Classification of Warning Signs

Warning signs are classified into the following groups according to their particular function:

WA: Physical conditions, WB: Traffic regulations ahead, WC: Intermittent or moving hazards

A determination of the appropriate sign to be used should be made in accordance with the criteria outlined in the Uniform Traffic Control Manual of Canada. When there is doubt about which sign to use, the one requiring the minimum restrictions should be installed. The specifications for warning signs outlined here will adequately provide for most conditions which are encountered. However, if additional warning signs not contained in the Uniform Traffic Control Manual are needed, they should conform to the standard shape and color for warning signs and the message should be conveyed with a symbol. If a word message is necessary, it should be brief and simple.

Design of Warning Signs

Warning signs are placed to provide advance warning of a condition primarily for drivers who may not be familiar with the road. Therefore, it is very important that thought and care be given to their location and installation. Warning signs are normally installed between a minimum of 50 m and a maximum of 150 m in advance of the corresponding condition. However, in some locations, the physical situation will require different distances. In those cases, trial runs should be made by day and by night to determine the most effective location and installation characteristics for each situation. In cities, where speeds are relatively low, warning signs usually should be placed closer to the location of the condition than on rural highways.

Bicycle Path Warning Signs

Warning signs on bicycle paths advise cyclists of changes in physical conditions, traffic regulations, movinghazards or temporary conditions. On separate rights of way, appropriate warning signs may be installed as described in Warning Signs. Reduced-size signs must conform with the provisions of all Warning Signs. The minimum size for any use is 45cm x 45cm.

Road Alignment

Unexpected changes in road alignment may require the use of warning signs to advise drivers of such conditions. Abrupt turns or curves, or the termination of road sections, may involve hazardous driving situations unless drivers are advised in advance of these conditions.

The maximum practical speed is an indication of the maximum speed that reasonably could be maintained over a section of road in advance of the curve under consideration, having regard to pavement and shoulder widths, horizontal and vertical alignment, sight distance and other controlling factors. This does not necessarily coincide with the design of the road.