The main goal of this research was to help users determine the proper timing of preventive maintenance by identifying how environmental aging affects asphalt material properties (binder and/or mixture) in the pavement and how the application of pavement preservation treatments impact the aging process. Two main test sections were studied: (1) a designed experiment on the Low Volume Road portion of MnROAD to look at aging through the application of treatments on an annual basis over a five-year period; and (2) a 10-year-old pavement on TH 56 in southern Minnesota, also a designed experiment, with seals applied on an annual basis over a four-year period. Mix testing on TH 56 cores indicated that subsections with chip seals applied more than two years after construction had essentially the same fracture energy properties as the unsealed control subsection - implying that the initial treatment from a preservation standpoint should occur within the first two years of the pavement's life to mitigate damage from environmental aging. The MnROAD sections did not show the same response. Based on the testing conducted during the study and the associated findings, it appears that rheological tests can be conducted on the asphalt binder recovered from a pavement core to assess the effects of oxidative aging. When possible, it appears prudent to use a mixture fracture energy test, such as the DC(T), in conjunction with asphalt binder rheological testing to quantify the effects of aging within a pavement and suggest appropriate timing for the application of preservation treatments.

"TRB's National Cooperative Highway Research Program (NCHRP) Report 523: Optimal Timing of Pavement Preventive Maintenance Treatment Applications describes a methodology for determining the optimal timing for the application of preventive maintenance treatments to flexible and rigid pavements. NCHRP Report 523 also presents the methodology in the form of a macro-driven Microsoft Excel Visual Basic Application--designated OPTime"--Publisher's description.

The proliferation of technological capability, miniaturization, and demand for aerial intelligence is pushing unmanned aerial systems (UAS) into the realm of a multi-billion dollar industry. This book surveys the UAS landscape from history to future applications. It discusses commercial applications, integration into the national airspace system (NAS), System function, operational procedures, safety concerns, and a host of other relevant topics. The book is dynamic and well-illustrated with separate sections for terminology and web- based resources for further information.

Highway agencies have constructed expansive networks of pavements that are vital to the economic prosperity and vitality of the nation. These networks are currently deteriorating at such a rate that most agencies cannot afford to reconstruct them in a timely manner. Consequently, many agencies have employed low-cost preventive maintenance (PM) techniques such as crack and surface treatments in an attempt to slow the deterioration rates of the pavements, thus extending the service life and delaying the time until reconstruction. This study sought to address whether or not recent advances in bituminous mixtures and binder selection through SuperPave necessitated a re-examination of current PM practices. In other words should SuperPave pavements be managed differently, compared to other mixture types in the network. The first project task sought to analyze the effectiveness of PM treatments by using historical pavement management data to develop pavement decay curves with time. The results of the analysis indicated a life extension; however due to data limitations, a life cycle cost analysis (LCCA) as well as a specific life extension value were not conclusively determined. The second project task assembled a pavement owner's manual to provide general guidance on applying PM treatments throughout a pavement's life. The recommendations of applying PM are based primarily on the pavement's age and general surface characteristics. The recommendations of task 2 are based upon experienced engineering judgment, empirical evidence and a literature review; consequently they must be tempered to the local conditions, environment and materials.