ways ▁or ▁could ▁cross ▁only ▁with ▁restrictions . ▁Therefore , ▁some ▁of ▁the ▁desired ▁extensions , ▁for ▁example , ▁in ▁the ▁southern ▁district , ▁were ▁possible ▁only ▁with ▁the ▁re location ▁of ▁Kar ls ru he ▁station ▁in ▁ 1 9 1 3 . ▁Sub sequently , ▁the ▁tram ▁network ▁was ▁expanded ▁to ▁the ▁south . ▁However , ▁some ▁of ▁these ▁exp ans ions ▁were ▁delayed ▁by ▁the ▁First ▁World ▁War ▁until ▁ 1 9 2 1 . ▁ ▁In ▁ 1 9 1 5 , ▁the ▁Kar ls ru he ▁Local ▁Railway ▁was ▁acquired ▁by ▁the ▁city ▁of ▁Kar ls ru he ▁and ▁the ▁met re ▁gauge ▁network ▁became ▁part ▁of ▁the ▁urban ▁tram way . ▁However , ▁the ▁met re - g au ge ▁operation ▁was ▁une conom ical ▁and ▁most ▁sections ▁of ▁it ▁had ▁been ▁closed ▁down ▁by ▁ 1 9 3 8 . ▁The ▁met re - g au ge ▁operation ▁finally ▁ended ▁on ▁the ▁last ▁line ▁to ▁H ags feld ▁in ▁ 1 9 5 5 . ▁ ▁Pass enger ▁numbers ▁grew ▁stead ily ▁until ▁World ▁War ▁I ▁with ▁a ▁record ▁ 5 6 . 3 ▁million ▁in ▁ 1 9 1 9 , ▁but ▁they ▁col lapsed ▁due ▁to ▁the ▁economic ▁conditions ▁after ▁the ▁war ▁and ▁the ▁hyper infl ation ▁in ▁ 1 9 2 3 / 2 4 ▁to ▁only ▁ 2 1 ▁million . ▁By ▁ 1 9 2 5 , ▁patron age ▁recovered ▁and ▁reached ▁a ▁level ▁of ▁about ▁ 4 0 ▁million ▁passengers