CHICAGO (CBS) — It’s been a couple years since Chicago has seen a snowstorm as big as the one that began blanketing the city Thursday night, but city officials wanted to assure residents they haven’t forgotten how to keep the city moving.

At a briefing at the city’s 911 Center, Mayor Rahm Emanuel weighed in on how he thinks the city is responding to the biggest snowstorm of the season.

“The last two winters haven’t been heavy from a weather side. This is more reflective of what we kind of think about when we have in our mind’s eye what does a Chicago winter look like. The good news is we’re tried and tested here,” he said. “Everybody here didn’t just show up today to figure out how to respond to this. We are tried and tested as a system. We’re up to it.”

The mayor said what’s different about this snow event is it’s coming in waves, rather than one big snow dump and it’s over.

“This is coming, stopping, coming, stopping, coming; and everybody’s going to be working all the way through to make sure that people are safe,” he said.

Snow plows have been out since Thursday evening, clearing snow and spreading salt.

More than 300 snow plows have been working around the clock to clear and salt more than 9,400 lane miles of streets across the city.

Tens of thousands of tons of salt were being used from the city’s supply of more than 400,000 tons for this winter.

The city has largely focused on plowing main streets and Lake Shore Drive, only occasionally hitting some side streets. Crews will only switch their focus to side streets after the snow stops.

Contractors also have been busy clearing parking lots and sidewalks for local businesses, so customers can easily get in and out. One contractor described the storm as money falling from the sky.

Despite the best efforts of plow operators, driving remained treacherous. So, if you don’t have to drive anywhere on Friday, don’t.

There have been dozens of crashes and spin-outs, but the only confirmed fatality has been a tow truck driver who was killed after pulling over to change a tire on Interstate 294. Illinois State Police said the driver was killed when the jack slipped, and the truck fell on top of him.

Meantime, Chicago Public Schools were closed on Friday. CPS hadn’t closed schools for snow since the Groundhog Day blizzard of 2011 — which buried the city in 21.2 inches of snow in one day, though it has closed several times since then for extreme cold.

“We’re going to make it up in the school year. I don’t regret the decision,” he said.

Although schools were closed on Friday, the city’s 80 libraries remained open.

The storm also has forced airlines to cancel hundreds of flights at O’Hare and Midway airports. As of 11 a.m., more than 810 flights had been cancelled on Friday at O’Hare, and more than 310 had been cancelled at Midway.