The Swiss Federal Railways has blamed a short circuit on one of its power lines for the massive outage that paralysed its entire network on Wednesday evening.
The company admitted the breakdown was due partly to structural weaknesses in its electrical grid.
The short circuit happened on a power line in central Switzerland, leading to a four-hour failure. With no back-up lines available because of construction work, all the current generated by the company’s power stations north of the Gotthard Pass was diverted south to Ticino.
This in turn led to an overload of the local grid, and the automatic shutdown of the power stations. With no output from central Switzerland, the entire rail network was faced with a power shortfall and trains ground to a halt shortly before 6pm.
Technicians immediately began seeking the cause of the breakdown. While they have identified where the short circuit took place, they do not yet know why it happened.
Power was returned to the entire grid at 9:30pm. According to Federal Railways, there was no major damage to its rolling stock or infrastructures.
Trains were generally running to schedule on Thursday morning, but some services were cancelled and trains were not all in their usual configuration.
The railways’ director, Benedikt Weibel, said he had been surprised by the size of the breakdown, but he admitted that the company’s electrical grid suffered from structural weaknesses.
These weaknesses include a limited number of interconnections between the power lines and not enough substations where current can be introduced into the grid.
The lack of interconnections has been criticised in the past, after power failures in 1994.
The Swiss authorities are likely to take a closer look at the power outage.
Federal Transport Office spokesman Gregor Saladin said the railways could expect some tough questions, adding that the government subsidises the railways to the tune of SFr1.5 billion ($1.18 billion) every year.
Around 200,000 passengers on 1,500 trains were left stranded by the breakdown. The majority were commuters heading home after work.
Buses replaced trains on some routes, and old diesel trains were brought back into service.
Only seven trains were stuck in tunnels and were hauled out within 90 minutes of the power outage. The last passenger train reached its final destination shortly before 4am.
Goods transport also suffered some delays. Mail was not delivered on time in some parts of the country, and Swiss Post was forced to use more than 20 trucks to make up for lost time.
Goods trains were held up, along with convoys carrying trucks through the Alps.
But Switzerland’s main retailers, Migros and Coop, said the breakdown had little noticeable effect on them.
International inter-city trains passing through Switzerland were also affected, as were train lines of some smaller Swiss railway companies.
Federal Railways said 1,000 staff were put on duty to keep passengers informed of developments on Wednesday. The company distributed 200,000 rail vouchers worth SFr3 million ($2.35 million) to compensate for the delays.
It also organised hotel rooms for 300 passengers, as well as taxi and bus rides for those needing to reach an airport.
Passengers can still obtain compensation from the railways by contacting their local station or the company directly by phone and online.
swissinfo with agencies
The Swiss Federal Railways transport 700,000 passengers with 9,000 trains every day.
There are also 2,200 daily goods trains carrying 160,000 tons of merchandise.
The Swiss rail network, including private companies, is 5,100 kilometres long, one of the densest in the world.
The Swiss are second only to the Japanese in terms of kilometres travelled on trains.
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