While driving to work the other morning, I spotted a very large and very odd-looking plow, eating snow up with a big conveyor belt. What was it?—Judy McNab, North York

As you might expect, Toronto’s snow-removal fleet consists mostly of utilitarian road plows and salters. As of this winter, the city has 673 of the former and 201 of the latter, enough artillery to take on the nastiest of winter storms. But we’ve also got three 17-metre-long trucks that ingeniously melt snow right on the street. The conveyor system in the front (called an auger) picks up the snow and dumps it into a “melting pit”—a bubbling Jacuzzi that liquefies the white stuff faster than ice cream in a blast furnace. As the snow melts, it drains off into adjacent sewers. Alas, though they can melt up to 136 tonnes of snow in an hour, the beasts crawl along at a glacial speed, tying up traffic for blocks. They also have to be cleaned out every 12 to 16 hours because they get clogged with street grit. But the snow-melting machines have a major upside: they eliminate the need for road salt, making them an environmentally friendly way of clearing the streets.

• Categories: Environment