Winter Road Terminology

You can also download the Highway Hotline Terminology Fact Sheet in PDF format.

Visibility Conditions
Conditions	Definition
Visibility Good	You can see more than 500 metres.
Visibility Reduced	You can see between 250 to 500 metres.
Visibility Poor	You can see less than 250 metres. Under this condition, Highway maintenance equipment will not begin work on the road until visibility improves. Equipment already on the road may be removed if visibility continues to deteriorate.
Visibility Zero	You can see less than 100 metres. Under this condition, Highway maintenance equipment may be removed.

Primary Conditions
Conditions	Definition
Bare (Dry/Wet)	All wheels of a passenger vehicle are on a bare surface, and some patches of snow and ice may be present. – Bare and Dry: Most of the road surface is dry. – Bare and Wet: Most of the road surface is wet.
Partly Covered	Two wheels of a passenger vehicle are on a snow or ice-covered surface.
Covered	All wheels of a passenger vehicle are on snow or ice.
Travel Not Recommended	This means that visibility is less than 250 metres (Poor); and/or highway could become impassable due to road surface conditions (ice, snow, snow drifts, etc.) or extreme weather events.
Closed	Highway is impassable (or has been closed for operational reasons or weather).
Report Not Available	Unable to report


Secondary Conditions
Conditions	Definition
Pavement Frost	Buildup of frost that reduces braking power of vehicles.
Slush	A buildup of slush on the driving surface as a result of moderate or heavy snow fall when pavement temperatures are at or near the freezing point creating driving conditions that may cause an unsuspecting driver to lose control of a vehicle.
Ice	The driving surface is partly covered or covered with ice.
Loose Snow	Less than 8 cm of loose snow partly covers or covers the driving surface that may cause some driving difficulties.
Heavy Snow	More than 8 cm of loose snow partly covers or covers the driving surface. Traffic encounters problems when meeting or passing.
Snow Packed	The driving surface is partly covered or covered with packed snow.
Snow Drifts	Snow drifts exist on the driving surface at intermittent intervals.
Swirling Snow	A condition created by traffic in loose snow that reduces visibility.
Drifting Snow	Ground drifting caused by winds which may affect surface conditions on the highway, such as sticking snow or may reduce visibility.
Fog	Reported only when visibility is reduced.