, ▁Met ror ail ▁operators ▁operated ▁the ▁trains ▁exclus ively ▁in ▁manual ▁mode ; ▁the ▁A TC ▁system ▁was ▁restored ▁to ▁the ▁Red ▁Line ▁in ▁ 2 0 1 5 . ▁The ▁automatic ▁train ▁protection ▁system ▁still ▁limits ▁the ▁maximum ▁speed ▁of ▁every ▁train ▁that ▁is ▁in ▁re venue ▁service . ▁ ▁An ▁autom ated ▁announ cement ▁system ▁is ▁equ ipped ▁on ▁the ▁ 7 0 0 0 - series ▁rolling ▁stock ▁and ▁is ▁planned ▁to ▁be ▁added ▁to ▁the ▁ 6 0 0 0 - series ▁rolling ▁stock ▁once ▁re h abil itation ▁of ▁those ▁train ▁cars ▁is ▁complete . ▁ ▁Non - re venue ▁tracks ▁( storage ▁tracks , ▁tail ▁tracks , ▁yard ▁tracks ) ▁are ▁not ▁equ ipped ▁with ▁A TC . ▁Green ▁signs ▁with ▁letters ▁reading ▁" START ▁A TC " ▁and ▁" END ▁A TC " ▁mark ▁the ▁beginning ▁and ▁ending ▁respectively ▁of ▁A TC ▁territory . ▁ ▁Station ▁identification ▁ ▁The ▁system ' s ▁rail ▁lines ▁run ▁on ▁eleven ▁letter ed ▁" routes ". ▁Within ▁these ▁routes , ▁each ▁station ▁is ▁also ▁identified ▁by ▁a ▁letter ▁and ▁number ▁system ▁based ▁on ▁the ▁route ▁letter ▁and ▁the ▁station ▁number ▁in ▁asc ending ▁order ▁from ▁the ▁system ' s ▁ge ographic ▁center . ▁This ▁is ▁known ▁as ▁the ▁Rem ote ▁Terminal ▁Unit ▁( RT U ) ▁number . ▁The ▁R T U ▁number ▁ident ifies ▁the ▁station ▁and ▁nearby ▁track ▁controlled ▁by ▁the ▁station ' s ▁way side ▁control ▁room ▁to ▁Metro ' s ▁Central ▁Control . ▁, ▁,