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OCR for page 63
63 applied preventive maintenance treatments or monitored sub- Relating measured material properties to pavement per- sequent performance in a manner that generated the needed formance--While many agencies focus on conventional data. In the absence of such data and if the implementation of distress indicators to identify the optimal time to apply an optimal timing approach is desired, test sections must be preventive maintenance, other meaningful performance constructed and monitored over time. Guidelines for construct- measures that reflect the benefits of applying preventive ing and monitoring test sections are presented in Appendix D. maintenance might be used. Examples of these measures are asphalt viscosity, surface texture, and pavement mois- ture content or infiltration. APPROPRIATE MEASURES Planning and monitoring test sections--Agencies are OF PERFORMANCE strongly encouraged to construct preventive maintenance test sections using treatments of local interest placed at The process of identifying and tracking appropriate mea- different times to generate optimal timing data; monitor- sures of performance is a key component of the optimal tim- ing the performance over a long enough time is necessary ing analysis. An appropriate measure is one that reflects the to generate differences in performance. benefit of using the treatment; preferably it relates to the iden- Enhancing the optimal timing methodology--When more tified program objectives (e.g., if customer satisfaction is a time-series performance data for pavements receiving preventive maintenance program objective, then pavement preventive maintenance treatments at different times roughness could be used as a performance measure). In mon- become available either from agency databases or from itoring treatment performance, it is also important to recog- experimental sections, the optimal timing methodology nize that a treatment can "last" much longer than it provides should be further evaluated and enhanced. a benefit. Ultimately treatment performance (or true treat- Developing a guide on optimal timing--When sufficient ment "life") is determined by the time at which the treated results are available from agencies across the country, a pavement's performance reverts to the do-nothing condition, guide could be developed to assist agencies which have or when it reaches a defined threshold. neither the performance experience nor the means to construct and monitor test sections to identify optimal timing based on the experiences of others. DATA ANALYSIS AND SELECTION Programming a more robust, stand-alone software tool-- OF OPTIMAL TIMING The tool could expand on the methodology developed in this project to facilitate more comprehensive analy- Whether preventive maintenance treatment performance ses by including the following: data come from existing databases or test sections, the proper Ability to analyze preventive maintenance strategies analysis of the data identifies the optimal time to apply such (i.e., more than one preventive maintenance treat- treatments. The optimal timing methodology described in ment application) rather than the application of one Chapter 3 and Appendix C is incorporated in OPTime. treatment, (Appendix C is available to users by accessing the NCHRP Use of a true optimization method in which all possi- website: http://trb.org/news/blurb_detail.asp?id=4306). The ble treatment strategy timings are analyzed, and output of the analyses is presented in tables and charts to help Ability to include multiple treatment types to help esti- to understand the findings and identify the sensitivity of the mate the most effective treatment type and its associ- treatment's performance to different treatment application ated optimal timing. timings. Conducting training workshops--Training on the appli- cation of the methodology and the use of the analysis SUGGESTIONS FOR ADDITIONAL RESEARCH tool will facilitate its use. Such training could be offered on a regional basis or to individual highway agencies. In For agencies that intend to implement or improve their the latter option, an agency's pavement performance data preventive maintenance practices, there is a need for research could be used to demonstrate the applicability of these efforts to develop guidance on issues related to optimal tim- data to the optimal timing methodology or the need for ing, including the following: other types of data.