Stress Repetitions in Pavement Design

If repetitions of stress or load are now (as of 1965) important in pavement design, they must always have been important in design; they have not suddenly become significant, when they were not formerly so, because of a recent research finding or other technical development. In fact, many designers have long recognized the need to differentiate between heavily and lightly trafficked pavements in regard to design strengths. It is true, however, that recent findings and developments are making inadequate the mere recognition of such categories as heavily traveled or primary. Past methods and knowledge requiring only crude determinations of stress repetition will no longer suffice. Although precise determinations of stress repetitions may not be possible, future progress demands better means of realistically determining quantities and effects of load repetitions. Various problem areas involved in determining quantities and effects of stress repetitions are delineated.