The trailers everyone is talking about are called tow plows. Towed behind a conventional plow truck, hydraulic controls turn the wheels, drop the blade and activate the augur chain. These behemoths can clear two and a half lanes in one shot. That I know of Mass., Penn., Missouri, and Iowa uses these. Granted, they do a good job, but in heavy traffic areas they are not effective. A echelon of plows will do provide the same results. If you want my opinion, these tow plows are the DOT's answer to fire service quints, do more with less.
For those interested, you tube has a bunch of videos showing the tow polws in action'
For those interested, you tube has a bunch of videos showing the tow polws in action'