What does a diamond-shaped sign with the words "Narrow Bridge" indicate?

A diamond-shaped sign with the words "Narrow Bridge" serves as a warning to drivers that they are approaching a bridge that does not provide enough width for two vehicles to pass safely side by side. This indicates that while the bridge is functional, it may require caution when navigating it, especially if another vehicle is approaching from the opposite direction.

Understanding the meaning of this sign is crucial for ensuring safety on the road, as it prompts drivers to remain vigilant and be prepared to yield or slow down to allow safe crossings. It alerts them to the potential hazard of encountering oncoming traffic on a narrow structure, which could lead to accidents if not approached carefully.

The other options do not accurately describe the "Narrow Bridge" sign. For instance, stating that the bridge cannot accommodate any vehicles or that it is closed misrepresents its function, while mentioning a weight limit changes the focus from width to weight, which is a separate consideration often indicated by different signage.