Which sight distance is specifically related to the distance needed to stop a vehicle safely?

• A. Passing Sight Distance
• B. Decision Sight Distance
• C. Stopping Sight Distance
• D. Intersection Sight Distance

Answer: (C)

Stopping Sight Distance is the key distance related to the ability to stop a vehicle safely. It is defined as the minimum distance required for a driver to perceive a need to stop and bring the vehicle to a complete halt without colliding with an obstacle. This distance considers factors like the perception-reaction time of the driver, deceleration rate of the vehicle, and the speed at which the vehicle is traveling.

Stopping Sight Distance is critical in transportation design, as it ensures that roadways provide sufficient visibility and clearance for drivers to react to potential hazards. It encompasses both the distance needed for the driver to recognize an obstacle and the actual distance required for the vehicle to come to a stop safely. Therefore, this measurement is essential for designing horizontal and vertical curves in roads and other elements of roadway design to enhance safety for all users.

In contrast, Passing Sight Distance relates to the distance necessary for a driver to safely complete a passing maneuver on a two-lane roadway without interfering with oncoming traffic. Decision Sight Distance is focused on the distance required for a driver to make a decision about an upcoming situation, like entering an intersection. Intersection Sight Distance involves the visibility requirements for drivers at intersections to see conflicting traffic and other potential hazards. Each of these distances serves its own purpose