NICET - Highway Construction Inspection Practice Exam

When calculating slope, what is the method used?

1. Elevation change divided by distance

2. Distance divided by elevation change

3. Total area divided by contour interval

4. Elevation times distance

The correct answer is: Elevation change divided by distance

The method for calculating slope is based on the ratio of the change in elevation to the horizontal distance over which that change occurs. This is expressed mathematically as elevation change divided by distance. Slope is a measure of how steep a surface is, and it is typically represented as a percentage or a ratio. When determining terrain or roadway design, knowing the slope is critical for various factors including drainage, stability, and safety. For instance, a steeper slope can affect runoff patterns and pose risks for erosion, while a gentle slope may be more manageable for vehicles and pedestrians. The other methods mentioned do not represent the conventional calculation of slope. Dividing distance by elevation change would yield a value that represents a different geometric relationship, while calculating total area divided by contour interval does not directly address slope. Elevation times distance does not correspond to a relevant measurement of steepness; instead, it combines two different dimensions without yielding slope. Therefore, elevation change divided by distance is the correct and conventional method for calculating slope.