▁was ▁constructed ▁from ▁Ger ald ton ▁to ▁Car nar von ▁by ▁ 1 9 6 2 . ▁The ▁impact ▁of ▁cycl ones ▁and ▁season al ▁flo oding ▁resulted ▁in ▁a ▁real ignment ▁in land ▁of ▁the ▁Car nar von ▁to ▁Port ▁Hed land ▁section , ▁which ▁was ▁constructed ▁and ▁se aled ▁between ▁ 1 9 6 6 ▁and ▁ 1 9 7 3 , ▁and ▁required ▁thirty ▁new ▁brid ges . ▁Vari ous ▁up gr ades ▁have ▁been ▁carried ▁out ▁in ▁sections ▁across ▁the ▁length ▁of ▁the ▁highway , ▁including ▁the ▁Ger ald ton ▁Southern ▁Transport ▁Cor rid or ▁project ▁which ▁grade - separ ated ▁the ▁highway ' s ▁j unction ▁with ▁Brand ▁Highway . ▁ ▁Port ▁Hed land ▁to ▁Lake ▁Arg yle ▁ ▁Great ▁Northern ▁Highway ▁was ▁created ▁in ▁ 1 9 4 4 ▁from ▁existing ▁roads ▁in ▁the ▁Whe at b elt , ▁and ▁a ▁series ▁of ▁tracks ▁through ▁remote ▁past oral ▁areas . ▁Like ▁North ▁West ▁Coast al ▁Highway , ▁it ▁was ▁a ▁ha z ard ous ▁route ▁that ▁could ▁be ▁dust y ▁in ▁the ▁dry ▁season , ▁and ▁bog gy ▁or ▁was hed ▁away ▁in ▁the ▁wet ▁season . ▁Some ▁sections ▁were ▁effectively ▁just ▁sand , ▁while ▁others ▁contained ▁lim estone ▁out cro ps . ▁Econom ic ▁growth ▁and ▁development ▁in ▁northern ▁Western ▁Australia ▁prompt ed ▁initial ▁improvement ▁efforts , ▁and ▁the ▁federal ▁government ' s ▁Be ef ▁Ro ads ▁Sch eme ▁in ▁the ▁ 1 9 6 0 s ▁resulted ▁in ▁a ▁notice ably ▁higher ▁quality ▁road ▁in