ies . ▁Three ▁years ▁later , ▁the ▁city ▁centre ▁route ▁was ▁equ ipped ▁with ▁an ▁overhead ▁line ▁and ▁the ▁accum ulator ▁mode ▁was ▁abandoned , ▁so ▁that ▁all ▁cars ▁could ▁be ▁used ▁everywhere . ▁ ▁In ▁the ▁following ▁years ▁the ▁tram ▁network ▁was ▁extended ▁to ▁some ▁of ▁the ▁newly ▁created ▁sub ur bs ▁( O st stadt , ▁West stadt , ▁Süd west stadt ) ▁and ▁was ▁to ▁the ▁nearby ▁towns ▁of ▁Be ier the im . ▁However , ▁railway ▁tracks ▁significantly ▁imp eded ▁routes ▁in ▁the ▁middle ▁of ▁the ▁city , ▁so ▁not ▁all ▁proposed ▁extensions ▁could ▁be ▁implemented . ▁The ▁importance ▁of ▁the ▁tram way ▁for ▁the ▁urban ▁development ▁prompt ed ▁the ▁city ▁of ▁Kar ls ru he ▁to ▁ac quire ▁the ▁tram ▁service ▁from ▁A EG ▁in ▁ 1 9 0 3 ▁and ▁operate ▁it ▁as ▁a ▁municipal ▁undert aking . ▁Comp ared ▁to ▁the ▁period ▁of ▁horse ▁and ▁steam ▁operations , ▁the ▁expansion ▁of ▁the ▁network ▁acceler ated ▁and ▁passenger ▁traffic ▁rose ▁rapidly . ▁For ▁example , ▁in ▁ 1 9 0 1 ▁there ▁were ▁ 6 . 8 ▁million ▁passengers ▁and ▁by ▁ 1 9 1 2 ▁patron age ▁had ▁reached ▁ 1 5 . 9 ▁million ▁passengers . ▁ ▁Development ▁until ▁the ▁Second ▁World ▁War ▁The ▁development ▁of ▁the ▁Kar ls ru he ▁tram ▁network ▁at ▁the ▁beginning ▁of ▁the ▁ 2 0 th ▁century ▁was ▁affected ▁by ▁the ▁numerous ▁level ▁cross ings ▁in ▁the ▁city ▁area ▁where ▁tr ams ▁were ▁not ▁allowed ▁to ▁cross ▁over ▁rail