▁were ▁vertical ▁steel ▁section ▁pan els ▁and ▁Al form ▁Be am ▁wal ers , ▁which ▁were ▁attached ▁to ▁the ▁top ▁sl ab ▁of ▁the ▁special ▁steel ▁trav eller , ▁while ▁the ▁outer ▁shut ters ▁were ▁c rane ▁handled ▁vertical ▁steel ▁section ▁pan els ▁with ▁Al form ▁Be am ▁or ▁steel ▁channel ▁wal ers . ▁ ▁The ▁open ▁top ▁boat ▁unit , ▁meas uring ▁appro x ▁ 4 0 ▁metres ▁wide ▁( including ▁two ▁ 7 . 2 - met re ▁wings ▁at ▁its ▁wid est ▁point ), ▁ 1 2 0 ▁metres ▁long , ▁and ▁up ▁to ▁ 1 0 ▁metres ▁high , ▁was ▁cast ▁in ▁two ▁operations ▁using ▁standard ▁form work . ▁The ▁boat ▁unit ▁and ▁all ▁the ▁tunnel ▁section ▁elements ▁were ▁cast ▁using ▁grade ▁ 4 0 N ▁concrete ▁with ▁a ▁percentage ▁of ▁gg bf s ▁c ement ▁replacement , ▁rein for cement ▁being ▁high ▁strength ▁and ▁ 1 6 ▁to ▁ 4 0   mm ▁diameter . ▁ ▁T unnel ▁operation ▁ ▁The ▁tunnel ▁is ▁currently ▁operated ▁and ▁maintained ▁by ▁Eg is ▁Road ▁and ▁T unnel ▁Operation ▁on ▁beh alf ▁of ▁Transport ▁In frastr ucture ▁Ireland . ▁Eg is ▁took ▁on ▁that ▁role ▁in ▁ 2 0 1 5 . ▁Prior ▁to ▁that ▁it ▁had ▁been ▁operated ▁by ▁C ork ▁City ▁Council . ▁ ▁The ▁road ▁surface ▁was ▁laid ▁in ▁ 1 9 9 8 / 1 9 9 9 ▁and ▁the ▁tunnel ▁opened ▁for ▁traffic ▁on ▁ 2 1 ▁May ▁ 1 9 9 9 , ▁roughly ▁ 2