# Complex Method of Airfield Pavement Condition Evaluation Based on APCI Index
## 3 Method of the Military University of Technology  
Another known approach to technical condition evaluation of airfields functional elements is a methodology developed in the Military University of Technology. With the parameters mentioned in Section 1, it can be used for the pavement condition evaluation and planned maintenance projects. A damage indicator is calculated depending on the type of airfield pavements. For airfield pavements made in cement concrete technology, it is designated from the following Equation (4) [26; 27]:  
\[Z_{B}=\frac{1}{A}(1.8\cdot U_{1}+1.22\cdot U_{2}+U_{3}+U_{4}+U_{5}), \tag{4}\]  
where: \(Z_{B}\) is an index of damage to the airfield pavements made from cement concrete; \(U_{1}\) is the surface of cracks and felled corners [m\({}^{2}\)]; \(U_{2}\) is the surface of cracks and pavement crushes [m\({}^{2}\)]; \(U_{3}\) is the surface of the pavement exfoliations [m\({}^{2}\)]; \(U_{4}\) is the surface of multiple cracks of pavements [m\({}^{2}\)]; \(U_{5}\) is the surface of marl cavities in the pavement surface [m\({}^{2}\)]; \(A\) is a total surface of the pavement [m\({}^{2}\)]. On the other hand, the index of damage for airfield pavements made in asphalt concrete technology is designated from the following Equation (5) [26; 27]:  
\[Z_{N}=\frac{1}{A}(B_{1}+B_{2}+B_{3}+B_{4}+B_{5}), \tag{5}\]  
where: \(Z_{n}\) is an indicator of damage to the airfield pavement from asphalt concrete; \(B_{1}\) is the surface of blisters [m\({}^{2}\)]; \(B_{2}\) is the surface of the chipping or loosening [m\({}^{2}\)]; \(B_{3}\) is the surface of the pavement cancers [m\({}^{2}\)]; \(B_{4}\) is a surface of heaves or fractures [m\({}^{2}\)]; \(B_{5}\) is the surface of longitudinal and transverse cracks [m\({}^{2}\)]; and \(A\) is the total surface of the pavement [m\({}^{2}\)]. If you need to determine the degree of technical use of the airfield pavement in a given time interval, you can use an indicator calculated from Equation (6) [26; 27]:  
\[D=Z-Z_{p}-N, \tag{6}\]  
where: \(Z\) is an indicator of damage in a given time unit; \(Z_{p}\) is an indicator of damage that occurred earlier; and \(N\) is an indicator of repairs in a given time unit. On the other hand, the repair rate in a given unit is calculated from the ratio of surface on which repairs were made to the entire surface of the assessed airfield functional element from the following Equation (7) [26; 27]:  
\[N=\frac{R}{A}\cdot 100, \tag{7}\]  
where: \(R\) is a repaired surface [m\({}^{2}\)]; and \(A\) is a reference surface (slab or tested area) [m\({}^{2}\)]. The methodology presented above [26; 27] gives a set of classification parameters for the listed indicators, pavement evenness and friction criteria. This set does not include the load capacity parameter due to the fact that the load capacity is a decisive indicator and must be considered separately in the maintenance strategy. The grade of the surface according to the listed operating parameters is presented in Table 1 [27; 28]. The evaluation of the airfield pavement condition based on the criteria given in Table 1 can be unambiguous if the assessment indicators of individual features will cover. More often, the situation deviates from such a state, and the assessment of the surface of the pavement can be determined in such a case by means of an independent indicator Y [-], calculated therefore from the following Equation (8) [26; 27]:  
\[\mathrm{Y}=8\cdot Z-6.66\cdot S+0.89\cdot R_{L}+13.3\cdot D+8.9\cdot N+2.955, \tag{8}\]  
where: \(Z\) is an indicator of damage [%]; \(D\) is an indicator of technical consumption (degradation) [%]; \(N\) is a repair indicator [%]; \(S\) is the friction of the surface expressed by the coefficient of friction \(\mu\) [-]; and \(R_{L}\) is the surface evenness in the longitudinal direction measured with a lath of 4 m length [mm].