Corrugations on Gravel and Lateritic Roads

The paper reviews briefly the various theories on the formation of corrugation and presents a hypothesis on the mode of formation. A mathematical equation for the motion of a simple vehicle on a corrugated road was developed. Field measurements and data were taken to obtain vehicular and road parameters for the developed equations. From the results, the maximum transmission factor obtained when the wheel and axle assembly was vibrating at its natural frequency of 8.6 cycles/sec was 3.0. The transmission factor was 0.014 when the tire was in contact with the ground and moving at the normal operating speed of 50 km/hr. The natural frequency when the tires were in the air was 3.1 cycles/sec. The results also showed that little body response occurred for the average car at speeds greater than 1 km/hr. The developed equations predicted that greater impact forces would be obtained for increases in vehicle mass, spring and tire stiffnesses, but decreases in vehicle damping.