▁vol ts ▁in ▁ 1 9 2 1 ▁and ▁finally ▁to ▁ 1 0 0 0 ▁vol ts ▁in ▁ 1 9 2 8 ▁with ▁the ▁replacement ▁of ▁the ▁converter ▁group ▁in ▁Spe icher ▁by ▁a ▁fully ▁automatic ▁mer cur y ▁v ap our ▁rect ifier ▁plant . ▁In ▁the ▁city ▁of ▁St . ▁G allen , ▁the ▁trains ▁ran ▁on ▁the ▁tracks ▁of ▁the ▁St . ▁G allen ▁Tr am way , ▁which ▁was ▁closed ▁in ▁ 1 9 5 7 . ▁Because ▁of ▁the ▁inter sections ▁with ▁the ▁city ▁t rol ley b uses , ▁the ▁contact ▁wire ▁voltage ▁is ▁still ▁only ▁ 6 0 0 ▁vol ts . ▁▁ ▁Despite ▁the ▁mod est ▁length ▁of ▁its ▁operations , ▁the ▁Tro gen ▁Railway ▁has ▁been ▁preserved . ▁The ▁line , ▁which ▁originally ▁ran ▁almost ▁completely ▁on ▁track ▁laid ▁on ▁roads , ▁has ▁been ▁largely ▁moved ▁over ▁the ▁years ▁to ▁its ▁own ▁route . ▁With ▁a ▁gradient ▁of ▁up ▁to ▁ 7 . 6 %, ▁the ▁Tro gen ▁Railway ▁was ▁the ▁ste ep est ▁narrow - g au ge ▁ad hes ion ▁line ▁in ▁Switzerland ▁prior ▁to ▁the ▁opening ▁of ▁the ▁R uck hal de ▁T unnel . ▁ ▁Cross - city ▁line ▁ ▁Since ▁the ▁ 1 9 7 0 s , ▁t unn els ▁between ▁St . ▁G allen ▁and ▁the ▁sub urb ▁of ▁Ri eth üs li ▁have ▁been ▁planned ▁to ▁eliminate ▁the ▁last ▁ra ck ▁section ▁between ▁St . ▁G allen ▁and ▁App enz ell . ▁All ▁these