Scholarly Work - Civil Engineering
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/3460
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Item Kinetics of Calcite Precipitation by Ureolytic Bacteria under Aerobic and Anaerobic Conditions(2019-05) Mitchell, Andrew C.; Espinosa-Ortiz, Erika J.; Parks, Stacy L.; Phillips, Adrienne J.; Cunningham, Alfred B.; Gerlach, RobinThe kinetics of urea hydrolysis (ureolysis) and induced calcium carbonate (CaCO3) precipitation for engineering use in the subsurface was investigated under aerobic conditions using Sporosarcina pasteurii (ATCC strain 11859) as well as Bacillus sphaericus strains 21776 and 21787. All bacterial strains showed ureolytic activity inducing CaCO3 precipitation aerobically. Rate constants not normalized to biomass demonstrated slightly higher-rate coefficients for both ureolysis (kurea) and CaCO3 precipitation (kprecip) for B. sphaericus 21776 (kurea=0.10±0.03 h−1, kprecip=0.60±0.34 h−1) compared to S. pasteurii (kurea=0.07±0.02 h−1, kprecip=0.25±0.02 h−1), though these differences were not statistically significantly different. B. sphaericus 21787 showed little ureolytic activity but was still capable of inducing some CaCO3 precipitation. Cell growth appeared to be inhibited during the period of CaCO3 precipitation. Transmission electron microscopy (TEM) images suggest this is due to the encasement of cells and was reflected in lower kurea values observed in the presence of dissolved Ca. However, biomass regrowth could be observed after CaCO3 precipitation ceased, which suggests that ureolysis-induced CaCO3 precipitation is not necessarily lethal for the entire population. The kinetics of ureolysis and CaCO3 precipitation with S. pasteurii was further analyzed under anaerobic conditions. Rate coefficients obtained in anaerobic environments were comparable to those under aerobic conditions; however, no cell growth was observed under anaerobic conditions with NO−3, SO2−4 or Fe3+ as potential terminal electron acceptors. These data suggest that the initial rates of ureolysis and ureolysis-induced CaCO3 precipitation are not significantly affected by the absence of oxygen but that long-term ureolytic activity might require the addition of suitable electron acceptors. Variations in the ureolytic capabilities and associated rates of CaCO3 precipitation between strains must be fully considered in subsurface engineering strategies that utilize microbial amendments.Item Perceived Risk of Phoning While Driving: A Case Study from Jordan(2015-10) Ismeik, Muhannad; Al-Kaisy, Ahmed; Al-Ansari, KhalidThe use of mobile phones while driving is banned in most countries since it impairs driving performance and is believed to increase crash risk. The aim of this research is to identify the prevalence of phoning while driving in Jordan and to examine the association between drivers’ perception of risk and potential predicting variables. A sample of 423 drivers was surveyed to gather information on their mobile phone use while driving as well as their risk perception. Data collection took place anonymously at diverse locations through a self-report questionnaire. Statistical analysis was performed to highlight the association between risk levels and drivers’ demographics and exposure characteristics. An alarming rate of 93.1% of drivers, mostly young male college students, engaged in this unsafe behavior despite being aware of the associated risk and legislative laws. Findings suggested gender, employment status, age, education level, driving experience, and daily traveled distance were associated with mobile phone use while driving. Recommendations to enhance traffic safety were proposed and further research directions were highlighted.Item Traffic Safety Along Tourist Routes in Rural Areas(2016-01) Wang, Yiyi; Veneziano, David; Russell, Sam; Al-Kaisy, AhmedLittle is known about the safety of tourist drivers in the United States. Most domestic studies have focused on traffic deaths and injuries of U.S. citizens traveling abroad and cite factors such as driving on the left, lack of seat belt use, and alcohol consumption. U.S. states that have a number of tourist attractions and the roadways to reach them may be interested in whether traffic safety is problematic for drivers who are tourists. To that end, this research investigated the contributing factors for crash severity and crash likelihood of visiting drivers in or near three national parks in rural areas. Driver-level data from the Rocky Mountain National Park in Colorado and the Sequoia and Kings Canyon National Parks in California revealed risk factors for crash severity, including age, geometry, and seat belt use. The second data set offered a more microscopic view at the road level and was used to anticipate crash frequency of visiting drivers at the road link level. Moreover, the second data set contained road geometry, traffic volume, environment, and crash counts aggregated at the segment level along a 57.8-mi stretch of U.S. Hwy 89 (a primary route to the north gate of Yellowstone National Park) in Montana that is frequently used by tourists. Crash risk factors (e.g., geometry and traffic intensity) affected local and nonlocal (tourist) drivers in different ways. Further exploration of crash trends in specific parks would be valuable in understanding the overall trends and contributors to crashes in tourism areas and to determine effective improvement measures.Item Safety Effects of Road Geometry and Roadside Features on Low-Volume Roads in Oregon(2016-01) Ewan, Levi