▁there ▁has ▁been ▁an ▁environmental ▁assess ment ▁on ▁w iden ing ▁highway ▁ 4 0 1 , ▁extending ▁the ▁collect or - express ▁system ▁east ▁towards ▁S alem ▁Road ▁in ▁Ajax ▁and ▁to ▁ 1 0 ▁lan es ▁from ▁Bro ck ▁Street ▁in ▁Whit by , ▁to ▁Court ice ▁Road ▁in ▁the ▁Municip ality ▁of ▁Cl aring ton . ▁The ▁assess ment ▁was ▁completed ▁in ▁March ▁ 2 0 1 5 . ▁ ▁All ▁the ▁original ▁over pass es ▁d ating ▁back ▁in ▁the ▁ 1 9 4 0 s ▁and ▁ 1 9 5 0 s ▁built ▁between ▁Whit by ▁and ▁O sh awa ▁will ▁gradually ▁be ▁replaced ▁with ▁new ▁over pass es ▁as ▁part ▁of ▁modern ▁highway ▁safety ▁standards ▁and ▁to ▁allow ▁highway ▁w iden ing ▁som etime ▁in ▁the ▁future . ▁ ▁Eastern ▁Ontario ▁ ▁East ▁of ▁Dur ham , ▁the ▁M TO ▁is ▁planning ▁to ▁w iden ▁parts ▁of ▁Highway   4 0 1 ▁to ▁six ▁lan es . ▁Pre lim inary ▁work ▁includes ▁the ▁w iden ing ▁of ▁the ▁bridge ▁over ▁the ▁Tr ent ▁River ▁in ▁Tr ent on , ▁as ▁well ▁as ▁the ▁real ignment ▁of ▁some ▁roads ▁alongside ▁the ▁highway . ▁By ▁ 2 0 1 2 , ▁the ▁highway ▁was ▁w iden ed ▁to ▁six ▁lan es ▁for ▁ ▁through ▁King ston ▁between ▁ex its ▁ 6 1 1 ▁and ▁ 6 1 9 . ▁Const ruction ▁began ▁in ▁ 2 0 1 4 ▁to ▁expand ▁the ▁highway ▁to ▁six ▁lan es ▁approximately ▁ ▁east