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27 CHAPTER SIX PRIORITIZATION, PLANNING, AND BUDGETING This section outlines how M&R needs are prioritized, sched- The first step in the prioritization is the assignment of a uled for implementation through programming, and then priority level to each M&R treatment on the list of treatments molded into a budget for a CIP (Wade et al. 2007b). Also representing the unlimited budget. The priority level reflects described is the computer software that facilitates the identi- the main reason why the treatment is recommended for fication of M&R needs and prioritization. implementation. The priority levels are related to the levels of service used to identify M&R needs and include safety, The listing of all M&R needs, such as those shown in critical, cost-effectiveness, and target-priority levels. Tables 9 and 10 in chapter five, represent an unlimited budget. The unlimited budget will change for the following reasons: a) Safety Level Prioritization--The safety priority level is the highest priority for airport pavement maintenance · Economic considerations. Not all M&R treatments can and includes M&R treatments that are needed to main- be carried out to the extent and at the time recom- tain safe operation of aircraft. In general, this level mended by the unlimited budget because of financial includes projects to meet safety and regulatory require- constraints. ments mandated by the FAA and environmental agen- · Operational considerations. Scheduling of the projects cies. In the pavement area, the safety priority level may avoids interfering with airport operation. It is particularly include, for example, M&R treatments for an AC sec- important for scheduling work on runways and taxiways tion with raveling surface resulting in FOD or a runway that provide service that cannot be picked up by alterna- with inadequate pavement friction. Because treatments tive facilities. Other operational concerns include safety in this category are obligatory, it can also include car- issues, airlines' operations, and allowable closures. ryover projects (already approved projects and projects · Other construction work. Pavement preservation work that are in progress and need additional funding). is typically coordinated with other airfield maintenance b) Critical Level Prioritization--The critical priority and construction activities. For example, during the level includes M&R treatments that are necessary to replacement of an in-pavement lighting system on a provide or maintain a minimum acceptable level of runway, pavement preservation work can be carried out service. on a parallel taxiway. c) Cost-effectiveness Level Prioritization--This level · Construction capacity. The schedule may need to take includes projects where implementation timing is into account capabilities of the local construction indus- important to achieve cost-effectiveness. Typically, this try and the capability of the airport agency to manage level includes preventive maintenance projects, such construction work. as joint resealing, carried out before more significant damage occurs. Approximately 29% of the responding airports indicated that they implement preventive PRIORITIZATION maintenance treatments at the right time, and about 57% of airports noted that they sometimes implement The prioritization of needs is described for the same two sce- preventive maintenance treatments at the right time narios used for the identification of needs--short-term plan- (Figure 17). ning and long-term planning. d) Target Level Prioritization--Target level includes proj- ects to maintain or achieve the target level of service. Prioritization for Short-Term Planning Projects that belong to the critical level and apply to run- Short-term planning supports only limited prediction of ways would have higher priority than projects that belong to future network conditions without considering alternative the cost-effectiveness level and apply to taxiways. future pavement conditions resulting from M&R treatments. The historical and predicted condition of the pavement net- It is easier and preferable to prioritize projects that belong work can be used to evaluate the adequacy of different pave- to the same priority level and functional class than to priori- ment preservation budgets. It is also possible to use the back- tize projects across priority levels and functional classes. Pri- log of projects as an indication of desirable funding levels. oritization across functional classes, for the same priority
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28 tiveness and the net present value--defined in the section on Percent of respondents 60 Prioritization for Long-Term Planning. 40 20 Inclusion of Preventive Maintenance 0 Preventive maintenance reinforces the concept of the right Yes Sometimes No treatment on the right pavement at the right time. According Implementation of preventive maintenance to the survey, about 29% of agencies reported that they FIGURE 17 Implementation of implement preventive maintenance treatments at the right preventive maintenance treatments at time (see Figure 17). For comparison, a 1999 survey of state the right time. transportation agencies, carried out by the AASHTO Pave- ment Preservation Lead State Team (2000), reported that 85% of the 41 agencies that responded to the survey have level, can be facilitated by developing priority rankings of established a preventive pavement maintenance program. the type shown in Table 11. The highest ranking, in this sim- Systematic implementation of preventive maintenance treat- plified example, is assigned to runways serving a high num- ments may represent a shift in the way the pavement preser- ber of aircraft operations. vation is done. The selection of sections for M&R is not done using a worst-condition-first approach, but by selecting sec- Prioritization can be based on a single characteristic such tions where an M&R treatment would be most cost-effective. as PCI or on a composite indicator that combines the influ- Often, the most cost-effective treatment is a preventive main- ence of several characteristics. tenance treatment. At the same time, agencies still have to maintain pavements to provide safe operation of the aircraft An example of prioritization of M&R treatments for 271 and provide a minimum level of service. pavement sections using a composite priority indicator was provided by Tighe et al. (2004). The composite priority indi- A systematic application of a preventive maintenance pro- cator combines the influence of four factors: gram for airport pavements has not been well-documented. Most of the experience has been reported by state highway 1. PCI of the section. This factor represents pavement agencies as it applies to highway pavements (Geoffroy 1996; characteristics and was assigned the highest weight- Zimmerman and Wolters 2003). The Foundation for Pavement ing. In general, other pavement characteristics that can Preservation (2001) developed useful guidelines for launching be used include a friction index and FOD potential. a preventive maintenance program and outlined the need to 2. Number of annual aircraft departures taking off from establish the overall strategies and goals of the program. the section. This factor represents volume of aircraft movements and can be alternatively represented by, Prioritization for Long-Term Planning for example, the total number of aircraft operations. 3. Functional class of the section (runway, taxiway, Multi-year prioritization of alternative treatments is typically apron). based on cost-effectiveness. Cost-effectiveness is the ratio of 4. Operational importance of the section (primary, sec- the effectiveness (benefits) and costs for individual M&R ondary, or tertiary). For example, a runway may be pri- treatments. The cost of the treatment is based on life-cycle mary or secondary; an apron may be primary, sec- costs as much as possible (Zimmerman et al. 2000). The effec- ondary, or tertiary. tiveness for an airport pavement section can be calculated by multiplying (1) the area under the pavement performance Another factor that can be incorporated into a composite curve, (2) the number of aircraft departures, and (3) the area of priority indicator is cost-effectiveness--the ratio of effec- the pavement section (Tighe et al. 2004). TABLE 11 PRIORITY RANKING BY FUNCTIONAL CLASS AND TRAFFIC Aircraft Operations or Usage Priority Rank Functional Class High Medium Low Runways 1 2 4 Taxiways 3 5 7 Aprons 6 8 9