▁ 1 9 1 9 . ▁ ▁At ▁the ▁same ▁time , ▁the ▁B RT ▁moved ▁to ▁eliminate ▁remaining ▁operations ▁that ▁required ▁elev ated ▁trains ▁to ▁operate ▁under ▁overhead ▁wire . ▁In ▁most ▁cases ▁this ▁meant ▁using ▁third ▁rail ▁on ▁fully ▁grade - separ ated ▁lines . ▁When ▁third ▁rail ▁was ▁extended ▁on ▁the ▁Can ars ie ▁Line ▁it ▁was ▁decided ▁to ▁extend ▁this ▁power ▁mode ▁only ▁as ▁far ▁as ▁the ▁important ▁station ▁at ▁Rock away ▁Park way ▁and ▁Glen wood ▁Road . ▁Bey ond ▁that ▁point , ▁frequent ▁grade ▁cross ings ▁made ▁third ▁rail ▁imp ract ical . ▁This ▁portion ▁of ▁the ▁line ▁was ▁converted ▁to ▁the ▁Can ars ie ▁Sh utt le ▁using ▁elev ated ▁cars ▁in ▁October ▁ 1 9 1 7 ▁and ▁converted ▁to ▁t rol ley ▁cars ▁on ▁October ▁ 1 8 , ▁ 1 9 2 0 . ▁ ▁One ▁grade ▁crossing ▁was ▁retained ▁at ▁East ▁ 1 0 5 th ▁Street ▁despite ▁the ▁third ▁rail , ▁and ▁was ▁the ▁last ▁public ▁rapid ▁trans it ▁grade ▁crossing ▁in ▁New ▁York ▁City . ▁It ▁was ▁closed ▁by ▁ 1 9 7 3 ▁as ▁part ▁of ▁the ▁Fl at lands ▁Indust rial ▁Park ▁project , ▁which ▁was ▁built ▁on ▁either ▁side ▁of ▁the ▁ground - level ▁Can ars ie ▁Line . ▁A ▁ped est rian ▁over pass ▁above ▁the ▁tracks ▁was ▁built ▁to ▁replace ▁the ▁grade ▁crossing . ▁▁ 1 4 th ▁Street – E astern ▁Line ▁▁ ▁Bo oth ▁and ▁F lin n ▁was ▁awarded ▁the ▁contract ▁to