Browsing by Subject "Testing"
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Item Assessment of Stormwater Best Management Practices(University of Minnesota, 2008-04) Anderson, James L.; Asleson, Brooke C.; Baker, Lawrence A.; Erickson, Andrew J.; Gulliver, John S.; Hozalski, Raymond M.; Mohseni, Omid; Nieber, John L.; Riter, Trent; Weiss, Peter; Wilson, Bruce N.; Wilson, Matt A.; Gulliver, John S.; Anderson, James L.Item Center of Gravity Testing and Results(2014-07-24) Taylor, BrianItem Characterizing Phase-Center Motion of GNSS Antennas Used in High-Accuracy Positioning(Center for Transportation Studies, University of Minnesota, 2019-06) Dave, Aditya; Saborio, Ricardo; Sun, Kerry; Sainati, Robert; Gebre-Egziaher, Demoz; Franklin, RhondaEmerging transportation applications require positioning solutions with accuracy of a few centimeters. Current Global Navigation Satellite Systems (GNSS), such as GPS, GLONASS, and Galileo are, in some instances, capable of providing this level of accuracy. Real-Time Kinematic (RTK) techniques can generate solutions accurate to a few centimeters in a given locale. Precise Point Positioning (PPP) techniques promise to deliver RTK-level performance on a global scale. Even though low-cost, RTK-capable GNSS receivers are available today, antennas are a key component affecting quality of the positioning solution. Unless coupled with a high-quality (thus, more expensive) antenna, a low-cost receiver may not provide the centimeter-level accuracy needed for a safety-critical transportation application (e.g., autonomous vehicle, driver assist systems, etc.). Stability of the antenna phase-center is dependent on the antenna quality and can potentially move on the order of tens of mm if not centimeters. The purpose of the work reported here was to characterize the nature of this motion as a function of antenna quality. Anechoic chamber tests were performed using one high-cost and another low-cost GNSS antenna. The selected antennas represented “book ends” on the cost spectrum. These experiments showed that phase-center motion on the low-cost antenna can be a factor of four times larger than on high-quality antennas. Since anechoic chamber tests are not practical for each antenna installation in transportation applications, methods for antenna-specific, in-situ, phase-center motion calibration (modelling) methods have been suggested. Preliminary results suggested efficacy of these in-situ methods.Item A Comprehensive Evaluation of High Friction Overlay Systems on Bridge Decks in Cold Climate Regions(2015-05) Kostick, RobertIn recent history the Minnesota Department of Transportation has looked to improve the safety of bridge decks by installing high friction overlays (HFO). A comprehensive study researched four different proprietary HFO systems placed on fourteen bridge decks throughout Minnesota. Research was split into three separate tasks: (1) laboratory testing of aggregate properties, (2) field observations and testing, and (3) a comprehensive analysis of crash data investigated crash rates on bridges with HFO systems. Field observations and testing revealed that the use of snowplows quickly abrades HFO systems. Abrasion, among other factors, causes a reduction in surface friction values, and reduces the life of HFO systems. Furthermore, improving crash rate trends cannot be directly correlated to the installation of HFO systems. Research concludes that HFO systems should not be used in Minnesota. Other cold climate transportation agencies should conduct research emulated after this study to assess HFO systems in their jurisdiction.Item Critical thinking: assessing the relationship with academic achievement and demographic factors(2014-05) Vierra, Robyn WakaluaThe purpose of this study was to examine the relationship between critical thinking skills and academic performance, and to determine the degree to which demographic characteristics moderate the relationship. The California Critical Thinking Skills Test Middle School Series (CCTST-M series) was administered to assess critical thinking skill levels of students. Academic performance was measured by teacher assigned grades in core subject areas and the Measures of Academic Progress (MAP) test. The demographic factors - gender, tenure at Shanghai American School (SAS), and Culture (native language serving as a proxy for culture data) - were self reported and crosschecked with student records. Data was collected from 297 eighth grade students at Shanghai American School, a high performing American international school located in Shanghai, China. One-Way ANOVA and Stepwise models were used to examine the relationship between each of the factors and critical thinking. Results showed that grades and MAP test scores were significant predictor variables for critical thinking skills, indicating a strong relationship between critical thinking skills and academic achievement. Gender and tenure at SAS did not yield significant results, and do not moderate the relationship with critical thinking skills. Initial analysis also found culture to be an insignificant variable, except when math performance was factored out, Confucian students scored lower than non-Confucian students in critical thinking. This variance suggests a discipline specificity of critical thinking within some cultures, while also supporting the idea of culturally specific conceptualizations of critical thinking. Additional analysis also identified a relationship between academic achievement and gender and culture. Females receive higher grades and score higher in the language usage portion of the MAP test. In the mathematics portion of the MAP test, males score higher than females and Confucian students score higher than non-Confucian students. Results indicate that academic achievement is closely tied with critical thinking and