▁on ▁March ▁ 1 5 , ▁ 1 9 6 8 . ▁Const ruction ▁efforts ▁suffered ▁many ▁set back s ▁and ▁the ▁project ▁went ▁well ▁over ▁time ▁and ▁budget . ▁One ▁of ▁the ▁biggest ▁set back s ▁was ▁the ▁discovery ▁of ▁fault ▁lines ▁in ▁the ▁path ▁of ▁the ▁tunnel ▁that ▁were ▁not ▁discovered ▁during ▁the ▁pilot ▁b ores . ▁These ▁fault s ▁began ▁to ▁s lip ▁during ▁construction ▁and ▁emer gency ▁measures ▁had ▁to ▁be ▁taken ▁to ▁protect ▁the ▁t unn els ▁and ▁workers ▁from ▁cave - ins ▁and ▁col laps es . ▁A ▁total ▁of ▁nine ▁workers ▁were ▁killed ▁during ▁the ▁construction ▁of ▁both ▁b ores . ▁Further ▁comp lic ating ▁construction ▁was ▁that ▁the ▁b oring ▁machines ▁could ▁not ▁work ▁as ▁fast ▁as ▁expected ▁at ▁such ▁high ▁alt itudes , ▁and ▁the ▁product ivity ▁was ▁significantly ▁less ▁than ▁planned . ▁The ▁fr ustration ▁prompt ed ▁one ▁engineer ▁to ▁comment , ▁" We ▁were ▁going ▁by ▁the ▁book , ▁but ▁the ▁dam ned ▁mountain ▁couldn ' t ▁read ". ▁The ▁first ▁bore ▁was ▁dedicated ▁March ▁ 8 , ▁ 1 9 7 3 . ▁Initial ly ▁this ▁tunnel ▁was ▁used ▁for ▁two - way ▁traffic , ▁with ▁one ▁l ane ▁for ▁each ▁direction . ▁The ▁amount ▁of ▁traffic ▁through ▁the ▁tunnel ▁exceed ed ▁predictions , ▁and ▁efforts ▁soon ▁began ▁to ▁exped ite ▁construction ▁on ▁the ▁second ▁t ube ▁( the ▁Johnson ▁bore ), ▁which ▁was ▁finished ▁on ▁December ▁ 2 1 , ▁ 1 9 7 9 . ▁The ▁initial ▁engineering ▁cost