The disruption caused by the heavy snowfall across England looks set to continue overnight.
Up to 10cm (4in) of snow fell in some areas
Forecasters have said the melted snow could turn to ice by the morning, leading to hazardous conditions.
Hundreds of schools across the country have been closed and all 435 schools in Birmingham will remain closed on Friday.
Gritters have been out and drivers are being warned not to travel unless their journey is essential.
The blanket of snow on Thursday stretched from the south of England across the Midlands and reached up to Lancashire and north of the Humber.
Some hilly areas were likely to receive up to 6in (15cm) of snow during the day, the BBC Weather Centre said.
And it forecast that overnight temperatures would fall to as low as -3C (26F), with a chance of ice forming.
A Highways Agency spokesman said that generally there had been the usual number of incidents on the roads as drivers made their way to work.
In a statement it said: "The Highways Agency has been working through the night to grit motorways and major trunk roads and is continuing to work to keep those roads open."
The agency has 400 salt-spreading vehicles on stand-by.
A lorry jack-knifed on the A3 at Hindhead, Surrey, on Thursday morning causing a small stretch of the A3 to close southbound.
Essex Police said they had been called to more than 150 incidents across the county, and Kent Police warned that rural routes and side roads had been affected by snow.
A spokesman for Wiltshire Police said 19 snow-related road accidents were reported between 0400 GMT and 0900 GMT, but none were serious.
The A36 near Salisbury was closed for a short time while a trapped driver was removed from his vehicle.
Thousands of airline passengers had their flights delayed or cancelled on Thursday.
Passengers were advised to check with their airlines for advice on what to do.
All flights from Luton Airport were suspended in the morning, but began again after 1230 GMT.
A spokesman said: "The weather is improving and things are starting to move now."
The runway at Stansted Airport was closed just after 0600 GMT as more than half a million square metres of snow needed to be cleared.
It reopened at 1100 GMT and ground teams are now working to clear the backlog of flights.
Gatwick Airport's runway was shut briefly and about 20 flights were cancelled.
Overnight temperatures could fall to as low as -3C (26F)
On the railways, Network Rail said all routes were open, but services were running with delays.
Virgin Trains operated an amended timetable on services into and out of London Euston.
It said it would run hourly services to each of its major destinations, with journey times likely to be extended.
Train services run by South West Trains and Southern into London and First Great Western to Gatwick Airport were among those cancelled or disrupted.
London's Tube services were also affected.