Why is the driver's eye height for large trucks specifically cited in roadway design standards?

• A. To ensure adequate headroom
• B. For determining necessary signage
• C. To calculate sight distance
• D. For vehicle registration purposes

Answer: (C)

The driver's eye height for large trucks is specifically cited in roadway design standards primarily to calculate sight distance. This is crucial in ensuring that drivers of large vehicles have a clear and unobstructed view of the roadway, other vehicles, pedestrians, and any potential hazards.

Calculating sight distance takes into account the height of the driver's eye, as this measurement affects how far a driver can see and subsequently react to obstacles or changes in the road conditions. For large trucks, which have a higher center of gravity and different visibility levels compared to passenger cars, using an accurate eye height measurement allows engineers to design roads that accommodate their specific needs, improving overall safety and traffic flow.

In contrast, adequate headroom relates more to tunnel or overpass clearances and isn’t the primary focus for design sight distances. The determination of necessary signage typically involves different criteria, focusing more on visibility and readability rather than directly on driver eye height. Vehicle registration purposes are unrelated to roadway design standards, as they deal with legal and administrative aspects rather than physical design requirements.