1 1 ▁classification ▁was ▁retained ▁on ▁the ▁South ▁African ▁Rail ways ▁( S AR ). ▁ ▁The ▁ ▁Mik ado ▁type ▁was ▁rare ▁in ▁S AR ▁service , ▁the ▁Class ▁ 1 1 ▁and ▁the ▁narrow ▁gauge ▁Class ▁N G 1 5 ▁Kal ah ari ▁being ▁the ▁only ▁South ▁African ▁Mik ado ▁types ▁to ▁be ▁built ▁in ▁quantity . ▁A part ▁from ▁these , ▁the ▁S AR ▁had ▁the ▁temporary ▁use ▁on ▁le ase ▁of ▁a ▁few ▁Kat anga ▁Mik ados ▁to ▁alle vi ate ▁a ▁locomot ive ▁short age ▁during ▁the ▁First ▁World ▁War . ▁ ▁Service ▁ ▁Rail ways ▁The ▁Wit bank ▁line ▁was ▁of ▁such ▁significant ▁strateg ic ▁importance ▁that , ▁as ▁new ▁and ▁more ▁powerful ▁locomot ives ▁were ▁placed ▁in ▁service , ▁these ▁often ▁started ▁their ▁service ▁life ▁on ▁this ▁line . ▁On ▁the ▁Wit bank ▁line , ▁the ▁Class ▁ 1 1 ' s ▁loads ▁were ▁later ▁reduced ▁from ▁ ▁to ▁reduce ▁running ▁times . ▁This ▁enabled ▁them ▁to ▁run ▁the ▁double ▁trip ▁of ▁ ▁in ▁each ▁direction . ▁When ▁increased ▁traffic ▁between ▁Wit bank ▁and ▁Germ ist on ▁and ▁the ▁consequ ent ▁con g estion ▁began ▁to ▁cause ▁considerable ▁det ention ▁en - route ▁which ▁im posed ▁excess ive ▁hours ▁of ▁duty ▁on ▁the ▁train men , ▁the ▁ ▁began ▁to ▁be ▁replaced ▁by ▁Mal let ▁type ▁locomot ives ▁capable ▁of ▁handling ▁loads ▁of ▁ ▁at ▁an ▁average ▁speed ▁of ▁. ▁On ▁the ▁Mal lets , ▁the ▁train men ▁once ▁again ▁worked ▁single ▁tri ps ▁only .