General Contractor Practice Exam

What is the elevation at the edge of a 28-foot wide road with a 2% slope and an elevation of 76.5 feet at the crown before the subgrade is put down?

1. 74.72 feet

2. 75.20 feet

3. 75.00 feet

4. 76.00 feet

The correct answer is: 74.72 feet

To find the elevation at the edge of a 28-foot wide road with a 2% slope, it's important to first understand how the slope affects the elevation. The crown of the road is the highest point, which in this case is at an elevation of 76.5 feet. The slope of 2% indicates a drop in elevation as you move away from the crown toward the edge. Given that a 2% slope means that for every 100 horizontal units, there is a 2-foot change in elevation, we can set up the calculation based on the width of the road. Since the road is 28 feet wide, the slope will maintain its ratio over that distance. To find the drop in elevation from the center (where the crown is) to the edge of the road, we need to calculate 2% of the total horizontal distance (which is half of 28 feet since the crown is centered): 1. Half the width of the road is 14 feet. 2. The drop in elevation is calculated by taking 2% of 14 feet: \[ 0.02 \times 14 = 0.28 \text{ feet} \] Now we subtract this drop