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13 Objectivity and consistency--Objective and consis- EVALUATION OF PAVEMENT CONDITION tent pavement evaluation produces true trends and pro- vides reliable data for pavement investment decisions. The following pavement characteristics are evaluated for in- Objectivity and consistency of repeated evaluations service airfield pavements enables airport owners to see how the pavement condi- tions change over the years. They also enable funding Pavement surface distress agencies to compare pavement conditions of different Pavement roughness airports within and outside their jurisdiction. Pavement friction Timelines and relevancy--Pavement evaluations sup- Presence of foreign object debris port planning and budgeting cycles and provide data for Pavement structural strength or capacity. timely implementation of pavement preservation treat- ments, particularly preventive maintenance treatments. Pavement Surface Distress Long-term monitoring--Historical pavement perfor- mance data from repeated evaluations are vital for the Surface distresses of airport pavements are typically evalu- development of pavement performance models used to ated using the PCI. The PCI evaluation methodology was estimate when M&R treatments will be needed. Long- developed by the U.S. Army Corps of Engineers and is term monitoring data also enables evaluation of past described in FAA Advisory Circular on Guidelines and Pro- performance of pavement preservation treatments. cedures for Maintenance of Airport Pavements (2007) and in Cost-effectiveness--Collection of pavement evaluation ASTM Standard D5340 (2003). It is noteworthy that ASTM data in the field can be expensive. The type, amount, and adopted the PCI as a pavement condition rating standard for the frequency of data collection are affected by cost- airfield pavements. The PCI values can range from 0 to 100 effectiveness considerations. and be interpreted as shown in Table 1. Frequency of evaluation--Public Law 103-305 (1994) states that if an airport is conducting a PCI assessment as PCI distress data are obtained by a visual survey carried part of pavement management activities, a 3-year inspec- out by trained pavement evaluators who walk on the pave- tion cycle is sufficient. However, the 3-year cycle may be ment. Alternatively, the evaluation can be done by taking high- too long for selecting and implementing preventive main- quality pavement images and interpreting them using pave- tenance treatments in a timely manner. ment evaluators or specialized software. The PCI is based on Network- and project-level evaluation--There is a the evaluation of distress type, severity, and quantity. difference between pavement evaluation data at net- work and project levels. Network-level management Distress type--There are 16 pavement surface distress entails periodic surveys of pavement surface distresses types for AC pavements and 15 for PCC pavements. and pavement friction on sample units. Project-level Considering pavement preservation needs, prominent pavement management typically involves detailed eval- distresses for AC pavements include longitudinal and uation of pavement surface conditions over the entire transverse cracking, rutting, weathering and raveling, project area and the evaluation of pavement load capac- and block cracking. Also included are two distresses ity through nondestructive testing (e.g., deflection, cone specifically related to airport operations--jet blast and penetrometer, and ground penetrating radar) and destruc- oil spillage. For PCC pavements, prominent distresses tive testing (e.g., coring and boring and subsequent include joint seal damage, joint spalling, faulting, corner material testing). break, and linear cracking. TABLE 1 PAVEMENT CONDITION INDEX FOR AIRPORT PAVEMENTS Applicable Pavement Preservation PCI Rating Description Treatments 86100 Good--only minor distresses Routine maintenance only 7185 Satisfactory--low and medium distresses Preventive maintenance 5670 Fair, some distresses are severe Corrective maintenance and rehabilitation 4155 Poor--severity of some of the distresses can Rehabilitation or reconstruction cause operational problems 2640 Very poor--severe distresses cause Rehabilitation and reconstruction operational problems. 1125 Serious--many severe distresses cause Immediate repairs and reconstruction operational restrictions 010 Failed--pavement deterioration prevents safe Reconstruction aircraft operations

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14 Severity of pavement surface distress--There are four distress surveys for all airports under their jurisdiction using the severity levels defined for most of the pavement distress PCI procedure. For example, all 50 public airports in Michigan types--none, low, medium, and high. The severity rating are evaluated using the PCI methodology (Michigan Airports is facilitated by a systematic description of the severity Division 2007). levels and by photographs illustrating the differences between the levels. For project-level analysis, the evaluation of surface dis- Quantity of pavement distress--Quantities are mea- tresses typically uses the same rating as that used for the net- sured in feet or in square feet of the affected area. work level. However, the entire section is evaluated instead of only sample units. Evaluation Methodology Roughness The distress assessment is done only on selected sample units. The results for sample units are averaged and the average result The FAA defines profile roughness as surface profile devia- is reported for the entire section. The sample units are of a tions over a portion of the runway that may increase fatigue uniform size and selected by statistical sampling. The number on airplane components, reduce braking action, impair cock- of sampling units is chosen to achieve the desired accuracy pit operations, and/or cause discomfort to passengers. The and reliability. interaction between aircraft responses and runway pavement roughness is complex and depends on the type, weight, and The major advantages of the PCI procedure are its wide speed of aircraft, and on the position of the observer in the use, objectivity, and acceptance. A PCI rating provides a good aircraft (Woods and Papagiannakis 2009). Traditionally, indication of the functional serviceability of the pavement and M&R actions designed to improve pavement smoothness have basic information about its structural integrity. A PCI rating been based on pilot observations and complaints (Larkin and alone can be used to estimate M&R needs for planning pur- Hayhoe 2009). poses. The advantages as well as potential misconceptions and pitfalls of using the PCI procedure for airfield pavements For newly constructed airport pavements, procedures for have been described by Broten and De Sombre (2001). measuring and specifying pavement roughness have been developed and accepted. For in-service pavements, a first As described in Table 2, 78% of all airports surveyed step toward defining and implementing pavement roughness carry out periodic PCI surveys on the runways, with an aver- criteria is provided by FAA Advisory Circular on Guidelines age frequency of every 3.4 years. The PCI surveys are done even by airports that do not have a formal PMS, and are and Procedures for Measuring Airfield Pavement Roughness sometimes done by state aviation administrations on behalf (2009). The roughness criteria presented in the current ver- of the individual airports. Only one airport used an internal sion of the Circular are intended to address isolated bump method to evaluate pavement surface distresses, and 10% of events and do not address cyclic or harmonic events that can airports did not carry out any periodic pavement evaluation. have a substantial impact on airplane occupants, components, Table 2 also notes that 54% of survey respondents use the and operations. PCI for taxiways and other facilities, with average frequen- cies of every 3.3 years. Information on the use of other types The FAA also developed an inertial profiling system for of pavement characteristics is also described. In addition, measuring runway and taxiway longitudinal elevation profiles several airport agencies reported using digital images to doc- and a computer program, Profile Federal Aviation Administra- ument pavement surface distresses. tion (ProFAA), to analyze the measured profiles. The ProFAA can be used to compute a variety of airport pavement roughness Most state aviation agencies, such as those in Ohio, Michi- indices from the measured profiles, including the Boeing Bump gan, Washington, Montana, and Oregon, carry out periodic Index and the International Roughness Index. TABLE 2 EVALUATION OF PAVEMENT CHARACTERISTICS Runways Taxiways and Other Facilities Pavement Characteristic Usage Average Usage Average (%) Frequency, years (%) Frequency, years PCI 78 3.4 54 3.3 Roughness 12 N/A 4 N/A Friction 22 N/A 8 N/A FWD testing 18 3.7 12 N/A Based on the survey. Notes: FWD = Falling Weight Deflectometer; N/A = Data are not available or are insufficient.