The speed limit on Interstate 79 has been reduced to 45 miles per hour and all commercial vehicles must travel in the right lane between Exit 76 to the Route 19 exit in Cranberry Township, according to the state Department of Transportation.

PennDOT released the restrictions at about 9:25 a.m. as heavy snow continued to fall on Butler County.

Motorists are asked to use caution when travelling in winter weather, reduce speeds and be aware of changing weather conditions.

PennDOT officials say on packed snow, vehicle speed should be reduced by half, and on ice, vehicles should travel at a crawl.

More space should be allowed between vehicles proceeding down a road, street or highway in bad weather.

Brakes should be applied gently and operators should ease off if they begin to slide. Brakes can be reapplied after control of the vehicle is regained.

Cruise control should be avoided on slick roads, PennDOT said.