EQUIVALENT AXLE LOAD FACTORS FOR DESIGN OF RIGID PAVEMENTS DERIVED FROM FATIGUE CRITERIA

This paper presents determination of equivalent axle load factors for rigid pavements on the basis of fatigue criteria used in mechanistic-empirical methods of pavement design. Fatigue criteria for selected methods of rigid pavement design and analysis are presented. These criteria were used to derive the formulas to calculate equivalent axle load factors. It was found that formulas derived for rigid pavements are much more complex than the well known "fourth power equation". The equivalency factors depend on the slab thickness and bending strength of cement concrete and other pavement parameters. There are considerable differences between the equivalent axle load factors derived from different fatigue criteria used in various design methods. The presented analysis indicates that traffic analysis and fatigue criteria should be interrelated.