Slick, snow-covered roads remain throughout the region after more snow fell since Wednesday.
More heavy lake-effect snow and below zero temperatures took ahold of the area Thursday night.
Indiana State Police said the expressways were snow-covered, slick and hazardous. Troopers responded to scattered slide-offs all day Thursday, police said.
Indiana State Police for the Toll Road said the snow Thursday came in waves. When the snowfall rate tapered, however, strong winds were causing the road to ice over, causing slide-offs and spin-outs.
No serious injuries were reported in any of the crashes, police said.
A spokesman for the Indiana Department of Transportation said more than 170 snow plow drivers hit the roads in northern Indiana when the snow began to fall Wednesday night.
Matt Deitchley, INDOT spokesman, said plows treat lanes on state highways every two to three hours as drivers cycle through their routes.
Deitchley urged people to avoid unnecessary travel in the region.
Lake County Highway Superintendent Marcus Malczewski said he had a full complement of 35 trucks out plowing Thursday.
"The roads are snow packed and people need to slow down. But we are keeping up with it because snow is fluffy and we have no huge wind yet. If that wind kicks up, that can close a lot of roads in the south," Malczewski said.
The weather prompted Purdue University Calumet to close the campus in Hammond at noon. University officials said the final payment deadline for spring tuition was extended to 4 p.m. Friday.
Prairie State College in Chicago Heights also closed campus early at 1 p.m. due to the weather.
The holiday week is expected to keep traffic volume down, with many people off work and children out of school.
Eric Lenning, meteorologist with the National Weather Service, said most of the region had about 3 inches of accumulation from the New Year's Day snowfall.
A lake-effect snow warning was in effect for the region until midnight Thursday, with up to 8 inches of snow possible. Lenning said the lake-effect snow began falling around 6 a.m.
The heavy snow and strong winds gusting up to 30 mph could cause blowing and drifting snow and result in zero visibility.
A lake-effect snow warning is in effect in Porter County through 4 a.m. Friday. An additional 2 to 5 inches of snow are expected in Porter County.
As the snow begins to taper off, temperatures are going to plummet to 3 below zero with wind chills as low as 17 below zero by today.