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This report summarizes the final results of the enhancement and validation of the control-emulation method in the real freeway environment. A computer-based control-emulation method that can evaluate various automatic rate-selection strategies was developed by this research team in the previous phase of this research. Software was developed that operationalizes this method for field applications. A method was developed and tested to determine the best metering thresholds for a given section of a freeway, under normal weather conditions, using the control-emulation method and the downhill simplex optimization procedure. The method finds the optimal thresholds for each ramp in a given. section of the freeway by considering the system-wide traffic conditions. An independent procedure to determine the initial thresholds that can be used to initialize the optimization process was also developed. A preliminary study for developing an on-line predictor for freeway exit demand was performed and an adaptive prediction procedure was developed. The prediction model formulated in this research used historical demand and current day measurements. Further, the parameters in the prediction model are updated in real time using the Extended Kalman Filter, so that the propagation of prediction error can be minimized.

Coating reinforcing bars with epoxy was assumed to be the answer to corrosion problems in highway structures when it was developed. In the last few years, this assumption has been seriously questioned. Cases of damage to structures resulting form corrosion of epoxy coated steel have been reported in Florida, New York and Ontario. In 1992, the Physical Research Section was asked by the Office of Bridges and Structures at the Minnesota Department of Transportation to conduct a limited field survey to determine if a problem existed in Minnesota. The first bridge built with epoxy coated rebars in Minnesota shows no signs of distress almost 20 years after construction. The corrosion of epoxy coated rebars that has been observed elsewhere was not discovered by this survey. The prestressed girder bridges included in this survey· showed fewer transverse cracks than the steel girder bridges.

This Technical Summary pertains to LRRB’s Research Implementation Committee’s product 2008RIC04, “Training Module for Pavement Rehabilitation Selection,” delivered June 2008. The central reports used to develop this training course were LRRB-produced Reports 2008-06, “Pavement Rehabilitation Selection,” published January 2008, and 2006-31, “State Aid Concrete Pavement Rehabilitation Best Practices Manual 2006,” published September 2006.

This Research Summary accompanies Report 2024-05, "Traffic Safety Evaluation at J-turns in Minnesota," published February 2024.

Base stabilization additives are used to increase the strength and stiffness of road foundations on weak and susceptible soils. The Minnesota Department of Transportation (MnDOT) quantifies the structural contribution of pavement layers by introducing granular equivalency (GE) factors. While numerous additives exist for improving the performance of aggregate base layers, this study focuses on proprietary additives including Base One, Claycrete, EMC SQUARED, PennzSuppress and Roadbond EN1. The laboratory study revealed that EMC SQUARED was the superior stabilizer, with an optimum dosage set 15% higher than the manufacturer recommended dosage (MRD). The long-term performance of proprietary additives was monitored by considering full-scale field implementation with optimum additive dosages obtained from laboratory investigation. Controlled sections without stabilization exhibited higher values in the California Bearing Ratio (CBR) and composite elastic modulus right after construction, while the impact of stabilizers on the increasing strength of the full depth reclaimed (FDR) base was revealed after two years of construction. Falling-Weight Deflectometer (FWD) tests demonstrated a progressive increase in the stiffness of stabilized sections over time, surpassing the control section's stiffness after two years. The economic analysis utilizing Life Cycle Cost Analysis (LCCA) indicated that stabilized sections, particularly those treated with EMC SQUARED, offered lower Equivalent Uniform Annual Cost (EUAC) values across various maintenance scenarios. These findings suggested potential cost savings over a pavement's life cycle with higher GE factors of recycled asphalt pavement base aggregate treated with proprietary additives. The findings will contribute to a comprehensive understanding of the benefits, feasibility, and design considerations associated with using commercial stabilizers in FDR base layers.

This Research Summary is part of Report 2024-08, "Effect of Increased Precipitation (Heavy Rain Events) on Minnesota Pavement Foundations," published April 2024.

The recent legalization of recreational marijuana use in Minnesota prompted MnDOT’s Office of Traffic Engineering to request this Transportation Research Synthesis (TRS) to gather information about the impacts to traffic safety of such legislation in other states. Using a survey of the states and district where recreational use of marijuana has been legal for some time or only recently legalized, this TRS examines any changes in traffic safety; the effects law enforcement agencies have identified after legalization; and the guidelines, procedures and experts law enforcement use to determine impairment of recreational marijuana users. Findings from this TRS are expected to inform future actions by MnDOT and local agency staff, as well as the state and local policymakers and legislators seeking to assess the traffic safety impacts associated with legalizing recreational marijuana use.

The Minnesota Department of Transportation (MnDOT) Office of Livability established the Livability Framework to guide transportation policies, programs, and/or projects toward improved, people-focused outcomes. The Livability Framework proposes seven (7) Livability Pillars to be considered as part of the planning and implementation of these activities. These Livability Pillars include Health and Environment, Economic Vitality, Sense of Place, Safety, Connectivity, Equity, and Trust. To support this effort, a Livability Measurement Tool (or tools) will be developed to help planning agencies measure, represent, interpret, evaluate, and track livability considerations, and, thereafter, determine appropriate action to address identified needs. An initial step for this work is a summary identification of current best practices for measuring livability. This report provides a literature analysis of research conducted on measuring livability and identifies points of consensus, debates, and gaps in the research on the measurement of livability as the MnDOT Office of Livability defines the concept. Within the body of research analyzed, there was consensus regarding the effect of the built environment on human health and subjective well-being, and measurements for its assessment. However, there are notable gaps in existing literature for measuring feelings of belonging, the inequitable burden of transportation systems on vulnerable populations, and distrust in government by residents, among other issues.

This Appendix relates to Transportation Synthesis Report 2401, Measuring the Livability Framework, published February 2024.

This appendix is part of project 2001-16, "Condition and Durability of Segmental Concrete Block Retaining Walls Along Roadways in Minnesota."