Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item An investigation of operational performance on two-lane highways(Montana State University - Bozeman, College of Engineering, 2018) Jafari, Amirhossein; Chairperson, Graduate Committee: Ahmed Al-KaisyA high percentage of the US road networks are two-lane highways. The Highway Capacity Manual (HCM) is the standard reference used in the US for traffic analysis of such highways (HCM 2016). This manual uses a qualitative measure called 'Level of Service (LOS)' to show the quality of traffic flow on the highway network. Performance measures are used as indicators of the LOS in the HCM. The current manual uses Average Travel Speed (ATS), Percent Time Spent Following (PTSF), and Percent Free Flow Speed (PFFS) for measuring LOS on two-lane highways. However, several studies reported that the HCM methodology falls short in several aspects including the performance measure used for operational analysis on two-lane highways. Moreover, the current guidelines of the HCM regarding passing lanes are very limited and based on studies conducted more than three decades ago (Harwood and St. John 1985, 1986). Constructing a passing lane is expensive and there is a need to use accurate methods for the design of such facilities. Therefore, the goal of this study is to examine new performance measures for operational analyses of two-lane highways as well as developing new guidelines for the design of passing lanes. Multiple investigations were conducted using field data from four states in the US as well as microscopic traffic simulation software, SwashSim. Using field data and statistical analysis as well as the results of a survey, the most appropriate performance measures were selected. Additionally, traffic simulation software was used to investigate the operational improvement of passing lanes. Optimum length and effective length of passing lanes were investigated. Optimum length has been used to refer to the length that would bring most operational benefits given the amount of passing lane investments while effective length is defined as the length of two-lane highway over which the effect of a passing lane extends. Moreover, the operational efficiency of different passing lane design configurations were examined to identify the most appropriate length and spacing to be used in the planning and design of passing lanes. In addition, the operational performance of 2+1 roads was investigated in this study and some guidelines for design of these facilities are provided. 2+ 1 highways have one lane in each direction of travel and the middle lane alternates between the two directions.Item Modeling chlorine concentrations in municipal water systems(Montana State University - Bozeman, College of Engineering, 1985) Murphy, Scott BrianItem Effect of variation of member stiffness on behavior to timber bridge floor systems(Montana State University - Bozeman, College of Engineering, 1985) Riple, Arne BengtThis paper investigates the effects incurred in a bridge floor system resulting from variation in member stiffnesses. If the stiffness in one stringer is reduced, without reducing the stiffness in the other members, a higher load must be carried by the nonreduced members. The increased loading condition results in reduced capacity for the floor system. The study is accomplished using a computer simulation to analyze the member reactions in the floor system. Using a structural grid as a model for the bridge floor, a matrix solution based on the stiffness method is solved by computer. Figures are presented to show the effects on member reactions resulting from variation in stiffness and loading conditions. Results show the effects occurring in both exterior and interior stringers as well as in the floor planks. The governing effects from these members are combined to show the effects in the floor system. Reducing the stiffness in an exterior stringer results in a greater reduce tion in capacity of the floor system, compared to reduction in capacity due to reduction in an interior stringer.