▁occup ies ▁only ▁a ▁portion ▁of ▁this ▁all ot ment . ▁It ▁is ▁one ▁of ▁the ▁world ' s ▁bus iest ▁high ways ; ▁a ▁ 2 0 1 6 ▁analysis ▁stated ▁the ▁annual ▁average ▁daily ▁traffic ▁( A AD T ) ▁count ▁between ▁West on ▁Road ▁and ▁Highway   4 0 0 ▁in ▁Toronto ▁was ▁nearly ▁ 4 2 0 , 0 0 0 , ▁while ▁a ▁second ▁study ▁estimates ▁that ▁over ▁ 5 0 0 , 0 0 0   ve h icles ▁travel ▁that ▁section ▁on ▁some ▁days . ▁This ▁makes ▁it ▁North ▁America ' s ▁bus iest ▁road way , ▁sur pass ing ▁the ▁Santa ▁Mon ica ▁Fre ew ay ▁in ▁Los ▁Angeles ▁and ▁I - 7 5 ▁in ▁Atlanta . ▁The ▁just - in - time ▁auto ▁parts ▁delivery ▁systems ▁of ▁the ▁highly ▁integrated ▁autom ot ive ▁industry ▁of ▁Michigan ▁and ▁Ontario ▁have ▁contributed ▁to ▁the ▁highway ' s ▁status ▁as ▁the ▁world ' s ▁bus iest ▁tr uck ▁route , ▁carrying ▁ 6 0   percent ▁of ▁veh icular ▁trade ▁between ▁Canada ▁and ▁the ▁US . ▁ ▁Highway   4 0 1 ▁also ▁features ▁North ▁America ' s ▁bus iest ▁multi - structure ▁bridge ▁at ▁Hog g ' s ▁H ollow ▁in ▁Toronto . ▁The ▁four ▁brid ges , ▁two ▁for ▁each ▁direction ▁with ▁the ▁collect or ▁and ▁express ▁lan es , ▁carried ▁an ▁average ▁of ▁ 3 7 3 , 7 0 0   ve h icles ▁daily ▁in ▁ 2 0 0 6 . ▁The