9.2.7 Grades
Undesirable speed differentials between vehicle types suggest that limiting the rate and length of the grades should be considered. Passenger vehicles are not significantly affected by grades as steep as 3 percent, regardless of initial speed. Grades above 2 percent may affect truck traffic depending on length of grade.
summarizes the maximum grade controls in terms of design speed.
Type of Terrain | Design Speed (mph) | |||
85 | 90 | 95 | 100 | |
Level | 3% | 3% | 3% | 3% |
Rolling | 4% | 4% | 4% | 4% |