Construction of the tunnel started in January 1904 and it was opened on 1 October 1910. Prior to electrification, the line was operated by steam locomotives and gained a bad reputation because of its gradient and lack of adequate ventilation. On 4 October 1926, a steam hauled freight train stalled whilst attempting to climb the gradient in the tunnel, due the poor quality of the briquettes that were being used as fuel. Despite attempts to rescue the train crew, a total of nine railway employees died of carbon monoxide poisoning, including three of the rescuers. As a consequence, the line was electrified in 1927.