▁for ▁this ▁reason , ▁the ▁design ▁is ▁not ▁fail - safe . ▁At ▁no ▁point ▁can ▁the ▁A TC ▁system ▁override ▁the ▁maximum ▁speed ▁limit ▁enfor ced ▁by ▁the ▁cab ▁signal ▁system . ▁ ▁Autom atic ▁Train ▁Operation ▁controls ▁trains ▁so ▁that , ▁between ▁stations , ▁they ▁will ▁move ▁at ▁the ▁speed ▁specified ▁by ▁the ▁automatic ▁train ▁protection ▁and ▁automatic ▁train ▁super vision ▁sub - system s . ▁All ▁Metro ▁trains ▁are ▁man ned ▁by ▁train ▁operators ▁who ▁work ▁the ▁doors , ▁make ▁station ▁announ c ements , ▁and ▁super v ise ▁the ▁train . ▁The ▁train ▁operator ▁also ▁can ▁control ▁whether ▁the ▁train ▁oper ates ▁in ▁automatic ▁mode ▁or ▁manual ▁mode . ▁From ▁November ▁ 1 7 , ▁ 1 9 9 5 ▁until ▁January ▁ 6 , ▁ 1 9 9 6 , ▁Metro ▁management ▁required ▁its ▁employees ▁to ▁use ▁the ▁automatic ▁mode ▁at ▁all ▁times . ▁During ▁the ▁Bl izz ard ▁of ▁ 1 9 9 6 , ▁however , ▁there ▁was ▁a ▁collision ▁on ▁January ▁ 6 ▁that ▁occurred ▁when ▁the ▁A TS ▁system ▁failed ▁to ▁pick ▁up ▁proper ▁instructions ▁from ▁the ▁way side ▁communication ▁system ▁during ▁a ▁snow st orm , ▁and ▁default ed ▁to ▁the ▁highest ▁speed . ▁This ▁speed ▁would ▁have ▁been ▁safe ▁during ▁dry ▁weather , ▁but ▁because ▁of ▁ice ▁or ▁snow , ▁trains ▁required ▁additional ▁stopping ▁distance , ▁which ▁was ▁not ▁provided ▁for ▁by ▁the ▁A TC ▁system . ▁From ▁the ▁June ▁ 2 0 0 9 ▁collision ▁until ▁ 2 0 1 5