Winter Road Terminology

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Condition	Definition
Closed	Highway is impassable (or has been closed for operational reasons or weather).
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.
Heavy Snow	More than 8 cm of loose snow covers the driving surface. Traffic encounters problems when meeting or passing.
Ice Covered	The entire driving surface is covered with ice.
Icy or slippery sections	A minor situation identified due to intermittent rain, frost, sticking snow or ice patches (includes light pavement frost).
Loose Snow	Less than 8 cm of loose snow covers the driving surface that may cause some driving difficulties.
Pavement Frost	Build-up of frost that reduces braking power of vehicles.
Seasonal Driving	No specific problems however there could be the occasional condition.
Slush	A build up 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.
Snow Drifts	Small snow dunes exist on the driving surface at intermittent intervals.
Snow Packed	This condition exists mainly on gravel roads where the entire driving surface is covered with packed snow.
Swirling Snow	A condition created by traffic in loose snow that reduces visibility.
Travel Not Recommended	This means that visibility is less than 250 metres (poor); and/or the surface is icy; and/or the highway is doubtful; and/or the highway may be blocked.
Visibility Good	You can see more than 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 Reduced	You can see less than 250 to 500 metres.
Visibility Zero	You can see less than 100 metres. Under this condition, highway maintenance equipment may be removed.
Wet/freezing	Highway is wet, subject to freezing as temperatures drop.
Winter Conditions Exist	If conditions other than seasonal driving are reported, it automatically shows winter conditions exist (yellow line on the map). This may include icy, slippery sections or swirling snow.