▁the ▁re vised ▁plans ▁dropped ▁the ▁D ART ▁Under ground ▁scheme ▁in ▁favour ▁of ▁these ▁existing ▁lines . ▁Having ▁previously ▁secured ▁planning ▁consent , ▁the ▁project ▁was ▁initially ▁de ferred ▁until ▁after ▁ 2 0 1 6 , ▁and ▁by ▁ 2 0 1 5 , ▁it ▁had ▁been ▁announced ▁that ▁the ▁project ▁would ▁be ▁red raft ed ▁to ▁a ▁lower ▁cost ▁design . ▁In ▁October ▁ 2 0 1 6 , ▁a ▁" scale d ▁down " ▁plan ▁was ▁published ▁with ▁a ▁potential ▁comm enc ement ▁date ▁" in ▁ 2 0 2 0 ". ▁As ▁of ▁September ▁ 2 0 1 7 ▁however , ▁it ▁was ▁suggested ▁that ▁the ▁develop ments ▁would ▁be ▁de ferred ▁until ▁after ▁ 2 0 3 0 , ▁with ▁the ▁National ▁Transport ▁Author ity ▁undert aking ▁a ▁review ▁of ▁the ▁project ▁and ▁its ▁route ; ▁this ▁review ▁project ed ▁to ▁complete ▁som etime ▁between ▁ 2 0 1 8 ▁and ▁ 2 0 2 7 . ▁ ▁History ▁D ART ▁Under ground ▁was ▁first ▁proposed ▁in ▁ 1 9 7 2 ▁in ▁the ▁" Transport ation ▁in ▁Dublin " ▁study ▁conducted ▁by ▁An ▁For as ▁For bar tha , ▁an ▁ante ced ing ▁body ▁to ▁For f ás ▁( s ometimes ▁err one ously ▁referred ▁to ▁as ▁the ▁' D ub lin ▁Transport ation ▁Study ') ▁as ▁an ▁under ground ▁rail ▁link ▁to ▁connect ▁Dublin ' s ▁three ▁main ▁railway ▁stations . ▁ ▁In ▁ 1 9 7 5 ▁CI É ▁commission ed ▁the ▁Dublin ▁Rap