With the heavy snow that pummeled the mid-Atlantic states last week, there were a number of news stories about tractor trailers which were involved in pile-ups in the bad weather. One report came from Maryland where a tractor trailer hit one vehicle that slowed for another car ahead of him and was rear-ended by a tractor trailer. The three-vehicle pile-up turned into a nine-car pile up as following vehicles, including another tractor-trailer, slammed into the pile-up. Five people had to be taken to the hospital.One of the things that stood out to me about this story was the description of the poor weather conditions, including snowy and icy roads and blowing snow. The other thing that stood out to me was that there were two tractor trailers involved in the accident.The reason that this stood out to me is that neither of the tractor trailers should have been on the road. 49 CFR Part 392.14 requires truck drivers to slow their vehicles and to exercise extreme caution when hazardous conditions such as snow, ice, fog, or smoke are present and if conditions are sufficiently dangerous, to cease operations and pull to the side of the road or exit the road. When there are slick, icy, snow-covered roads with blowing snow that further restricts visibility, the trucks should be getting off the road. Why? Because poor road conditions make it harder to stop and the enormous weight of the tractor-trailer make it likely that an accident will produce serious injuries.