▁tw enti eth ▁that ▁of ▁the ▁Th ames ▁T unnel   – ▁enabled ▁faster ▁progress . ▁S cre w ▁j acks ▁drove ▁the ▁shield ▁forward ▁at ▁a ▁rate ▁of ▁ ▁each ▁week . ▁The ▁under - river ▁section ▁was ▁d ug ▁in ▁four teen ▁weeks ▁and ▁the ▁tunnel ▁completed ▁in ▁December . ▁ ▁C able ▁railway ▁▁ ▁The ▁entrance ▁sh aft s ▁were ▁fitted ▁with ▁steam - power ed ▁lif ts ▁for ▁passengers . ▁The ▁tunnel ▁was ▁laid ▁with ▁ ▁gauge ▁railway ▁track ▁and ▁a ▁single ▁car , ▁carrying ▁a ▁maximum ▁of ▁ 1 2 ▁passengers , ▁cable - h au led ▁by ▁two ▁ ▁station ary ▁steam ▁engines , ▁one ▁on ▁each ▁side ▁of ▁the ▁river . ▁The ▁under ground ▁railway ▁opened ▁on ▁ 2 ▁August ▁ 1 8 7 0 ▁charg ing ▁ 2 d ▁for ▁first ▁class ▁and ▁ 1 d ▁for ▁second ▁class , ▁first ▁class ▁ticket ▁hold ers ▁merely ▁having ▁priority ▁when ▁board ing . ▁However , ▁the ▁system ▁was ▁un re li able ▁and ▁une conom ic , ▁and ▁closed ▁that ▁December ▁after ▁the ▁company ▁went ▁bank rupt . ▁The ▁City ▁and ▁South ▁London ▁Railway ▁( C & SL ) ▁was ▁originally ▁designed ▁for ▁cable ▁ha ul age , ▁like ▁the ▁Tower ▁Sub way , ▁but ▁the ▁unexpected ▁dissol ution ▁of ▁the ▁cable ▁contract or ▁( the ▁Pat ent ▁C able ▁Tr am way ▁Corporation ) ▁precip itated ▁a ▁change ▁to ▁electric ity . ▁Its ▁generating ▁power ▁station ▁was ▁built ▁at ▁Stock well , ▁and ▁the ▁system