▁urban ▁development ▁that ▁had ▁a ▁significant ▁impact ▁on ▁public ▁transport ▁and ▁so ▁also ▁for ▁Kar ls ru he . ▁This ▁involved ▁the ▁creation ▁of ▁new , ▁large ▁housing ▁est ates ▁on ▁the ▁peri ph ery ▁that ▁had ▁to ▁be ▁connected ▁to ▁the ▁city . ▁From ▁the ▁ 1 9 6 0 s , ▁there ▁has ▁been ▁increased ▁sub urban isation , ▁which ▁has ▁led ▁to ▁significant ▁growth ▁in ▁the ▁neighbour ing ▁municipal ities , ▁which ▁continues ▁to ▁date . ▁In ▁parallel ▁with ▁this ▁there ▁has ▁been ▁a ▁change ▁in ▁the ▁economic ▁structure : ▁the ▁large ▁fact ories ▁in ▁the ▁city ▁were ▁abandoned ▁and ▁new ▁industrial ▁and ▁commercial ▁areas ▁were ▁developed ▁on ▁the ▁out sk ir ts . ▁ ▁The ▁emer gence ▁of ▁mass ▁motor isation ▁led ▁to ▁increasing ▁competition ▁for ▁the ▁tr ams . ▁In ▁addition ▁the ▁increasing ▁car ▁traffic ▁led ▁to ▁increased ▁con g estion ▁on ▁the ▁tram ▁routes . ▁In ▁contrast , ▁the ▁tram way ▁network ▁in ▁the ▁early ▁ 1 9 5 0 s ▁was ▁still ▁the ▁same ▁as ▁it ▁was ▁in ▁ 1 9 3 0 . ▁The ▁difficult ▁economic ▁situation ▁of ▁the ▁ 1 9 3 0 s ▁and ▁material ▁dep riv ation ▁and ▁destruction ▁during ▁the ▁Second ▁World ▁War ▁did ▁not ▁permit ▁modern isation ▁of ▁vehicles ▁and ▁equipment . ▁ ▁Un like ▁many ▁other ▁cities ▁that ▁closed ▁their ▁tram way ▁networks , ▁Kar ls ru he ▁started ▁to ▁modern ise ▁its ▁network : ▁by ▁ 1 9 8 0 , ▁ 7 5 % ▁of ▁the ▁tracks