Browsing by Subject "Field tests"

Now showing 1 - 6 of 6
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    Cost/Benefit Analysis of the Effectiveness of Crack Sealing Techniques
    (Minnesota Department of Transportation., 2019-06) Barman, Manik; Munch, Jared; Arepalli, Uma M
    Crack sealing is an important preventive treatment in the pavement preservation program. To achieve a cost-effective crack seal, it is important to select a proper crack sealing method. While Minnesota usually seals cracks in asphalt pavements, there is no clear consensus on the most appropriate crack sealing method for a specific job. This study focused on developing a guideline so that a cost-effective crack sealing method could be chosen based on pavement type, functional condition, pavement age, and traffic volume etc. This study includes a literature review, online survey, field performance data collection and analysis, and development of a guideline. The effectiveness of the crack seals was determined using a benefit-cost analysis. Two decision trees were developed for choosing the most appropriate crack sealing method. The first, which can be used in MnDOT’s pavement management system, needs information such as crack severity, pavement type (new vs overlay), pavement analysis period and design life, traffic level, and crack seal occurrence number. The second decision tree, which is a simplified version of the first and can be used by the preventive maintenance crews and requires less information: crack severity, traffic level, and crack sealing occurrence number.
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    Field Implementation of Direction Rumble Strips for Deterring Wrong-Way Entries
    (Center for Transportation Studies, University of Minnesota, 2019-07) Zhou, Huaguo; Xue, Chennan
    This report presents the field implementation results of three directional rumble strip (DRS) patterns designed to deter wrong-way (WW) freeway entries. Southbound off-ramps at Exits 208 and 284 on I-65 in Alabama were selected for implementation because they were ranked as high-risk locations by a network screening tool developed by Auburn University. Three patterns (D3, C, and E.1) were recommended for field implementation based on the results of a previous project. Pattern D3 was installed at the off-ramp terminal near the stop bar or yield line. Pattern C was implemented at the segment between the terminal and ramp curve. Pattern E.1 was placed on the tangent part before the ramp curve. WW incident and traffic speed data before and after the implementation were collected using cameras and magnetic sensors, respectively. Field driving tests were conducted to collect sound and vibration data at various speed categories for both RW and WW directions. Before and after studies evaluated the effectiveness of the DRS patterns in reducing wrong way driving (WWD) incidents and traffic speeds on off-ramps. Sound and vibration analyses quantified the differences between right way (RW) and WW drivers’ perceptions. Results showed that the number of WWD incidents and average driving distances were significantly reduced after implementing all of the DRS. The results confirmed that WWDs can perceive elevated sound and vibrations when passing the DRS. The DRS can also reduce the 85th percentile, mean, and standard deviations of off-ramp traffic speeds. A general guideline was developed for implementing different DRS to deter WW freeway entries.
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    Full-Depth Reclamation (FDR) for Suburban/Urban and Local Roads Application
    (Minnesota Department of Transportation, 2016-12) Hartman, Marcella; Turos, Mugur; Ghosh, Debaroti; Marasteanu, Mihai
    Full-depth reclamation (FDR) as a rehabilitation method improves the service life of pavement structures by reusing asphalt materials, thereby reducing costs and allowing for conservation of nonrenewable resources. However, the lack of mechanicsbased material testing procedures and performance-based specifications limit the use of FDR processes. First, the FDR design and construction process are presented, then, a literature review focusing on FDR research is completed, and a survey is conducted to obtain relevant information regarding current FDR practices in Minnesota. Next, Indirect Tensile Test (IDT) and Dynamic Modulus Test in IDT mode testing is performed on four FDR materials: Field mixed, Lab compacted; Lab mixed, Lab compacted; FDR with cement additive; and FDR with graphene nanoplatelet (GNP) additive. Two curing times are used to determine how physical properties change over time. Test results are used to perform simulations in MnPAVE software and a Life Cycle Cost Analysis (LCCA). Laboratory observations indicate that cement additive reduces predicted life and increases critical cracking temperature with a slight increase in cost; GNP additive reduces predicted life but also reduces critical cracking temperature with a significant cost increase; Lab mixed samples performed better than Field mixed, suggesting that field methods could be improved; and curing has a positive effect on the FDR materials with cement and GNP additives--for both materials, the dynamic modulus increase, and the GNP samples also had a slight increase in tensile strength. MnPAVE simulations and LCCA results indicate that over a 35-year period, FDR may be a more cost-effective method than traditional mill and overlay.
