Several large pieces of armour stone spilled onto Highway 402 on Wednesday morning after a transport drove into the centre median.
OPP say the westbound highway was down to one lane between Forest Road and Oil Heritage Road as crews worked on the cleanup.
Motorists were being urged to avoid that area for the time being.
Transport drives into centre median and looses load of boulders on Highway 402 this morning. #hwy402 #loadsecurity #MTOofficer #MTOofficers #roadsafety @CVSA @ONtruckOfficers @TeoOntario @IAm4RoadSafety @Media371 @ONtransport @BlackburnSarnia pic.twitter.com/GgRsBfUUYg
— OPSEU 139 - MTO (@opseu139) March 11, 2020