In March of 1998, the Federal Aviation Administration issued revisions to P-501 "Portland Cement Concrete Pavement" and P-110 "Methods of Estimating Percentage of Material Within Specification Limits." The specification revisions affect the statistical acceptance criteria for strength and thickness. Paving contractors should take particular note of the payment section of the new P-501 specification, which has been substantially revised. This article details the principal changes and how they differ from the previous requirements. Also included is a reprint of the payment section, along with a table showing the new price adjustment schedule.