A.; Al-Kaisy, Ahmed; Hossain, FahmidCrashes are random events and can occur at any location along a roadway. On roadways with high traffic volumes, the more frequent occurrence of crashes permits the direct identification of high-frequency crash locations with the use of historical data. On low-volume roads, crash occurrence, particularly the occurrence of crashes with fatal and serious injuries, is less frequent. There is a need to understand better the risks associated with geometric and roadside features along low-volume roadways in order to identify locations where preventive countermeasures may be employed. This paper describes the collection and analysis of a large sample of data from low-volume roads in Oregon to quantify the effects of geometric and roadside features on crash occurrence and associated risks. The effects of lane width, shoulder width, grade, side slope, fixed objects near the roadway, and horizontal and vertical curves have been quantified. For the low-volume road sample, roads with lanes less than 12 ft wide have a much higher crash risk than do roads with standard 12-ft lanes. Similarly, roads with narrow or no shoulders tend to have much higher crash rates than roads with shoulders 4 ft or 5 ft wide. Crash risk is shown to be much higher on curves with higher degrees of curvature compared with curves with smaller degrees of curvature.Item Measuring Performance on Two-Lane Highways: Empirical Investigation(2017-01) Al-Kaisy, Ahmed; Jafari, Amirhossein; Washburn, ScottThis paper presents an empirical investigation into several performance measures for operational analysis on two-lane highways. The performance measures investigated are average travel speed, average travel speed to free-flow speed, percent followers, followers flow, followers density, percent impeded, impeded flow, and impeded density. Field data from 16 study sites in the states of Montana, Idaho, Oregon, and North Carolina representing Class 1, Class 2, and Class 3 highways were used in this study. The level of association between performance measures and some of the most important traffic variables was examined with graphical and statistical techniques. The traffic variables investigated in this study included combined flow in both directions of travel; proportion of traffic in the direction of travel, called in this study “traffic split”; percentage of heavy vehicles; and speed variance. Study results suggest that speed-related measures have weak associations with traffic variables compared with headway-related measures. Further, compound measures involving headway and traffic flow or density exhibited the highest associations with traffic variables. With regard to two-lane highway type, higher associations are exhibited at Class 1 sites compared with Class 2 and Class 3 sites. Performance measures showed the highest associations with combined flow and traffic split.Item Traffic Operations on Rural Two-Lane Highways: A Review on Performance Measures and Indicators(2018-05) Al-Kaisy, Ahmed; Jafari, Amirhossein; Washburn, Scott; Lutinnen, Tapio; Dowling, RichardTwo- lane highways constitute a large proportion of the highway system in the United States, particularly in rural areas. Performance evaluation on those highways is the basis for planning, upgrade, and improvement programs. Such evaluations are conducted using performance measures that should ideally be correlated to performance determinants on those highways. Unlike other highway facilities, two-lane highway performance is notably affected by the platooning phenomenon, which is believed to be a function of traffic level and passing opportunities. Over the last couple of decades, several studies have addressed performance measures on two-lane highways, and are mainly driven by the reported limitations of the current measures used by the Highway Capacity Manual (HCM). This review aims to summarize the performance measures that have been published in the literature or used in practice both in the United States and abroad. The review starts with an historical overview of the HCM performance measures since its inception in 1950. It then discusses the most important criteria for measures to be more effective in describing performance, before presenting the review results for measures that have been proposed in literature or reported as being used in practice. Finally, a subjective assessment of all performance measures against the set of criteria outlined in the article is presented. The review presented in this paper provides information that is valuable for practitioners and researchers in understating the alternative measures for assessing performance on two-lane highways, and the limitations and merits associated with those measures.Item Performance measures on two-lane highways: Survey of practice(2018-11) Al-Kaisy, Ahmed; Jafari, Amirhossein; Washburn, Scott; Lutinnen, Tapio; Dowling, RichardTwo-lane highways constitute a significant component of the highway system and serve an essential function for the movement of people and goods. The Highway Capacity Manual is primarily used for operational analysis on two lane highways in the U.S. and Canada. As part of a project sponsored by the National Cooperative Highway Research Program for improving two-lane highway operational analysis methodology, a practice survey was conducted to gather information on agency experiences in regards to performance measurement on two-lane highways. The survey was sent to all state Departments of Transportation in the United States and