▁in ▁ 1 8 8 6 ▁to ▁design ▁and ▁build ▁the ▁St . ▁Cla ir ▁T unnel ▁between ▁S arn ia ▁in ▁Ontario ▁and ▁Port ▁Hur on , ▁Michigan . ▁The ▁tunnel ▁was ▁constructed ▁within ▁a ▁year ▁and ▁the ▁first ▁trains ▁ran ▁through ▁in ▁the ▁later ▁part ▁of ▁ 1 8 9 1 . ▁It ▁was ▁then ▁the ▁first ▁under se a ▁tunnel ▁linking ▁two ▁distinct ▁countries , ▁and ▁the ▁longest ▁then ▁constructed , ▁at ▁ 6 , 0 2 5 ▁feet ▁portal ▁to ▁portal . ▁Total ▁length ▁of ▁the ▁tunnel ▁counting ▁the ▁approaches ▁was ▁ 1 1 , 5 0 0 ▁feet . ▁The ▁cost ▁was ▁over ▁$ 2 . 5 ▁million . ▁After ▁this ▁project ▁Hob son ▁became ▁chief ▁engineer ▁for ▁the ▁entire ▁Grand ▁Tr unk ▁Railway ▁in ▁ 1 8 9 6 . ▁The ▁tunnel ▁was ▁converted ▁to ▁run ▁electric ▁trains ▁in ▁ 1 9 0 8 . ▁ ▁Ret irement ▁and ▁death ▁ ▁Hob son ▁retired ▁from ▁the ▁railway ▁industry ▁in ▁ 1 9 0 7 . ▁He ▁was ▁a ▁railway ▁consult ant ▁until ▁his ▁death ▁in ▁ 1 9 1 7 ▁when ▁he ▁was ▁ 8 4 ▁years ▁old . ▁ ▁Soci eties ▁ ▁Hob son ▁was ▁a ▁member ▁of ▁the ▁Canadian ▁and ▁American ▁Soci eties ▁of ▁Civil ▁Engine ers ▁and ▁a ▁member ▁of ▁the ▁Institution ▁of ▁Civil ▁Engine ers ▁of ▁London , ▁England . ▁He ▁also ▁was ▁a ▁member ▁in ▁the ▁C aled on ▁Mountain ▁Tr out ▁Club . ▁ ▁Family ▁ ▁Hob son ▁married ▁Elizabeth ▁La