Mandatory road signs can be used to allocate certain areas to specific vehicles - the Vienna Convention explicitly mentions footpaths, cyclepaths and bridleways, but tramways, bus lanes, taxi lanes, HOV lanes and snow mobile tracks can also be designated with mandatory signs. When a specific area of roadway is designated with a mandatory sign specifying a vehicle type, all traffic of this type must use this area if possible. These signs can be combined by putting one pictogram above the other. If the pictograms are side-by-side however, with the sign divided by a white vertical line, each type of vehicle must stay within the lane indicated by the sign. A red line through a mandatory sign indicates not that a vehicle of a specific type is prohibited from entering the designated area, but that the area is now deregulated and any vehicle may use it.

The mandatory sign group is not used in the United States and Canada, who are not signatories to the Vienna Convention; both countries consider them kinds of regulatory signs. Some Canadian provinces differentiate mandatory signs from prohibitive ones by enclosing the symbols in a green rather than red border, although this can indicate either a mandatory or a warning sign, while in the U.S., the only difference between a prohibitory sign and a mandatory one is that a mandatory sign includes the word "only" at the bottom of the plate instead of crossing out the pictogram.

Traffic metal signage walking mandatory sign