18 and 24-hour service roadways

County highway departments maintain the state's highways for either 18-hours or 24-hours per day during a winter storm event as conditions warrant. The following is an explanation of the 18/24 hour guideline:

View interactive map​ - Updated October 2022

General guideline

State highway maintenance during the winter months has two distinct highway classifications: "High Volume" and "All Other." These classifications are described below.


The high volume highway classification would typically include highways with four or more lanes for through traffic and selected two-lane highways. When determining the need for providing high volume coverage on two-lane highways, the following should be considered:

  • Functional classification
  • High traffic volumes
  • Special service factors
  • Planned conversion from a two-lane to a multi-lane facility

The "all other" highway classification would include all those highways not identified as high volume.

High volume highway expectations

When conditions warrant, 24-hour coverage should be provided during a winter storm. Depending on the severity and duration of the storm, maintaining a full complement of operators may not be practical. However, some minimal coverage should be provided (perhaps by reducing or staggering the workforce).

Definition of "24-hour coverage:" 24-hour coverage means that the county has a presence on the highway for 24 hours per day during a winter storm event unless passable roadway conditions have been achieved. This would only happen during winter storm events of long duration and when conditions warrant. When this does occur it may mean further reducing the coverage on routes in the "all other" classification to assure available manpower, or extending the winter operation section lengths on the high volume routes. However, continuous coverage does not mean that the county runs three shifts or that there are patrol trucks on the highway 24 hours per day throughout the winter irrespective of weather conditions.

"All other" highway expectations

When conditions warrant, coverage should be provided up to 18 hours per day during the storm. The gap in coverage is necessary to provide for operator recovery time. The operator recovery time should typically be between the hours of 10 p.m. and 4 a.m., but will vary with specific storm conditions.

Some minimal ability to respond to emergencies should be provided during the hours that full coverage is not provided.


The above highway classifications and coverage times are intended as a guide in winter maintenance operations and changes may be deemed appropriate based on local conditions. Exceptions to these guidelines may include:

Reducing coverage due to extreme conditions which would include:

  • Limited visibility for operators
  • Length and severity of the storm
  • Continuing service beyond suggested hours to prevent snow compaction or other hazardous conditions
  • Allowing breaks between shifts during off ADT peak hours to reduce operational costs and operator fatigue

Service uniformity

Customers place a high value on our ability to minimize unexpected changes in pavement condition. Therefore, a primary objective in supplying winter snow and ice control is to achieve consistent service on similar facilities. Please note that even when exceptions as listed above are made, we should strive for uniformity of service. This means that winter maintenance sections should end at logical locations where a motorist might anticipate a change in service. These might include:

  • High volume intersections or interchanges where traffic volumes significantly change
  • Leaving or entering municipalities
  • Dramatic or well defined changes in topography

​Providing continuity of service across jurisdictional boundaries will require close coordination between counties and WisDOT regions.