With most of the highway systems in place, emphasis has shifted from design and construction to preservation and expansion. Unfortunately, the engineering skills, knowledge, and experience required to preserve the systems are significantly different than those required to originally design and build the systems. The experience gained in the initial phase, although important, is not in itself sufficient to preserve the systems. Pavement preservation is defined as the sum of all activities undertaken to provide and maintain serviceable roadways. This includes corrective maintenance and preventive maintenance, as well as minor rehabilitation projects. A cost-effective pavement preservation program requires a systematic and comprehensive engineering management of, and a solution to, pavement network problems. Preventive maintenance (PM) is defined by the American Association of State Highway and Transportation Officials as the "planned strategy of cost-effective treatments to an existing roadway system and its appurtenances that preserves the system, retards future deterioration, and maintains or improves the functional condition of the system (without increasing the structural capacity)." Hence, PM actions must be taken on pavements in relatively good condition. The development and implementation of a cost-effective PM program faces several obstacles: political debate, budget constraints, lack of education, and the existing practice of "worst pavements are first." Some state highway agencies have overcome these obstacles, and they are harvesting the success of their PM programs. The state of the practice of three agencies--those of Arizona, Montana, and Pennsylvania--is presented and discussed.
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