Highway 401 westbound finally reopened early Wednesday evening after being closed for much of the day west of Ingersoll following three multi-vehicle collisions.
OPP had closed a 10 kilometre stretch of the road as of mid-day at Culloden Road after dozens of vehicles became involved in a tangled mess.
A bus with over a dozen passengers on board tried to avoid the collisions ahead, but ended up slamming into the back of a transport truck.
Shoaib Ali was on board the bus and says "A few people started screaming, I was just praying...No one was hurt besides the bus driver, but thank God for the bus driver because he avoided a tragedy."
The driver had to be freed from the wreckage by emergency crews, but appeared to have escaped with no serious injuries.
The full extent of injuries to those involved in the pile-up and the total number of vehicles damaged remains unclear.
OPP Const. Laurie Houghton says these types of situations "Pulls out all our resources, we've got fire, EMS, OPP from multiple jurisdictions trying to assist today.
There also were numerous crashes and vehicles in the ditch across the region from Windsor through the London area and continuing east through southern Ontario, prompting police to remind motorists to slow down and adjust to the conditions.
Police have message for truckers - slow down
Wednesday morning, motorists in Lambton County experienced delays as the westbound Highway 402 was reduced to one lane after a transport truck partially blocked the passing lane between Airport Road and Modeland Road.
In Middlesex, OPP responded to three jackknifed tractor trailers in less than 30 minutes along Highway 401 on Wednesday morning, prompting a statement asking transport truck drivers to slow down.
OPP Sgt. Dave Rektor says "We realize just-in-time transit has a lot to do with timelines and so-forth but that's null and void on a day like today. There's nothing just-in-time in a winter whiteout. Everything needs to slow down to a crawl and we need people to drive responsibly."
Police say having a higher vantage point than other vehicles does not make the roads less slippery and trucks can also create additional visibility problems with the snow and debris that blows around them.