Right-of-way width is the sum of the cross section elements such as the number of lanes, shoulders, ditches, and sideslopes. Determine the minimum width of the right of way for a four lane rural highway (two lanes in each direction) with the following dimensions:

- 12–foot lanes at a slope of 2%
- 6-foot shoulders at a slope of 6:1
- Ditch width is 2 feet
- 10-foot foreslopes at a slope of 3:1
- 15-foot backslopes at a slope of 3:1.

The dimensions are measured along the surface of the element.

[Solution shown below]

Solution

Using the pythagorean theorem, the width required for 4 lanes is 4*(12/(12+.022)1/2) = 48 feet. Using the same procedure for the remaining elements:

Shoulder width = 2*(6/(12+(1/6)2)1/2) = 11.8 feet

Ditch width = 2*2 = 4 feet

Foreslope width = 2*(10/(12+(1/3)2)1/2) = 19 feet

Backslope width = 2*(15/(12+(1/3)2)1/2) = 28.5 feet