The Prepare to Stop sign indicates to drivers in advance of a traffic control signal that there is a high probability of having to stop for a red signal indication. The primary function of the Prepare to Stop sign is to reduce dilemma zone incidents.

As a general rule, the Prepare to Stop sign should only be used where traffic engineering studies, considering such aspects as traffic speeds, traffic volumes, visibility and collision experience, indicate that this sign is warranted.

Without restricting the intended usage, the Prepare to Stop sign may be considered at locations where one or more of the following conditions exists:

1. Signals installed on roads with a speed limit of 70 km/h or greater
2. Signals at which sight restrictions are present
3. Signals at the bottom of a downgrade of considerable length