NICET - Highway Construction Inspection Practice Exam

The external distance formula helps to calculate:

1. Total length of a straight section

2. Off-set distance from the arc

3. Distance from the tangent to the arc

4. Volume of earthwork required

The correct answer is: Distance from the tangent to the arc

The external distance formula is utilized in surveying and highway construction to determine the distance from the tangent to the arc of a circular curve. This is particularly important in designing roadways or railways where curves are incorporated, as it aids in the precise placement and alignment of road features. When calculating the external distance, one is primarily interested in understanding how far the outer edge of the circular arc is from the line of tangency. This information is crucial for ensuring that the curve is properly aligned with its associated tangent lines, which directly affects vehicle handling and safety. In contrast, while the total length of a straight section and the offset distance from the arc are relevant to roadway design, they are calculated differently and do not directly involve the concept of external distance. The volume of earthwork required relates to the amount of material that must be moved for construction but is not determined using the external distance formula.