When winter hits, the heavy recovery operators of Southern Ontario fight to clear wrecks and keep drivers moving on the busiest stretch of highway in the world. Up to 400,000 vehicles travel Ontario's 400-series highways every day. The section of the 401 through Toronto is the busiest stretch of highway in the world. Highway 402 near Sarnia is an important link to the US Midwest, plagued by blinding lake effect snow squalls. These routes are lifelines for the nation's industrial heartland and for thousands upon thousands of commuters. When disaster strikes on these roads, the pressure is on to get them cleared and reopened. Police and the Ministry of Transport depend on Southern Ontario's heavy recovery operators. To keep closures to a minimum, crews often work just inches from open lanes and speeding traffic.