Benefits, Limitations and Potential Improvements of ACR-PCR for Airport Pavement Strength Rating

Abstract: The original airport pavement strength rating system, known as Aircraft Classification Number-Pavement Classification Number (ACN-PCN), has been in place since 1981. A new system, known as Aircraft Classification Rating-Pavement Classification Rating (ACR-PCR), was announced in 2020 and was implemented in November 2024. However, some countries have delayed its implementation until 2025 or even 2026. The two systems are similar in their operational form and function, but the mathematics used to determine aircraft wheel interaction at subgrade depth within pavements, and the relative damage caused by different aircraft, are substantially difference. The main difference is the transition from the simple mathematics that was necessary in the late 1970s when ACN-PCN was developed, to layered elastic analysis and other processes associated with contemporary airport pavement thickness determination. This research reviews the two systems and discusses the benefits, limitation and some potential improvements to the new system. Some system benefits include the standardisation of subgrade categories for rigid and flexible pavements, more representative standard pavement structures and the use of Miner's Law for the combination of damage caused by different aircraft. Some limitations include the change in the flexible pavement subgrade category limits and representative values, the improvement of the surface protection to more than simply the tyre inflation pressure, and the provision of a rational PCR determination option when the standard calculation method is not strictly followed, but a design-based assessment is still made.. This paper aims to inform airport pavement managers and designers of the pros and cons associated with the transition from ACN-PCN to ACR-PCR, as well as to recommend potential future improvements to ACR-PCR to the International Civil Aviation Organisation responsible for its development.