Theses and Dissertations at Montana State University (MSU)
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Item Feasibility study for field-scale use of Ureolysis-Induced Calcite Precipitation (UICP) for roadbed improvement(Montana State University - Bozeman, College of Engineering, 2023) Dorian, Hudson Thomas; Chairperson, Graduate Committee: Mohammad Khosravi; Adrienne J. Phillips (co-chair); This is a manuscript style paper that includes co-authored chapters.A series of tests were conducted to evaluate the feasibility of using ureolysis-induced calcium carbonate precipitation (UICP) to improve the strength of the soil layers used to in the construction of roads. This process involved three series of tests conducted on soil specimens of gradually increasing volume. The first series regarded the relative effect of treatment direction, comparing top-down treatment to bottom-upwards and alternating treatment methods on 50-by-100-millimeter soil columns. This was evaluated through unconfined compressive strength (UCS) and the calcium carbonate distribution over the length of the soil, finding that all methods generated a reliable increase in the strength of the soil specimen. This phase of research also included a batch study, evaluating the growth of the ureolytic bacteria Sporosarcina pasteurii in a solution composed of commercially available ingredients, showing that the bacteria could be cultured at a far lower cost (as low as 20 cents per liter) than with lab-grade ingredients ($2.66 per liter). The next series of tests compared the effect of applying treatment solutions to the soil surface directly and using a probe to inject solutions beneath the surface. This was done with 15-centimeter, cylindrical specimens, evaluated through the California bearing ratio (CBR) test. It was determined that the treatment process had the capacity to increase the CBR value substantially (from ~11% up to 188%), and it was suggested that each treatment mechanism resulted in a predictable distribution of calcium carbonate. There was also success in using alternative, commercially-sourced ingredients to facilitate the treatment and improve the CBR value. The last tests centered on the treatment of a 30-centimeter-by-30-centimeter mock road section, combining the treatment mechanisms used at the 15-centimeter-scale to facilitate an increase in the CBR of a soil layer under pavement. Through UICP, the CBR value of this layer was successfully increased.Item The evaluation of modern roundabouts as an alternative to signalized and two-way stop controlled intersections in a urban and rural environment(Montana State University - Bozeman, College of Engineering, 2004) Eickman, Travis John; Chairperson, Graduate Committee: Jodi L. CarsonThe comparison of roundabouts with other intersection forms of traffic control is becoming an increasingly common occurrence. With little overall experience within the United States, the data for roundabout comparison is somewhat varied. This report includes the results of five models created using VISSIM traffic modeling software in the comparison of a two-way stop, signal and roundabout in an urban environment, and a two-way stop and roundabout in a rural environment. A large amount of field data in the form of traffic volumes, vehicle types, gap timing and headway distances were used in the calibration and validation of the various models. Multiple runs of the models were conducted to attain an expansive data pool from which to evaluate the different modes of traffic control. Measures of effectiveness included crash reduction, delay, and queue length. Due that crash data could only be obtained for the before period of the base case studies, a detailed crash reduction analysis could not be conducted. A limited analysis was conducted to review the possible reduction in the possibility of accidents and their severity. Delay values indicated the roundabout provided the best performance, followed by the signal, and lastly the two-way stop. Average queue length data indicated that the roundabouts functioned with no notable queuing experienced. The results of the signal indicated improved performance on that of the two-way stop. The results indicate that roundabouts are a viable alternative to a two-way stop and signal. For a more accurate, long-term evaluation, growth projections should be applied to existing conditions to determine the operational effectiveness of the intersection traffic control type at some point in the future. Depending on the purpose and need of any intersection being evaluated, additional focus can also be concentrated on obtaining additional field information for driver behavior, gap timing, headway distances, delay times and average queue lengths.Item Traffic performance on two-lane, two-way highways : examination of new analytical approaches(Montana State University - Bozeman, College of Engineering, 2006) Durbin, Casey Thomas; Chairperson, Graduate Committee: Ahmed Al-KaisyThis project presents research on estimating traffic performance on two-lane, twoway highways. The main research objective is to examine two new approaches / methodologies in estimating the Percent-Time-Spent-Following (PTSF), a major indicator of performance on two-lane highways. The first new approach, named the weighted-average approach, is based on the weighted average of speeds for various vehicle types within the traffic stream. The second new approach, named the probabilistic approach, is concerned with using probabilities in estimating the PTSF. The need for this investigation has arisen from the concern that the current analytical procedures, namely the Highway Capacity Manual (HCM) 2000, provide erroneous results as suggested by previous research. The project reviews recent literature on the HCM procedures and evaluates their effectiveness using both theoretical and empirical analyses. Furthermore, the two new approaches were evaluated using empirical data from three study sites located throughout Montana's two-lane, two-way highway system.Item Channelized right-turning lanes at signalized intersections : a review of practice and an empirical study(Montana State University - Bozeman, College of Engineering, 2011) Roefaro, Sommer Ann; Chairperson, Graduate Committee: Ahmed Al-Kaisy; Patrick McGowen (co-chair)This research includes a review of the current literature and practice regarding channelized lanes for right turns and the selection of an appropriate traffic control device. The main goal is to gain a better understanding of channelized right-turning lane guidelines used in practice and the effectiveness of a signal control device to regulate access at the channelization. This thesis presents a literature review and survey investigation into the current practice, the type of traffic control used, and the safety experience of highway agencies. Additionally an empirical study was conducted to examine the driver behavior at channelized right-turn lanes using raised (curbed) islands, where an exclusive signal control is used for the channelized traffic movement. The literature review revealed an overall lack of knowledge concerning the operational and safety aspects of channelized right turn lanes, especially concerning the type of traffic control used. This may explain, to a large extent, the lack of guidance in practice and the broad range of behaviors demonstrated by drivers during the field investigation. The survey results suggest a heavy reliance on engineering judgment by highway agencies in the use of channelized right-turn lanes and the selection of traffic control. Further, results confirmed a general perception in practice about the safety benefits of signal control at channelized right-turn lanes, despite the fact that such benefits were not supported in the literature. Three study sites in the cities of Belgrade and Bozeman in southwest Montana were investigated for the empirical study with approximately seven days of data for the analysis. The three study sites used a signal as the control for the channelization. The results of the investigation showed that over half of the drivers using the channelized turn lane treated the traffic signal as a yield control, while only a very small percentage of drivers treated the situation as a signal control. Further, statistical analyses confirmed that drivers' treatment of control is influenced by light conditions, vehicle type and traffic volume. This research emphasizes the need for further research into the safety and operational aspects of this right-turn treatment at intersections, particularly the type of control used for the channelization.