Load-Equivalency Factors Based on Extended California Bearing Ratio Method

Abstract

The use of load-equivalency factors (LEFs) in pavement design is well established and represents a major factor in various design procedures. The use of the most commonly known AASHTO LEFs in the Israeli design method, however, leads to an underdesign of approximately 10 percent in pavement thickness or to a reduction of 70 percent in design life. New LEF values were developed to be compatible with this design method. This was achieved, first, by attaining straightforward regression equations that are fully compatible with the original total thickness equations given in the Israeli design method (through the MOD software). The built-in LEF values then were calculated by using these regression equations. A comparison was made with LEF values obtained by other established values, and the effect of these values on several overloading issues was evaluated. The conclusion is that the LEFs obtained are the most critical values leading to a substantial reduction in service life or to a substantial increase in the required thickness from overloading.