North Carolina Building Contractor License Practice Exam

What do contour lines on a grading plan primarily indicate?

1. The reduction of load lost

2. The slope of the terrain

3. The water drainage patterns

4. The depth of soil layers

The correct answer is: The reduction of load lost

Contour lines on a grading plan are utilized primarily to represent the slope of the terrain. These lines connect points of equal elevation and help visualize how the land rises or falls across a particular area. The spacing of the contour lines indicates the steepness of the slope; closely spaced lines signify a steep incline, whereas widely spaced lines suggest a gentle slope. Understanding the slope of the terrain is crucial in construction and land development, as it influences drainage, foundation stability, and overall site design. While contour lines may also indirectly relate to water drainage patterns by showing changes in elevation, their primary function is to illustrate changes in topography rather than specifically detailing drainage. In contrast, the other options pertain to different aspects of site assessment and engineering. The reduction of load lost and the depth of soil layers are important considerations in construction but are not represented by contour lines. These aspects would require separate data and analysis to understand effectively.