▁ 2 0 0 6 , ▁the ▁Dublin ▁Metro ▁is ▁a ▁planned ▁two - line ▁rapid ▁trans it ▁( under ground ) ▁system ▁set ▁out ▁in ▁the ▁Irish ▁government ' s ▁ 2 0 0 5 ▁Transport ▁ 2 1 ▁plan ▁to ▁spend ▁ 2 0 ▁billion ▁euro ▁on ▁infrastr ucture ▁in ▁the ▁Gre ater ▁Dublin ▁area ▁up ▁until ▁ 2 0 2 1 . ▁The ▁estimated ▁cost ▁of ▁the ▁ 1 7   km ▁Metro ▁North ▁is ▁approximately ▁ 5 ▁billion ▁euro ▁and ▁will ▁be ▁the ▁biggest ▁and ▁most ▁expensive ▁infrastr uct ural ▁project ▁ever ▁undert aken ▁on ▁the ▁island ▁of ▁Ireland . ▁ ▁C ork ▁ ▁The ▁Gre ater ▁C ork ▁area ▁has ▁a ▁population ▁of ▁ 4 0 0 , 0 0 0 ▁and ▁is ▁covered ▁mainly ▁by ▁bus ▁and ▁sub urban ▁rail ▁networks ▁as ▁well ▁as ▁a ▁comm uter ▁fer ry . ▁ ▁There ▁are ▁a ▁total ▁of ▁ 3 5 ▁bus ▁routes ▁of ▁which , ▁ 1 8 ▁are ▁City bus ▁routes ▁serving ▁areas ▁like ▁C ork ▁City , ▁Kno ck na he eny , ▁Ball in l ough , ▁C ork , ▁Mah on , ▁C ork , ▁May field , ▁C ork , ▁Frank field , ▁C ork , ▁Ball int em ple ▁and ▁Far ran ree , ▁C ork ▁and ▁ 1 7 ▁sub urban ▁routes ▁serving ▁towns ▁such ▁as ▁G lan m ire , ▁Ball in col lig , ▁Car rig al ine , ▁Douglas , ▁Mid leton , ▁M allow , ▁Cob h