Operations commenced through the tunnel on 19 May 1906.
Because of its length among other things, it has operated with electric traction rather than steam from the beginning.
The official decision to use electricity was made only half a year before its opening by the then-still-new SBB.
Brown, Boveri & Cie (BBC) were commissioned to carry out the electrification.
They decided in 1904 to use the three-phase system being introduced in Italy, with a three-phase power supply of 3,400 volts at 15.8 Hz using two overhead wires with the track acting as the third conductor.
BBC had no electric locomotives and initially acquired three locomotives built for the Ferrovia della Valtellina—the owner of the lines from Colico to Chiavenna and Tirano, which had been electrified with this system in 1901 and 1902—from their owner, the Rete Adriatica  (Adriatic Network) railway company.
These three locomotives (which became FS Class E.360) hauled all traffic through the tunnel until 1908.
On 2 March 1930, the Simplon tunnel was converted to 15 kV, 16.7 Hz AC (single-phase).
Operations commenced through the tunnel on 19 May 1906. Because of its length among other things, it has operated with electric traction rather than steam from the beginning. The official decision to use electricity was made only half a year before its opening by the then-still-new SBB. Brown, Boveri & Cie (BBC) were commissioned to carry out the electrification. They decided in 1904 to use the three-phase system being introduced in Italy, with a three-phase power supply of 3,400 volts at 15.8 Hz using two overhead wires with the track acting as the third conductor. BBC had no electric locomotives and initially acquired three locomotives built for the Ferrovia della Valtellina—the owner of the lines from Colico to Chiavenna and Tirano, which had been electrified with this system in 1901 and 1902—from their owner, the Rete Adriatica  (Adriatic Network) railway company. These three locomotives (which became FS Class E.360) hauled all traffic through the tunnel until 1908. On 2 March 1930, the Simplon tunnel was converted to 15 kV, 16.7 Hz AC (single-phase).
Simplon Tunnel