Sentence:  The trip took longer than usual–following the snow plow <WSD>conga line</WSD>, and dodging spinning Expeditions and Jimmys as they pirouetted off the road. 
Meaning of the word marked with <WSD> tags:  A moving formation of snowplows and/or similar equipment, arranged in a diagonal line across a multilane highway, airport runway, or other roadway, such that the snow from the first vehicle is passed to the second, and then from the second to third, and so on, thereby clearing much or all of the route's width in a single pass.