 The branch from Bulle to Broc was opened on 24 June 1912 to serve not only the village but the Cailler (now Nestlé) chocolate factory.The gradients in the line are not severe with a maximum of 1 in 31 on the main line; however, the section between Broc village and Broc Fabrique has a gradient of 1 in 20 descent to the valley floor to reach the chocolate factory.These lines, operated by electric traction from the beginning, were run by the Chemins de fer électriques de la Gruyère, CEG, a company which, in 1942, joined with the two standard-gauge lines to form the GFM.