Scholarship & Research
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Item Capacity investigation of all-way stop-controlled intersections(Montana State University - Bozeman, College of Engineering, 2022) Doruk, Dorukhan; Chairperson, Graduate Committee: Ahmed Al-KaisyDepending on traffic conditions, highway functional classification, sight distance, area setting, and other considerations, various traffic controls are used at the location of intersections. One of the essential traffic controls used at intersections is All-Way Stop Control (AWSC) which requires all vehicles to stop before entering the intersection. Proper capacity and headway estimations are essential for AWSC intersections to estimate the capacity. On the other hand, estimating the capacity of these types of intersections was always a challenging and essential task for a transportation engineer. Therefore, this research aims to develop a suitable methodology to estimate the capacity and empirically investigate the AWSC intersections. The literature review of this research identified many existing methodologies for estimating the capacity for unsignalized intersections; however, a few existing studies were for AWSC type of intersection, and others were outdated. Four days of intensive field data collection took place to identify the individual vehicle that entered and exited the intersection--the study site was characterized by single-lane approaches and high levels of vehicular and pedestrian traffic. Using strict protocols, collected data were processed at the individual vehicle. Then the collected data was extracted into a series of spreadsheets for analysis purposes. The method used several variables such as level of conflict, pedestrian activity, and type of movement at the intersection. The study resulted that the total intersection capacity varied between 400 and 1400 vehicles per hour. The study suggested that the wide range of capacity observations is primarily associated with the pedestrian crossing activity at the intersection of interest. Regarding movement type, the right-turn movement was not significantly affected intersection capacity. In contrast, the left-turn movement negatively affected the intersection capacity. Pedestrian traffic at the study site profoundly affected the mean saturation headways for saturation headways. The impact of the type of movement was found notable on the mean saturation headways, and the lowest mean was observed in right-turning vehicles.Item Inference of passenger ridership, O-D flows, wait times, and travel times using Wi-Fi and GPS signals(Montana State University - Bozeman, College of Engineerng, 2019) Videa Martinez, Aldo Alejandro; Chairperson, Graduate Committee: Yiyi WangReal-time data collection of transportation parameters is a vital element of research and industrial applications. A real-time ridership data collection would facilitate the planning of trips and optimization of routes for transportation agencies. Riders also would have the ability to plan their trips more easily. With the advent of smartphone technologies, societies have obtained a new infrastructure that is based on wireless networks. This infrastructure can be used as a platform to obtain information. In our case, we are exploring the Wi-Fi networks that surround a space to obtain traffic data. Our research focuses on scanning IEEE 802.11 networks with a sniffing software and then we classified the different signals into passengers and not passengers. To do so, we used the various attributes obtained with our sniffing software on a Raspberry Pi computer and filtered the signals that would not belong to passengers. Afterward, we implemented machine learning algorithms on the pre-processed data to understand the intrinsic nature of the data and evaluate if there could be some traits that would be utilized to perform an unsupervised classification that corresponded to the passengers' smartphones. In the unsupervised learning algorithm, the parameters were reduced into two with arithmetic operations and principal component decomposition. The results with the rule-based methodology are more accurate than the unsupervised methodology. We believe this is due to many router signals that are similar to the passengers' smartphones. Our proposed methodology has some limitations like some riders not carrying smartphones, and overestimation resulted from the noise of other signals. However, with the devices that were detected, we have demonstrated that the time of detection is accurate which helped us infer the origin-destination flows from a portion of our subjects. Additionally, we used the GPS traces to estimate travel time between buses and wait time of passengers at a bus stop.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 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 Estimating quality of traffic flow on two-lane highways(Montana State University - Bozeman, College of Engineering, 2008) Karjala, Sarah Renee; Chairperson, Graduate Committee: Ahmed Al-KaisySince the publication of the 2000 Highway Capacity Manual (HCM), there have been several studies that indicate that the HCM equations for Percent Time-Spent- Following (PTSF) on two-lane highways do not correspond to field-based measurements. This discrepancy was the motivation for this research project. The purpose of this project was two-fold. First, it aimed to find an alternative performance measure to PTSF that could be measured directly in the field and could adequately describe the quality of traffic flow. Secondly, the project aimed to investigate the inter-vehicular interaction between consecutive vehicles traveling on the same lane of two-lane rural highways. Both studies were empirical in nature and utilized field data gathered from rural two-lane and four-lane highways in the state of Montana. Six performance measures for two-lane highways were investigated; they were: average travel speed, average travel speed of passenger cars, average travel speed as a percent of free-flow speed, average travel speed of passenger cars as a percent of free-flow speed of passenger cars, percent followers, and follower density. The performance measures were evaluated based on their level of association with major platooning variables. Among all performance measures investigated, follower density and percent followers exhibited the highest correlation to platooning variables, respectively. Overall, follower density was recommended as the best performance measure for two-lane highways. Based on the fact that follower density is a headway-based service measure, the second study aimed to achieve a better understanding of car-following interaction on two-lane rural highways. Car-following interaction was studied by examining headway distributions, speed-headway relationships, and percent followers and flow relationships. The study found that car-following interaction generally ceases when headways exceed a value of approximately six seconds. Also, a significant proportion of drivers choose to maintain relatively short headways while following other vehicles on two-lane highways regardless of passing restrictions.