▁and ▁from ▁either ▁end , ▁using ▁eight ▁head ings . ▁The ▁sh aft s ▁were ▁about ▁ ▁deep ▁and ▁measured ▁about ▁ ▁by ▁. ▁The ▁ho ists ▁were ▁operated ▁using ▁horses . ▁The ▁t unn eling ▁operations ▁used ▁black ▁pow der ▁as ▁explos ive . ▁D anger ous ▁rock ▁conditions ▁at ▁the ▁east ▁end ▁of ▁the ▁tunnel ▁and ▁acc idents ▁with ▁black ▁pow der ▁caused ▁many ▁cas ual ties , ▁with ▁a ▁total ▁of ▁about ▁ 3 0 ▁death s ▁and ▁ 3 0 0 ▁inj uries ▁in ▁the ▁exc av ation ▁of ▁the ▁King wood ▁T unnel ▁and ▁the ▁contempor aneous ▁Board ▁Tree ▁T unnel ▁on ▁the ▁same ▁line . ▁ ▁Although ▁the ▁tunnel ▁itself ▁was ▁completed ▁in ▁ 1 8 5 2 , ▁track ▁was ▁not ▁laid , ▁due ▁to ▁problems ▁with ▁the ▁east ▁entrance . ▁A ▁temporary ▁switch back ▁track , ▁requiring ▁revers al ▁at ▁each ▁stage , ▁was ▁built ▁to ▁provide ▁service ▁until ▁the ▁tunnel ▁was ▁finished . ▁Work ▁began ▁in ▁ 1 8 5 4 ▁on ▁an ▁arch ed ▁l iner ▁using ▁pre fab ric ated ▁sections ▁of ▁iron , ▁faced ▁with ▁stone ▁against ▁the ▁event ual ▁d eter ior ation ▁of ▁the ▁iron ▁lin ers . ▁ ▁of ▁this ▁system ▁were ▁used ▁at ▁the ▁east ▁end , ▁and ▁another ▁ ▁of ▁the ▁tunnel ▁were ▁l ined ▁with ▁brick . ▁L ining ▁work , ▁followed ▁by ▁track ▁lay ing , ▁was ▁completed ▁in ▁ 1 8 5 8 . ▁It ▁was ▁completed ▁with ▁two ▁tracks , ▁but ▁the