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    Older Driver Support System (ODSS) Usability and Design Investigation
    (Center for Transportation Studies, University of Minnesota, 2018-01) Morris, Nichole L.; Craig, Curtis M.; Libby, David A.; Cooper, Jennifer
    Older drivers represent a high-risk population on the road, due to age-related declines in cognition and perception. The present research investigated whether an Older Driver Support System (ODSS) smartphone application would be useful. The research presented here was comprised of (1) focus groups, surveys, and interviews, (2) simulated driving with video playback, and (3) on-the-road field-testing. The methodology centered on iterative re-design of the ODSS interface based on feedback and behavior of older drivers. This iterative re-design approach was successful at making the ODSS interface more usable when considering System Usability Scale (SUS) scores. Furthermore, older drivers during the field test reported minimal mental effort expended when using the smartphone application and many significantly positive statements about the application. The field test resulted in several final recommendations for the ODSS application. A promising final takeaway was a universal design approach preferred by the older drivers, as they did not want to be singled out for special attention.
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    Older Driver Support System Field Operational Test
    (Center for Transportation Studies, University of Minnesota, 2019-05) Libby, David A.; Morris, Nichole L.; Craig, Curtis M.
    Older drivers represent the highest injury and fatality rate per 100 million miles driven. The disproportionate fatality risk is linked to several known factors, ranging from failure to yield to cognitive and visual limitations to seatbelt use abstention to fragility. Through a series of focus groups, usability tests, and a controlled field test, a universally designed smartphone app (called RoadCoach) designed to reduce risky driving behaviors, such as speeding and hard braking, was previously found to have high usability among older drivers. The current research consisted of a field operational test of the app, which examined the baseline driving behavior (3 weeks) of 28 older drivers in Minnesota and Kansas, their driving behavior with RoadCoach feedback (6 weeks), and their driving behavior during a follow-up, no-feedback period (3 weeks). The results demonstrated marginal reductions in speeding behaviors while the app was functioning, but speed behaviors significantly increased after the feedback was discontinued compared to when it was active. Hard braking and stop sign violations were significantly reduced during feedback and post feedback. Finally, satisfaction and trust were high among users, with drivers reporting that the app helped improve their attention and focus on the task of driving.
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    Statistical Methods for Materials Testing
    (Minnesota Department of Transportation, 2009-12) Gupta, Diwakar; Peterson, Amy
    Mn/DOT provides incentives to contractors who achieve high relative density via a pay factor applied to each unit of work. To determine the pay factor, Mn/DOT divides each day of a contractor’s work into a small number of lots. Then, core samples are taken from two locations within each lot and the relative densities of the cores are calculated by performing standardized tests in materials testing laboratories. The average of these two values is used as an estimate of the lot's relative density, which determines the pay factor. This research develops two Bayesian procedures (encapsulated in computer programs) for determining the required number of samples that should be tested based on user-specified reliability metrices. The first procedure works in an offline environment where the number of tests must be known before any samples are obtained. The second procedure works in the field where the decision to continue testing is made after knowing the result of each test. The report also provides guidelines for estimating key parameters needed to implement our protocol. A comparison of the current and proposed sampling procedures showed that the recommended procedure resulted in more accurate pay factor calculations. Specifically, in an example based on historical data, the accuracy increased from 47.0% to 70.6%, where accuracy is measured by the proportion of times that the correct pay factor is identified. In monetary terms, this amounted to a change from average over and under payment of $109.60 and $287.33 per lot, to $44.50 and $90.74 per lot, respectively.