The Scratch City Subway Line 4 was originally branded as 1A until Line 3 was conceptinalized.It was a branch to Branch Lane.It was then extended south to East Vault and east to Cat Lane, after the remaining track between Pico Lane and Cat Lane depot to finish the ring track, and the Ring service opened with a new tunnel to the modern Cat Lane station, completing the ring. It runs on the SCS 1989 Series off the original Line 1 and 2 trains. The stations looked like the 1990 style stations of which it will get modernized. All stations have side platforms which Cat Lane will get a new island platform and a new station,Mountain East,will have an island platform only.There may be a Line 5 extension which can go further south than Line 2 and uses Line 4 tracks and stops at East Vault
Credit to all Although the trains looked a lot like the New Diamond City subway/metro trains. All SCS Stations(Excluding for lines 6,7,and 8) have PSD's Lines 1,2,and 3 already upgraded their rolling stock, making Line 4 run more frequent until it gets its own new rolling stock