Canada. A total of 35 usable responses were received, representing 25 states and 4 Canadian provinces. This paper summarizes the results of the agency survey and presents the most important findings. Results suggest that the top three criteria for good performance measures are: sensitivity to traffic conditions, sensitivity to road conditions, and relevance to road user perception. Further, agencies identified average travel speed as the most relevant traffic flow aspect to two-lane highway operations. Other performance measures that were found meritorious were volume-to-capacity ratio and flow rate, for class I and class II highways, respectively, versus the latter measures and percent-time-spent-following for class III highways.Item Prioritization Scheme for Proposed RWIS Sites: Montana Case Study(2017-08) Al-Kaisy, Ahmed; Ewan, Levi A.A model for prioritization of new proposed environmental sensor station (ESS) sites is developed and presented in this paper. The model assesses the overall merit (OM) of a proposed ESS site as part of a Road Weather Information System (RWIS) using weather, traffic, and safety data among other variables. The purpose of the proposed model is to help in selecting optimum sites for new ESS locations, which is important in guiding RWIS system expansion. Inputs to the OM model include weather index (WI), traffic index (TI), crash index, geographic coverage, and opportunistic factors. The WI at a proposed site is determined using multiple indicators of weather severity and variability. The crash index, another major input to the OM model, incorporates crash rate along the route and the percentage of weather-related crashes over the analysis period. The TI, in turn, reflects the amount of travel on the highway network in the area surrounding the proposed ESS site. The fourth input to the merit model accounts for the ESS existing coverage in the area where the proposed site is located, while the fifth and last input is concerned with the availability and ease of access to power and communications. Model coefficients are represented by weights that reflect the contribution of each input (variable) to the OM of the ESS site. Those weights are user-specified and should be selected to reflect the agency preferences and priorities. The application of the proposed merit model on sample sites in Montana demonstrated the utility of the model in ranking candidate sites using data readily available to highway agencies.Item Motorists' voluntary yielding of right of way at uncontrolled midblock crosswalks with rectangular rapid flashing beacons(2018-07) Al-Kaisy, Ahmed; Miyake, Guilherme T.; Staszcuk, Joey; Scharf, DanielleThis article presents an investigation into the motorists' voluntary yielding behavior to bicycles and pedestrians at uncontrolled midblock crosswalk locations. Two study sites in the state of Montana with light emitting diode (LED) rectangular rapid flashing beacons (RRFB) warning devices were used in this investigation. Video records were acquired at the two study sites and video data was reduced to investigate the motorist's voluntary yielding of right of way to pedestrians and bicycles as they approach the crosswalks. The study found that the motorists' voluntary yielding increased with the activation of the RRFB devices at the two study sites. This finding is very consistent with the few recent studies that reported increases in the overall yielding behavior associated with the use of those devices. The study also found that the waiting position of crosswalk user(s), the presence of children and elderly, the number of crosswalk users, and peak periods are all important factors that affect the voluntary yielding behavior of motorists. Study results suggest that the visibility of crosswalk users by motorists is very important consideration in the selection of crosswalk location. Further, the study recommends the push-button RRFB devices be located as close as practically possible to the roadway for increased device activation and motorists' voluntary yielding.Item Detection of Pathogenic and Non-pathogenic Bacteria in Drinking Water and Associated Biofilms on the Crow Reservation, Montana, USA(2018-07) Richards, Crystal L.; Broadaway, Susan C.; Eggers, Margaret J.; Doyle, John T.; Pyle, Barry H.; Camper, Anne K.; Ford, Tim E.Private residences in rural areas with water systems that are not adequately regulated, monitored, and updated could have drinking water that poses a health risk. To investigate water quality on the Crow Reservation in Montana, water and biofilm samples were collected from 57 public buildings and private residences served by either treated municipal or individual groundwater well systems. Bacteriological quality was assessed including detection of fecal coliform bacteria and heterotrophic plate count (HPC) as well as three potentially pathogenic bacterial genera, Mycobacterium, Legionella, and Helicobacter. All three target genera were detected in drinking water systems on the Crow Reservation. Species detected included the opportunistic and frank pathogens Mycobacterium avium, Mycobacterium gordonae, Mycobacterium flavescens, Legionella pneumophila, and Helicobacter pylori. Additionally, there was an association between HPC bacteria and the presence of Mycobacterium and Legionella but not the presence of Helicobacter. This research has shown that groundwater and municipal drinking water systems on the Crow Reservation can harbor potential bacterial pathogens.
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