0 , ▁C ork ▁Corporation ▁commission ed ▁De Le uw ▁Ch ad wick ▁O ’ h E och a , ▁engineering ▁consult ants , ▁to ▁undert ake ▁a ▁feas ibility ▁study ▁of ▁options ▁for ▁a ▁major ▁highway ▁crossing ▁of ▁the ▁River ▁Lee ▁down stream ▁from ▁C ork ▁city ▁centre . ▁A ▁team ▁led ▁by ▁J . D . ▁Sh ink win , ▁Director ▁of ▁De Le uw ▁Ch ad wick ▁O ’ h E och a , ▁performed ▁the ▁study . ▁The ▁first ▁stage ▁of ▁the ▁report ▁established ▁that ▁the ▁crossing ▁should ▁be ▁located ▁in ▁D unk ett le , ▁rather ▁than ▁at ▁T iv oli , ▁closer ▁to ▁the ▁city ▁centre . ▁ ▁The ▁second ▁stage ▁end ors ed ▁an ▁imm ers ed ▁t ube ▁tunnel ▁as ▁the ▁preferred ▁scheme ▁versus ▁a ▁bridge ▁( e ither ▁fixed ▁or ▁opening ▁span ). ▁The ▁primary ▁reasons ▁were ▁that ▁a ▁tunnel ▁would ▁have ▁a ▁lower ▁construction ▁cost ▁relative ▁to ▁its ▁utility , ▁shorter ▁approach ▁grad ients , ▁lower ▁environmental ▁impact ▁and ▁no ▁effect ▁on ▁sh ipping ▁once ▁built . ▁While ▁the ▁construction ▁costs ▁for ▁a ▁two ▁l ane ▁tunnel ▁were ▁margin ally ▁higher ▁than ▁for ▁a ▁two ▁l ane ▁high - level ▁bridge , ▁the ▁ste ep ▁up ward ▁r amp ▁for ▁a ▁high - level ▁bridge ▁would ▁slow ▁down ▁cars ▁and ▁tr uck s ▁as ▁they ▁clim bed ▁the ▁bridge , ▁thus ▁reducing ▁its ▁peak ▁capacity ▁dram atically ▁versus ▁a ▁tunnel ▁or , ▁altern atively , ▁necess it ating ▁the ▁addition ▁of ▁a ▁clim