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News Release

January 14 , 2005

Mn/DOT Warns of Black Ice


Mankato, Minn. - The Minnesota Departments of Transportation is warning drivers of black ice.

"Black ice can be one of the most dangerous conditions on winter roads," said District Engineer Jim Swanson. "It is almost invisible and can catch drivers off guard," he added. Black ice is clear and appears black because the dark asphalt surface underneath shows through. It can form on heavily congested highways from auto emissions, but other roads are susceptible including those in shaded areas, near lakes and rivers, in tunnels and on overpasses.

Drivers can increase safety by observing the following tips:

  • Be aware that black ice is almost invisible.
  • Be especially careful on bridges, overpasses and tunnels and in early morning when the air temperature is rising faster than the pavement temperature.
  • Never brake while driving on ice. Applying pressure to your brakes while on ice will cause a vehicle to skid. Brake only during your approach.
  • Keep your distance. The distance needed to stop on ice is twice as long as under normal driving circumstances. Keep at least a three-car distance from the vehicle directly in front of you.

Black ice forms when the air temperature is warmer than pavement, which causes moisture to rapidly freeze and create a thin, transparent layer of ice on the roadway.

It can be neutralized with salting and sanding. However, drivers should be aware that salt loses its effectiveness at about 15 degrees and colder.

Traveler information, including incident reports, is available by calling 511 or logging on to Know the Road. Dialup or log on.

Work Zones. Pay Attention or Pay the Price.


Rebecca L. Arndt
Public Affairs Coordinator
Mn/DOT District 7


District 7
Mankato/Windom Office
501 S. Victory Dr.
Mankato, MN 56001

Tel: 800-657-3747
Fax: 507-389-6281