What is the speed limit at a railroad crossing when visibility is less than 400 feet?

Answer: C — 15 mph

When visibility is less than 400 feet at a railroad crossing, the speed limit is set to 15 mph. This lower speed limit is in place to ensure the safety of both the driver and any pedestrians or vehicles that may also be crossing the tracks. Reduced visibility signifies potential dangers, such as an approaching train that might not be easily seen in time to react. Therefore, a driver is required to approach the crossing cautiously, allowing ample time to stop if necessary. The options reflecting higher speeds, such as 25 mph, 30 mph, or 10 mph, do not align with the crucial need for heightened caution in scenarios where visibility is compromised. A speed of 10 mph might further decrease the risk, but it is not the established limit in this context. Following the 15 mph guideline enhances awareness and response time, contributing significantly to safety at railroad crossings.