Final answer:
The bridge being narrower than the road is a warning to drivers to navigate cautiously due to potential hazards and structural limits of the bridge. Load limits are essential to prevent damage, and expansion joints accommodate temperature-induced length changes.
Step-by-step explanation:
The warning about the bridge being narrower than the road is important for drivers because it informs them of a potential hazard. Bridges may be narrower than the roads leading up to them, which can affect traffic flow and the safety of oversized vehicles. Additionally, bridges have load limits that are critical to adhere to, as exceeding these limits can damage the structure. A narrower bridge also indicates that drivers may need to reduce speed and proceed with caution to adapt to the restricted space. Expansion joints are mentioned to explain that bridges are designed to accommodate changes in length due to temperature variations, ensuring the structure's integrity. Tollbooth stations may have wires in the pavement to detect approaching vehicles, but this is unrelated to the narrower width of the bridge itself.