Abstract
Aircraft pavements are generally strength rated through the Aircraft Classification Number—Pavement Classification Number (ACN-PCN) system, or the newer Aircraft Classification Rating—Pavement Classification Rating (ACR-PCR) system. Overload operations occur when an aircraft ACN is greater than the PCN of a pavement, and in these cases, pavement concessions are granted based on an allowable ratio of ACN to PCN. The equivalent pavement structural damage for a single operation of a given ACN-PCN ratio is well understood, with airport authorities usually allowing a maximum overload concession based on a maximum ACN-PCN overload ratio. However, the recommended frequency of overload operations is based on a somewhat arbitrary set of rules, with different airport authorities applying different frequency limits. This research analysed the effect of overload operations on the theoretical pavement life of a network of Australian military and civilian airfields when using an existing pavement concession system. It was determined that the effect of the pavement concession system on theoretical pavement life was highly dependent on the initial design traffic inputs. A new overload concession system was then developed that considers the inherent conservatism in aircraft pavement design and construction and allocates that conservatism to a lifetime overload allowance. Although this research and the proposed concession system were performed using the ACN-PCN system and in the Australian context, it can also be adapted for overseas airports and for use with the newer ACR-PCR system.