series within Research Reports collection

Investigation of In-Place Asphalt Film Thickness and Performance of Minnesota Hot Mix Asphalt Mixtures

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Date Created
2009-06
Report Number
P2009-01
Description
Two methods for calculating the aggregate surface areas, the Surface Area Factor and Index methods, are discussed in this research and the results are further used to compute an average asphalt film thickness in asphalt mixtures. Field performance data from six Minnesota routes and MnROAD, including both coarse and fine gradations, were analyzed to determine significant correlations between asphalt film thickness values and the performance of asphalt mixtures. The analysis showed that the asphalt film thickness is a significant factor affecting the rutting performance for asphalt mixtures. However, the pavement performance is also affected by many other factors such as traffic level and surrounding environment. More research work is needed to investigate the relationship between the asphalt film thickness and the other performance parameters of asphalt mixtures such as fatigue cracking.

Traffic Flow Modeling, Simulation, and Signal Timing Plans Evaluation of the Miller Hill Corridor

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Date Created
2002-12
Report Number
P2003-02
Description
Traffic flow study of the Miller Hill corridor on Highway 194 between Arlington Avenue and Haines Road, the most heavily traveled and congested roadway in the Duluth area. The study includes preliminary data collection using a non-intrusive Remote Traffic Microwave Sensor (RTMS), traffic flow modeling, traffic simulation and development of an efficient traffic signa l light timing plan. The author develops a reasonably accurate model to estimate traffic flow, which is used in association with the RTMS and a database system to conduct real-time traffic simulations. Results of the simulation were used to develop a traffic-signal optimization plan with Synchro 5.0 software. Discussion of problems faced and how improvements could be made through further research. The author concludes with a proposal that recommends the adoption of the newly developed signal-timing plan to alleviate the traffic congestion on the Miller Hill corridor.

Production and Characterization of Mycorrhizal Fungal Inoculum

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Date Created
2004-07
Report Number
P2004-01
Description
The aim of this research is to produce a local, diverse mycorrhizal inoculum for commercial production for use in the Minneapolis/St. Paul area. In earlier studies, spores of several arbuscular mycorrhizal fungal (AMF) species were isolated from a Minnesota remnant prairie and identified by morphological features. For each species, single spore cultures were established and stored in the cold for 6 to 7 years. Objectives of this project were to produce pot cultures from the single spore cultures and to recommend AMF species for commercial production. To check the identity of the fungi before and after inoculum production, genetic identification of fungi used to develop the inoculum should be performed. The extraction and preservation of DNA of AMF species were done. DNA analysis showed general agreement between the morphological and molecular identification of the spores and their placement in genera. However, results suggested that some species placement might not be consistent where these comparisons can be made. Further research may result in the re-naming of some species. Several AMF species are recommended as candidates for commercial inoculum production based on production of spores in pot cultures, on their longevity in cold storage, and in some species on molecular traits.

Traffic Safety Evaluation of Lane Constrictor Intersections in Minnesota

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Date Created
2024-02
Report Number
2024-03
Description
Between 2018 and 2019, MnDOT installed a lane constrictor design at 66 side-street, stop-controlled intersections in Minnesota. The lane constrictor design narrows the lane width for mainline approaches via a striped median with centerline rumble strips. By narrowing the mainline lane, the goal of this design is to encourage mainline traffic to slow down as it approaches the intersection. The striped median also provides greater separation between mainline directions and draws more attention to the location of the intersection. Following the installation of lane constrictors at MnDOT intersections, overall crash rates have seen little change but there have been decreases in fatal and serious injury (KA) as well as fatal and all injury (KABC) crash rates. These results indicate the addition of lane constrictors have a positive impact on crashes by reducing the severity of crashes, swapping injury crashes for property damage only crashes.

Traffic Safety Evaluation of Signalized Intersections with Retroreflective Backplates in Minnesota

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Date Created
2024-01
Report Number
2024-04
Description
Between 2016 and 2021, MnDOT installed retroreflective signal backplate borders at 116 signalized intersections in Minnesota. Retroreflective signal backplate borders are intended to further increase visibility of the signal head both during the day and at night. The goal of installing retroreflectivity to backplates is to reduce crashes at the intersection by drawing more attention to the current phase of the signal. Backplates with retroreflective borders are listed as a Federal Highway Administration Proven Safety Countermeasure with a listed safety benefit of a 15% reduction in total crashes. With the installation of retroreflective signal backplates on MnDOT signals, the changes in crash rates were not found to be statistically significantly different from similar locations that did not have retroreflective signal backplates. These results indicate there has been little impact on crash rates in the few years after the installation of retroreflective signal backplates.

Development of a Mobile App for Reporting Work Zone Intrusions

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Date Created
2024-01
Report Number
2023-04
Description
Work zone intrusions represent a significant safety risk to workers. To help better understand these situations, the Minnesota Department of Transportation partnered with the University of Minnesota to create a method to document intrusion events. This information provides a deeper understanding of the circumstances under which these events occur and enables data-driven decision making when considering ways to reduce or mitigate work zone intrusions. This work focuses on the development of a mobile smartphone app that allows workers to report intrusions from the field immediately after they occur, allowing for timely and accurate intrusion reporting. The work zone intrusion mobile app is developed using an iterative, user-centered design process that solicits feedback from work zone personnel, supervisors, and work zone safety stakeholders at every step in the process. The app uploads completed report data to the existing eSAFE system, allowing for a single repository of collected intrusion report data. To support deployment of the system, training workshops and supporting training and communications materials are created for distribution among users. Throughout the development and deployment of the app, user feedback shows that the app is easy to use and well liked.