What is the correct treatment for a signal aspect with a dark lower light?

• A. Red
• B. Green
• C. Yellow
• D. Not applicable

Answer: (A)

When a signal has two lamps and the lower lamp is dark, there is no clearance being shown by that lower position. In Canadian practice, a dark lower light on a two-lamp signal is treated as a stop indication, regardless of what the upper lamp might be showing. That’s why red is the correct treatment here: the absence of a valid lower-lamp indication means you must not proceed and should stop, until a proper lower-lamp color is illuminated or another authorized indication is given. Green or yellow would only apply if the lower lamp were lit in those colors as part of a valid proceed or caution signal, which is not the case when the lower light is dark. Not applicable isn’t appropriate because a defined rule exists for this situation, and it requires stopping.