UPDATE: Interstate 75 has been re-opened after a wintery mix of sleet and freezing rain made the morning commute a challenge Monday.

A 37-vehicle pile-up closed the roadway for several hours Monday morning in Catoosa County, near Battlefield Parkway, has closed the northbound lanes.

Fifteen people were injured in the pile-up and were transported to local hospitals for examination and treatment.

Nearly 100 gallons of diesel fuel were spilled and is bring cleaned up.

READ MORE | Channel 3 school closings & delays

Traffic was-re-routed to US-41, causing a ripple effect of traffic on nearby surface roads.

GDOT projects to have the road re-opened by 12:30pm.

Bear in mind that conditions can change quickly, allow extra time and space between cars and drive with extra caution.

GDOT and TDOT crews hit the roads Sunday, spreading brine on major roads to prevent freezing.

Chattanooga Public Works has been out since 3:00 a.m. spreading sand on the roadways. 

In Alabama, icy roads are causing travel problems, and authorities are advising against travel on some mountain roads in the state's northeast corner.

The DeKalb County Emergency Management Agency reports on its Facebook page that roads throughout the mountainous county are impassable because of slippery conditions.

The Alabama Law Enforcement Agency says freezing rain and icing are being reported in DeKalb and Jackson counties.

About a dozen school systems in northeastern Alabama have delayed the start of school because of the threat of travel problems, but the threat doesn't extend into the state's most populous metro area around Birmingham.

Forecasters say any problem areas should melt by lunchtime as temperatures rise.

Several school systems have delayed or closed Monday morning. 

Here's our list of possible trouble spots:

HAMILTON

  • Roberts Mill Road - closed due to icy conditions
  • W Road closed due to icy conditions
  • US-27 - patchy ice
  • Several crashes on Bonny Oaks
  • 9600 block of Mahan Gap Road closed to traffic

BRADLEY

  • 6:30 a.m Roads are wet and no icy spots have been reported. 

BLEDSOE

  • 6:30 a.m. There is ice in the higher elevations and it's just beginning to rain in the valley. 

CATOOSA

  • Northbound Interstate 75 near mm 345, Battlefield Parkway, closed by crash; Catoosa County dispatchers tell Channel 3 there are several crashes on the interstate
  • Crash at Aikens Rd and Battlefield Pkwy
  • Crash in the 1800 block Red Belt  
  • Hwy 41 between Haletown and Lookout Valley is covered in ice road closed until further notice.
  • Graysville Rd is icy

DADE

  • 6:45 a.m. Secondary roads slick, crews are out working them.

GRUNDY 

  • 6:45 a.m. Interstate 24 and other roads icy.  Crews are out salting roadways.

MARION

  • 6:45 a.m. Hwy 27 over Suck Creek Mountain solid sheet of ice
  • 6:45 a.m. Hwy 108 over Whitwell Mountain solid sheet of ice
  • 6:45 a.m. Hwy 41 into Haletown solid sheet of ice
  • 6:45 a.m. Interstate 24 over Monteagle icy conditions

MEIGS

  • 6:50 a.m.  Secondary roads icy conditions

RHEA 

  • 7:00 a.m. Hwy 27 passable. 
  • 7:00 a.m. Patches of black ice on Dayton Mountain

SEQUATCHIE

  • 7:00 a.m. Hwy 127 on Signal Mountain in Sequatchie County closed due to ice.
  • SR 8 North in Sequatchie closed between Clear Brooks Drive and Sequatchie Van Buren County Line 

WALKER

  • 7:00 a.m Secondary roads slick 

WHITFIELD

  • 7:00 a.m. Icy conditions 
  • Varnell and Cohutta roads are icy. No road closures 
  • I-75 NB exit 341 is closed