On 22 June 2005 a short circuit on a long distance power transmission line in central Switzerland led to a chain reaction. The entire Swiss railway network was out of service during rush hour and an estimated 200,000 people and 1,500 trains were stuck at stations or somewhere on the track. It turned out that the SBB power transmission network was overloaded and did not provide enough redundancy to tolerate the shutdown of the four cable Amsteg-Steinen power line due to construction work. So, the power grid was split in two parts, the northern half being overloaded and the southern half having a load reduction for the SBB power plants are situated in the southern part (the Alps), while most of the power is needed in the northern part (the Swiss plateau). The situation led to high voltage fluctuations and finally breakdown and emergency shutdown of the entire power supply.