsizing'. At the end of the hole, we can see the traffic on the A5. “Financial support from the Confederation for the creation of this facility enabled Lucerne to build this motorway at low cost,” our guide reminds us. If so required, the inhabitants of Lucerne assigned a place in Sonnenberg would have crossed the playground and headed up the service tunnel.

Reinforced concrete doors have been a familiar sight under Swiss homes for decades. Photo: Keystone

Switzerland has more than one shelter space per person

Sonnenberg bunker is part of a global system, based on a law passed in 1959. The law guarantees a shelter space for each inhabitant, accessible in 30 minutes by foot. The country has around 365,000 private and public shelters, providing approximately 9 million places. This covers more than the entire population. In recent years, approximately 50,000 places were created each year, estimates the Swiss Federal Office for Civil Protection. The owners of each new house built are supposed to create their own shelter, which they must furnish and maintain. If a house does not have a shelter, a contribution for a replacement needs to be paid. Where there are shortfalls, the municipalities have to build, furnish and maintain public shelters. Built from reinforced concrete, the Swiss bunkers are meant to resist the pressure of a bomb and reduce radiation intensity by a factor of 500.

The Swiss generally use the shelters as storage spaces or even for meeting rooms and for lodging asylum seekers or people with no fixed address. But these spaces must be made operational in five days.

On 3 March, a week after the breakout of war in Ukraine, the Confederation gave notice that in light of the security situation, the cantons would have to “review the plans for allocation of shelter and adapt as necessary”.