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9 Industry and agencies are constantly identifying new not be forecast. Other factors that may influence the treat- approaches to treating pavements, while discarding others ment selection process include the extent of snow plowing, that have been shown not to work for them. Key components the use of studded tires or chains, and the lane closure time in an agency's decision process for selecting a specific treat- available to complete the work. ment are (1) determining timing and (2) understanding impor- Traffic is another important consideration as treatments tant attributes of the treatment. In a methodical approach to perform differently under traffic loads. Many agencies differ- identifying appropriate treatments, the performance charac- entiate appropriate treatments based on daily traffic counts or teristics or attributes of the treatments must be considered loads. This information can serve several purposes. For some because these alone determine if a treatment can serve its treatments, the higher volume of traffic contributes to a like- intended purpose. lihood of vehicle damage. Other treatments might be chosen because high-traffic volumes are anticipated and the treat- ment may reduce the likelihood of pavement deterioration. Treatment Attributes The condition of the pavement cannot be ignored in deter- mining appropriate treatments. While the concept of preven- Treatments that are suitable for use by a given agency can tive maintenance implies that the pavement exhibits minimal be identified by considering the following factors or treat- distresses, the reality is that many treatments will be applied ment attributes: to pavements with some distress. It is important to know what distresses are present and how the different treatments will Purpose of the treatment perform in relation to those distresses. Applicability Traffic Environment Contraindications Pavement condition Contraindications Conditions under which a specific treatment simply will not Construction considerations work or should not be used are considered contraindications Expected performance and cost for this treatment. For example, the need for a complete clo- Customer satisfaction sure of the pavement, the requirement for cure time after appli- cation and before loads can be applied, the potential damage from early application of heavy loads, and the possible failure Purpose of the Treatment because of the presence of moisture during construction might all be considered contraindications to the use of certain treat- The purpose of the treatment involves identifying pave- ments. While improvements in the technology of many pre- ment conditions that the treatment is meant to prevent or cor- ventive maintenance treatments help extend the conditions rect. For example, sealing cracks prevents moisture (and under which they can be used, familiarity with their limitations debris) from infiltrating the pavement structure. Some treat- also helps to obtain the best possible performance. ments may serve several purposes; a slurry seal can protect an HMA surface from environmental effects, improve sur- face friction, or seal minor cracks in the pavement surface. Construction Considerations Any treatment considered for a preventive maintenance pro- gram should address one or more specific purposes so that the Constructibility issues that need to be considered include conditions of its use are clear. Because some of the preven- the complexity of the construction of the treatment, the need tive maintenance treatments are applied to pavement with lit- for specialized or well-calibrated equipment, the local avail- tle or no signs of deterioration, the purpose is not always to ability of qualified contractors, and the need for specialized correct distress. materials. If a treatment's success relies on factors that are beyond the control of the agency, its application may be viewed as less feasible than a treatment that can be placed by most contractors using locally available materials. Applicability The applicability or appropriateness of a treatment is deter- mined by the overall condition of the pavement, traffic, and Expected Performance and Cost environment for which the treatment is suited. For example, some treatments require application at fairly warm tempera- Another set of considerations relates to the performance and tures to ensure good long-term performance, and their use is cost associated with a given treatment. An agency should be not recommended if a prolonged period of warm weather can- aware of both the expected performance of the treatment and