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35 mal timing of preventive maintenance treatments by Peshkin struction. For this reason, in addition to the LCCA that takes et al. (2004). A new LCCA guide and software package is into account monetary aspects of cost and benefits, a systematic also being developed under Airfield Asphalt Pavement Tech- assessment of other treatment attributes may also be carried out. nology Program Project 06-06. For example, consider two alternative rehabilitation treat- The methodology of LCCA consists of the following ments for an AC pavement on a runway of a small airport: a steps: traditional overlay and in-place recycling. In addition to the LCCA that may favor in-place recycling, it is advisable to Inclusion of all viable and practical alternative M&R also consider other attributes: treatments. Determination of agency costs for each alternative. The Effectiveness of the two alternatives. Effectiveness is agency costs include the initial construction costs and defined as the area under the pavement performance subsequent M&R costs throughout the analysis period. curve (see Figure 18). Determination of user costs. Many agencies do not Agency experience with the performance of the alter- natives. include user costs in LCCA on the project level, because Availability of qualified contractors. user costs are often similar for all alternatives and do Reliability of cost estimates, particularly if local con- not affect agency budget. However, when construction tractors are not available to carry out a specific alterna- of M&R alternatives may have a different impact on tive M&R treatment. airport operations and revenues, for example because of Environmental and sustainability benefits owing to the differences in the length of construction, user costs recycling of AC pavement material in-place. are included. Potential for future cost savings if a new, less expensive Selection of economic parameters for LCCA in terms of rehabilitation method becomes available. the discount rate and analysis period. Compatibility with phased or off-peak construction Calculation of the net present value of agency costs and requirements. user costs. Selection of the alternative. The alternative with the A step-by-step example of this approach is provided in lowest agency and user costs is the best from the eco- Selecting a Preventive Maintenance Treatment for Flexible nomical point of view. Pavements (Hicks et al. 2000). Briefly, the procedure con- sists of four steps: Cost-effectiveness Evaluation 1. Selection of relevant attributes that are important to the customer and the agency. The list of attributes given in Cost-effectiveness is the ratio and effectiveness (benefits) to the earlier example is only illustrative and does not life-cycle costs. The effectiveness is calculated using a simi- include many other attributes that may be important lar procedure as that used on the network level described in for specific alternatives, such as pavement friction, the section on Prioritization for Long-term Planning, with sensitivity to weather during construction, and avail- the additional benefit of using more reliable project-specific ability of quality materials. data. On the network level, the effectiveness is calculated by 2. Assigning relative importance to the attributes using a multiplying the area under the PCI performance curve by the rating factor. The total score of 100 is distributed to all number of aircraft operations and the surface area of the sec- relevant attributes. tion. The area under the performance curve, considered to be 3. Scoring each attribute in terms of its importance for the a measure of pavement serviceability, is illustrated in Fig- selection of the preferred treatment. This is accom- ure 18 in chapter six. On the project level, the number of air- plished using scoring factors on a 5-point scale, 5 being craft operations and the surface area are the same for all alter- very important, and 1 not important. natives and need not be considered. The cost-effectiveness 4. Calculating total scores for all alternative treatments method provides an improvement over the LCCA method by by summing the product of rating and scoring factors taking into account differences in pavement serviceability obtained for all attributes. provided by different alternatives. PROJECT IMPLEMENTATION AND MONITORING Ranking Evaluation The application of M&R treatments currently considers the Some of the attributes of M&R treatments, such as disruption use of appropriate materials, construction methods, and qual- of airport operations, previous agency experience with the ity control and assurance procedures. Following the trends of treatment, sustainability, or improved pavement friction, can- the highway construction industry, many airports use end- not be readily quantified in monetary terms. M&R treatments result specifications for construction quality control. In addi- may also create additional benefits in the form of improved tion to quality control and quality assurance procedures, air- pavement surface or impose operational constraints during con- port operators also use construction warranties. Warranties

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36 provide a catch-all provision to ensure basic construction evaluate periodically specific pavement M&R treatments, quality. Warranties are particularly important for pavement particularly treatments that are not routinely used. This maintenance treatments where the construction materials and enables the airport pavement manager to expand, modify, or procedures are difficult to specify and enforce. discontinue specific treatments based on their documented field effectiveness. According to data presented in Figure 6 (in In addition to the periodic condition evaluation of the chapter two), only 45% of agencies reported using an APMS entire pavement network, discussed in chapter four, airports to determine the performance of the past M&R treatments.