A grading plan shows contour lines with 2-foot intervals. If you count 5 contour lines between two points, what is the elevation difference?
Correct Answer
C) 10 feet
With 2-foot contour intervals and 5 lines between points, the elevation difference is 5 × 2 = 10 feet.
Why This Is the Correct Answer
When reading topographic or grading plans, contour lines represent lines of equal elevation at specific intervals. With a 2-foot contour interval, each line represents a 2-foot change in elevation from the adjacent line. When counting 5 contour lines between two points, you multiply the number of intervals (5) by the contour interval (2 feet) to get the total elevation difference of 10 feet.
Why the Other Options Are Wrong
Option A: 5 feet
This answer incorrectly assumes each contour line represents 1 foot of elevation change, ignoring the specified 2-foot interval.
Option B: 8 feet
This answer appears to be a miscalculation, possibly confusing the number of lines with the interval spacing or making an arithmetic error.
Option D: 12 feet
This answer incorrectly calculates the elevation difference, possibly by adding extra intervals or misunderstanding the relationship between contour lines and elevation change.
Memory Technique
Remember 'Lines × Interval = Total' - count the contour lines crossed and multiply by the stated interval to get your elevation difference.
Reference Hint
Look up 'Site Work and Grading' or 'Reading Construction Drawings' chapters, specifically sections on topographic maps and contour lines.
More Project Mgmt Questions
What is the minimum R-value required for wall insulation in Florida Climate Zone 2?
A subcontractor brings a new chemical product to your jobsite. Under the Globally Harmonized System (GHS), what information must be immediately available to workers?
A construction site has a trench that is 8 feet deep in Type B soil. What is the maximum allowable slope ratio for the trench walls without protective systems?
A detail drawing shows a scale of 3/4" = 1'-0". If a dimension measures 2.25 inches on the drawing, what is the actual dimension?
What is the maximum recommended spacing between drywall screws when attaching to wood studs?