▁ann ually . ▁The ▁economic ▁recovery ▁after ▁ 1 9 2 4 ▁made ▁possible ▁the ▁expansion ▁of ▁its ▁network ▁to ▁neighbour ing ▁towns ▁like ▁Kn iel ingen ▁( 1 9 2 5 ), ▁D ax land en ▁( 1 9 2 8 ) ▁and ▁R int heim ▁( 1 9 2 9 ). ▁Also ▁in ▁ 1 9 2 9 , ▁the ▁newly ▁opened ▁out door ▁sw imming ▁pool ▁of ▁Rhein str and bad ▁on ▁the ▁island ▁of ▁R appen w ört ▁was ▁connected ▁to ▁Kar ls ru he . ▁This ▁line ▁operated ▁until ▁ 1 9 9 7 , ▁but , ▁due ▁to ▁the ▁lack ▁of ▁housing ▁on ▁the ▁line , ▁only ▁during ▁the ▁summer ▁bath ing ▁season . ▁The ▁Great ▁De pression ▁made ▁further ▁route ▁expansion ▁in ▁those ▁years ▁impossible . ▁Pass enger ▁numbers ▁fell ▁and ▁the ▁def ic it ▁rose . ▁As ▁a ▁result , ▁attempts ▁were ▁made ▁to ▁econom ise ▁through ▁the ▁use ▁of ▁tra ilers ▁instead ▁of ▁additional ▁tr ams . ▁ ▁The ▁tram way ▁was ▁affected ▁by ▁the ▁Second ▁World ▁War . ▁At ▁first , ▁the ▁main ▁effects ▁of ▁the ▁war ▁were ▁the ▁lack ▁of ▁staff ▁and ▁materials , ▁so ▁that , ▁as ▁in ▁the ▁First ▁World ▁War , ▁women ▁were ▁employed ▁as ▁conduct ors ▁and ▁drivers , ▁while ▁the ▁work force ▁was ▁male ▁only ▁during ▁pe ac etime ▁until ▁the ▁early ▁ 1 9 9 0 s . ▁Black out ▁measures ▁were ▁taken ▁as ▁a ▁protection ▁against ▁air ▁ra ids : ▁head light s ▁and ▁windows