or ▁and ▁express ▁lan es , ▁giving ▁the ▁highway ▁a ▁wide ▁span ▁and ▁four ▁carriage ways . ▁To ▁avoid ▁confusion ▁between ▁carriage ways , ▁blue ▁signs ▁are ▁used ▁for ▁the ▁collect or ▁lan es ▁and ▁green ▁signs ▁for ▁the ▁express ▁lan es . ▁Un like ▁the ▁collect or ▁lan es , ▁which ▁provide ▁access ▁to ▁every ▁inter change , ▁the ▁express ▁lan es ▁only ▁provide ▁direct ▁access ▁to ▁a ▁select ▁few ▁inter changes . ▁Access ▁between ▁the ▁two ▁is ▁provided ▁by ▁trans fers , ▁which ▁are ▁strateg ically ▁placed ▁to ▁prevent ▁dis ru ptions ▁caused ▁by ▁closely ▁spac ed ▁inter changes . ▁The ▁overall ▁purpose ▁of ▁the ▁collect or - express ▁system ▁is ▁to ▁maxim ize ▁traffic ▁flow ▁for ▁both ▁local ▁and ▁long - distance ▁traffic . ▁In ▁addition , ▁Highway   4 0 1 ▁was ▁equ ipped ▁with ▁a ▁traffic ▁camera ▁system ▁called ▁CO MP ASS ▁in ▁early ▁ 1 9 9 1 . ▁Using ▁closed - circ uit ▁television ▁cam eras , ▁vehicle ▁detection ▁loops ▁and ▁LED ▁change able - message ▁signs , ▁CO MP ASS ▁enables ▁the ▁M TO ▁Tra ffic ▁Oper ations ▁Centre ▁to ▁obtain ▁a ▁real - time ▁assess ment ▁of ▁traffic ▁conditions ▁and ▁alert ▁drivers ▁of ▁coll isions , ▁con g estion ▁and ▁construction . ▁The ▁system ▁st ret ches ▁from ▁the ▁Highway   4 0 3   / ▁ 4 1 0 ▁inter change ▁in ▁Mississ aug a ▁to ▁Har wood ▁Avenue ▁in ▁Ajax . ▁ ▁Two ▁sets ▁of ▁collect or - express ▁systems ▁exist ▁in