Its 23 km (14 mi), standard gauge line has belonged to the Swiss Federal Railways (SBB) since 1902.

Since in the second option would not have benefitted the town of St. Gallen and would have lost significant potential traffic, the Bischofszell Railway decided on the Gossau–Sulgen route.

This fact often causes problems for operations, because light locomotives like the Re 4/4I (their last domain) had to be used for freight traffic, since the Ae 6/6 were too heavy.

Today, Stadler GTW low-floor articulated railcars operate on the line.

The problem lies with the bridges between Bischofszell Nord and Hauptwil, which have a maximum permissible load per metre of 6.4 t/m, because operations are now permitted without restraint with an axle weight of 22.5 t.[2] In the past this limit was much lower.