ACN–PCN (Aircraft Classification Number–Pavement Classification Number)

ACN–PCN (Aircraft Classification Number–Pavement Classification Number)click for a larger image
A single international method of classifying and reporting pavement bearing strength for aircraft above 12,500 lb (5700 kg) maximum total weight, authorized from the standpoint of the stresses exerted by aircraft loads on pavements. The ACN is a number expressing the relative effect of an aircraft load on a pavement for a specified subgrade strength. The PCN is a number expressing the bearing strength of a pavement for unrestricted operations. A pavement with a particular value can support, without weight restrictions, an aircraft that has an ACN value equal to or less than the pavement's PCN value. The bearing strengths of pavements intended for aircraft of 12,500 lb maximum total weight authorized or less are reported as the maximum allowable weight and maximum allowable tire pressure. Values of PCNs for runways and other aircraft runways are published in the relevant aerodrome publications. A method of representing PCN is indicated in the illustration.
References in periodicals archive ?
Currently, two mathematical models are used in the ACN-PCN method and are known as the Westergaard solution for a loaded elastic plate on a Winkler foundation (interior load case) for rigid pavements, and the Boussinesq solution for stresses and displacements in a homogeneous isotropic elastic half-space under surface loading for flexible pavements (International .
Under the system, a simple two-layer model is adopted for the reaction of an aircraft on a rigid pavement and the model is analysed by Westergaard centre case theory to establish theoretical depth of reference construction of an aircraft on a range of subgrade support values equating to the ACN-PCN method of the ICAO.
The ICAO recommends that the bearing strength of a runway pavement should be reported using the ACN-PCN system indicating the information about the pavement type for ACN-PCN determination, subgrade strength category, and the maximum allowable tyre pressure category.