1. Highway Engineering CE 431
Resistances
Eng. Ali Mohammed Babalghaith

2. Types of resistance: Inertial resistance Grade resistance
Rolling resistance
Curve resistance
Air resistance

3. 1- Inertial resistance :-
Page 118

4. 2- Grade resistance:-
Page 118
Grade +2% 2
100
Page 119

5. 3- Rolling resistance:-
Page 119

6. 4- Curve resistance:-
Page 119

7. 5- Air resistance:-
Page 120

8. Power Requirement:-
Page 120

9. Problem 5.6 : page 122
5.6 Estimate the horsepower required to accelerate a 2,500-lb vehicle traveling 30 mph up a 5.0 percent grade at a rate of 6 ft/sec2. The vehicle has a frontal cross-section area of 20 ft2. The roadway has straight alignment and a badly broken and patched asphalt surface. Assume the drag coefficient = 0.3.
Given :
Horsepower = ???
Vehicle weight = 2500 lb
speed = 30 mph
grade = +5%
acceleration rate = 6 ft/sec2
Frontal cross-sectional area = 20 ft2
drag coefficient = 0.3
No Horizontal curve

10. Solution:-
1- Inertial resistance :-

11. Solution:-
2- Grade resistance :-

12. Solution:-
3- Rolling resistance :-
From table page 119

13. Solution:- No Horizontal curve Fc = 0.00 4- Curve resistance :-
Curve Resistance is not needed (value of zero) since the road is straight
No Horizontal curve
Fc = 0.00

14. Solution:-
5- Air resistance :-

15. Solution:-
Power Requirements :-