Motorists and public transit users are slogging through a messy and slow evening commute after a low-pressure system walloped the Greater Toronto Area and parts of southern Ontario with heavy snow and strong winds Wednesday.

Police have been called to dozens of collisions and they are urging motorists to slow down and, if possible, stay off the roads. Highways in the GTA were averaging a crash every minute at one point Wednesday morning.

“We are seeing zero visibility in some places (and) icy road conditions, specifically on the ramps, and it is just one crash after another coming in right now,” Ontario Provincial Police spokesman Sgt. Dave Woodford told CP24 earlier Wednesday. “If you don’t have to be out there, don’t be.”

OPP said the biggest problems are motorists who are driving too fast and aggressive driving.

East of Toronto, motorists were stranded in Highway 401's westbound lanes, west of Napanee, after a multi-vehicle pileup involving about 150 cars and trucks. The lineup snaked along the highway for several kilometres and the delay lasted hours.

Another multi-vehicle crash on Highway 401 in Trenton forced more road closures, trapping commuters in stalled traffic for more than four hours.

In Toronto, Mayor Rob Ford told people to top up their vehicles' gas tanks and to "prepare for the worst" if they venture onto the roads.

Snowfall warning ended

A snowfall warning issued for the City of Toronto and much of the GTA ended shortly after 4 p.m. after the region was slammed with between 15 and 20 cm of snow.

“The heaviest accumulations in the area were localized in Toronto and areas to the northeast,” CP24 meteorologist Chris Potter said late Wednesday afternoon.

An extreme cold weather alert issued Wednesday morning by the City of Toronto remains in effect to increase services for the homeless as the temperature is expected to drop overnight.

“Overnight lows in the GTA will be in the minus mid-teens, and it will feel at times like the minus 20s,” Potter added.

City of Toronto crews began salting and plowing roads and sidewalks Wednesday morning, starting with primary routes.

Hector Moreno, the city’s manager of road operations, said crews will begin clearing residential streets in the afternoon and the job will likely take up to 18 hours to complete.

The city is asking property owners to shovel their sidewalks and not to push snow onto the street.

Because roads are slippery and visibility is limited in some areas, police are reminding motorists to slow down, leave extra room between vehicles in case of a sudden stop, and depart earlier than normal because it will take longer to get to their destination.

TTC shuts down SRT

The weather is affecting public transit users, as well.

To prepare for the afternoon rush, the TTC shut down the aging Scarborough RT line to remove ice and snow from the tracks.

While the TTC had hoped to have service up by 3 p.m., TTC spokesperson Brad Ross announced Wednesday night that service would not resume until Thursday morning.

While the SRT is closed, 18 shuttle buses will be running between Kennedy and McCowan stations, Ross said.

Workers have applied deicer along the Bloor-Danforth subway line and crews are keeping an eye on subway and streetcar track switches and streetcar wires to avoid delays.

Earlier, the TTC told its streetcar passengers to expect delays, and GO Transit was reporting delays of about 45 minutes on some routes.

School buses were cancelled by some school boards in the GTA. Click here for a full list.

Airlines issue travel alerts

Travel advisories issued by airlines are warning of delays or cancellations in Toronto and other Canadian and American cities affected by the storm.

People should check their flight status before heading to the airport.

At Pearson International Airport, about 100 pieces of snow removal equipment, including plows and deicers, were in use at the height of the storm, the Greater Toronto Airports Authority said.

With files from CP24 reporters Cam Woolley and Nathan Downer.

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