that some variation exists across cultures. Additional research is suggested to further study why these variations, along with differences in academic achievement, exist.Item Developing Salt-Tolerant Sod Mixtures for Use as Roadside Turf in Minnesota(Center for Transportation Studies University of Minnesota, 2014-12) Friell, Joshua; Watkins, Eric; Horgan, BrianFailure of roadside grass installations due to high levels of road salt is a common occurrence in Minnesota. Several species that are not currently included in the MnDOT recommendations for these sites have performed well in low-input turfgrass evaluations in Minnesota and warranted evaluation for salt tolerance and suitability for roadside environments. The goal of this project was to develop a recommended mixture or a set of mixtures that provide salt-tolerant sod for roadsides. In the first part of this research, cultivars of cool-season turfgrass were assessed for their ability to establish and survive on roadsides in Minnesota. Concurrently, these grasses were evaluated in a hydroponic system in the greenhouse for salinity tolerance. Together, these studies identified several species and cultivars that were promising for use on Minnesota roadsides. These top-performing grasses were then evaluated in a series of mixtures in three research trials: (1) a roadside evaluation at two locations in Minnesota; (2) a sod strength trial planted at two locations in Minnesota; and (3) an acute drought evaluation utilizing an automated rainout shelter. From these results, we identified species that should be components of a salt-tolerant turfgrass mixture for use on roadsides in Minnesota. Mixtures that included high proportions of fine fescues, especially hard fescue and slender creeping red fescue, performed the best in our trials indicating that these species should be utilized in MnDOT recommendations for turf grown on roadsides.Item Making sense of testing: English language learners and statewide assessment(2008-07) Stone, Karla RaeThe federal No Child Left Behind (NCLB) Act of 2001 has dramatically changed the educational landscape for all students by increasing the number of standardized tests used for accountability purposes. The impact is profound on students for whom English is not their first language, in part because of the sheer number of tests they are required to take. The challenges increase when tests become high stakes for students in the form of high school exit exams, an increasingly prevalent requirement in states, though not required under NCLB. The policies for tests are complex and can easily be viewed as devoid of any attention to the human side of testing--the ground level, nuanced, and sometimes complicated application of policy at the student level. Yet it is at this level where a policy becomes truly validated. The literature on accountability testing rarely considers student perceptions. This research is an attempt to contribute to that void by combining a student voice paradigm with a sense-making framework. Case study methodology was used and incorporated methods that moved from breadth towards depth as the study evolved. In the case of this research, that evolution was from participant observation (Phase I) to document review, inquiry groups and interviews (Phase II). Participants' pre-existing knowledge and experiences with testing are explored alongside the new knowledge gained as participants in this research study. Findings clearly demonstrate that the stakes connected to testing influence the ways in which students make sense of testing, as do the policy signals. Beyond contributing to the fields of educational policy and student voice initiatives, the intent of this research is to spur advocacy on behalf of and in conjunction with English language learners. Whether for systems accountability (the Test of Emerging Academic English), or for individual accountability as a requirement for a diploma in Minnesota (the Basic Skills Tests), the findings reveal both the complexities of and urgency for exploring testing policies from students points of view. Additionally, findings validate the need for students' voices in policy research, and suggest several implications based on reported experiences with statewide testing.Item Minnesota Crash Records Audit(Center for Transportation Studies, University of Minnesota, 2020-08) Morris, Nichole L.; Libby, David A.; Peterson, Colleen; Ryan, Andrew; Sheppard, McKenzieIn 2016, Minnesota deployed a state-of-the-art electronic crash reporting system to all law enforcement officers across the state. The updated crash report was created with the officer in mind through an extensive usability and design project led by HumanFIRST. Preliminary testing of the new system suggested high user satisfaction but could not determine the extent of the crash data improvement. This study employed a mixed-methods approach to conduct a series of qualitative analyses of the crash data records collected by the legacy crash reporting system and the new MNCrash reporting system. The first analysis compared 360 serious injury and fatal crash reports from 2015 and 2016 and found a year-to-year decrease in mismatching data but a slight increase in missing data. However, overall, the MNCrash system increased the number of data queries, so data access was increased in 2016. The second analysis of serious and fatal injury crashes compared 996 reports sampled from 2015 and 1,572 reports sampled from 2016. The analysis showed a decrease in missing data and a decrease in erroneous data entry in 2016. Finally, the converted 2015 legacy data was analyzed to reveal few errors in the MNCrash conversion process.Item Statistical Methods for Materials Testing(Minnesota Department of Transportation, 2009-12) Gupta, Diwakar; Peterson, AmyMn/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.