pavement classification number


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pavement classification number (PCN)

pavement classification number (PCN)click for a larger image
A number expressing the bearing strength of a pavement for unrestricted operation (ICAO). PCNs are calculated in terms of a standard single-wheel load. The values of PCNs for runways and other operating areas are published in relevant aerodrome publications. They are reported in five-part code. Apart from giving the numerical value of the PCN, the report includes the pavement type (rigid or flexible) and the subgrade support strength category. Additionally, the report also allows the aerodrome authority to place a limit on the maximum allowable tire pressure if this is a constraint. Finally, it indicates whether the pavement was evaluated by technical means or based on past aircraft use of the pavement. A typical PCN published figure is PCN: 80/R, in which “PCN: 80” is the PCN value and “R” indicates rigid pavement. For flexible pavement, “F” is used. The pavement subgrade categories are A for high, B for medium, C for low, and D for ultralow subgrades. The maximum tire pressure authorized for the pavement is denoted by W = high, no limit; X = medium, limited to 217 psi; Y = low, limited to 145 psi; and Z = very low, limited to 73 psi. The pavement evaluation method is either T, indicating technical evaluation, or U, based on actual aircraft usage of the pavement. Pavement strength may also be expressed with the help of the load classification number (LCN).