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84 Implementation of preservation guidelines. The preservation ratings for each treatment into an overall score. The overall guidelines developed in this study are a useful tool for high- scores of the treatments could be examined to identify fea- way agencies to identify candidate high-volume roadways sible treatments--those with scores greater than or equal to suitable for pavement preservation and to select appropri- a weighted 3. ate pavement preservation treatments. A wealth of informa- Develop improved estimates of treatment performance on tion is included in the guidelines regarding the applicability high-traffic-volume roadways. The expected performance and limitations of the various pavement preservation treat- ranges developed in this study are derived from estimates ments and the process by which preservation treatments provided in the literature. Some estimates represent treat- should be evaluated for selection at the project level. Agen- ment life, while others represent extensions in pavement cies interested in implementing the guidelines can expect service life. As mentioned throughout this report, the appro- to encounter a variety of issues that may hinder the imple- priate representation of treatment performance is the exten- mentation process. The most significant barriers entail sion in pavement service life. While it will be incumbent institutional resistance to the use of certain treatments on upon an implementing agency to establish its own estimates high-volume roads, the ability to convince elected govern- of treatment performance, the performance ranges pre- ment officials and the traveling public of the importance of sented in this report need to be improved by incorporating preserving good roads while some bad roads go untouched, pavement life extension data as it becomes available. and the external tug-of-war between competing pavement Investigate more fully the impact of pavement condition, traf- industry groups. Furthermore, because of their nature, a fic level, and climatic condition on treatment performance. single failure on a higher-traffic-volume roadway can offset Although implementing agencies will be tasked with evalu- one hundred successes. At the roadway level, implementa- ating and developing quantified estimates of treatment per- tion is advanced by monitoring and documenting the ben- formance for different pavement conditions, traffic levels, efits of preservation. At the organizational level, experienced and climate conditions, further research is needed at the individuals within the agency championing the preservation national level, along the lines of the LTPP SPS-3 and SPS-4 program also play an important role in implementation. studies. Such research should include more treatment types (including little-used but promising treatments and new or One of the objectives of this project was to identify prom- innovative treatments), cover the various climatic zones, ising strategies or strategies that are not widely used that have and stratify according to specific pavement type (e.g., com- the potential to be effective preservation treatments. These posite vs. flexible, jointed vs. continuous), different ranges did not readily emerge from the literature review, outreach to of high traffic volume (e.g., 5,000 to 25,000 vpd, 25,000 to industry and overseas contacts, or the surveys of agency prac- 50,000 vpd, 50,000 vpd), highway setting (urban vs. rural), tice. However, the collected information clearly identifies and overall pavement condition (e.g., 65 PCR < 75, 75 some treatments that are used on high-traffic-volume road- PCR < 85, PCR 85) or serviceability/roughness. ways by some agencies that others would not consider using. Develop improved estimates of treatment unit costs. The Agencies interested in extending their practice in many cases treatment unit cost ranges provided are based on cost infor- need look no further than the accepted practice of others. mation contained in the literature. The cost ranges have been adjusted upward slightly, because the source data are a few years old. Although costs vary significantly from agency Recommendations to agency and from project to project, a detailed evaluation Although an enormous amount of information on pavement of current costs would provide a better sense of the relative preservation and preservation-related topics was gathered costs among treatments and would better capture the effects and analyzed in this study, there are still technical gaps in the of increased oil prices in recent years. treatment selection process that need to be addressed. Pro- vided below is a list of the most pressing issues and recom- It is noted that the conclusions and recommendations pre- mendations for addressing them in the future. sented herein in many ways mirror the pavement preservation research needs priorities identified in the FHWA's system Develop a more comprehensive treatment-condition match- preservation road map (FHWA 2008). While the problem ing matrix. Such a matrix might use applicability ratings statements in that document are not specifically aimed at (1-to-5 scale, with 1 being nonapplicable, 3 being gener- preservation for high-traffic-volume roadways, the mix of top- ally applicable, and 5 being very applicable) that define ics identified as the highest priority are similar to needs identi- how well a treatment addresses specific distress measures fied in this research. It is reasonable to conclude that as the (i.e., a given distress type, severity level, and extent) and research needs identified in the road map are addressed, and if other condition parameters (i.e., overall condition, smooth- attention is paid in particular to high-traffic-volume roadways ness, friction, noise, and splash-spray). It would also use a as considered in this research, then the practice of preservation weighting process to aggregate the individual applicability on high-traffic-volume roadways will continue to advance.