Title from PDF of title page (University of Missouri--Columbia, viewed on Feb. 12, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Praveen K. Edara. Includes bibliographical references.

There are over 5 million reported motor vehicle collisions annually in the United States, and while crash rates and fatality rates have declined in the past decades, rates in work zones are disproportionately high. There are strict standards for evaluating the crashworthiness of temporary traffic control devices, but not for evaluating drivers’ comprehension of existing or novel device deployments. This dissertation presents a series of three experiments evaluating driver comprehension for existing and novel traffic control devices conducted in a work zone setting. This evaluation is further expanded by decomposing the task of comprehending traffic control into the three subtasks of detection, localization, and identification. Methods are proposed for conducting a computer-based experiment with still image stimuli to measure participant performance at each of these subtasks. Next, procedures for categorizing localization responses and accounting for variation in participants physical responses are explored. Lastly, an application of Item Response Theory toward the evaluation and comparison of participant comprehension is demonstrated. It is hoped that these methods and procedures can be used by future researchers and experimenters to compare novel temporary traffic control devices and systems to inform future design.

Thesis (Ph. D.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on June 8, 2009) Vita. Includes bibliographical references.

Master of Science / Department of Civil Engineering / Eric J. Fitzsimmons / Each year maintenance and rehabilitation occur on interstates and highways to repair damage, improve rideability, and increase safety. To perform many of these activities a short or long-term work zone is required. However, short and long-term work zones can have significant impacts on traffic flow, especially during peak travel times. To mitigate the impact of work zones, the Kansas Department of Transportation (KDOT) has developed a lane closure guide to assist KDOT personnel and contractors in determining times during the day that a lane can be closed to traffic. The existing lane closure guide was comprised of limited data sources and assumptions based on past traffic counts. The purpose of this research study was to evaluate the existing guide and update it using a consistent data source that reflects current roadway conditions. During the evaluation of the existing lane closure guide, several inconsistencies with traffic counts, directional splits, and adjustment factors were found. To eliminate the consistencies, data from the Kansas City Traffic Management Center was used. During the procedure of updating the lane closure guide a repeatable data extraction process and a quality assurance/quality control process were utilized. In addition to updating the KDOT lane closure guide, sensor data verification was performed on one KC Scout sensor on K-10 using road tubes. The data from the road tubes was then compared to the data extracted from KC Scout during the same time interval. The comparison found the road tubes and KC Scout counted statistically the same number of cars for the chosen interval. However, the comparison found the road tube’s average speed for chosen interval to be on average 10 percent higher than KC Scout, which was statistically significant.

Work zones are visually and physically complex environments, requiring that drivers maintain control of their vehicle and comprehend atypical and often discontinuous traffic control devices to safely navigate appropriate paths. Freeway diverges represent particularly difficult work zones areas. This thesis investigates current methods of delineating diverges in freeway work zones to determine important characteristics of these methods for future research. A virtual environment was constructed with two ramp geometries: a freeway continuing straight and one curving left. Still images of work zones on these geometries were created using drums spaced 10 ft apart, drums spaced 40 ft apart, drums spaced 40 ± 2 ft apart, and portable concrete barriers. These alternatives were used to construct temporary ramps that were either open or closed. 39 participants were asked to identify whether the ramp was open or closed and their responses were recorded to evaluate the performance of each alternative. Results indicate the importance of the Gestalt principles of closure, proximity, and continuity in perception of temporary exit ramps in work zones. These results will be used to guide future research into methods of delineating diverges in freeway work zones.

Highway lane closures cause reductions in the traffic throughput which lead to premature queuing. To minimize user delays, contractors are required to keep highway lanes open during the peak traffic hours and work at nights. However, these limitations can reduce the quality of the work and extend project duration. Finding a right balance between the times that the lanes can be closed and the times they should be kept open can increase the efficiency of the contractors’ work. Over 100 hours of throughput data were collected in two phases from 2007 to 2010 from Southern Ontario highways. Using regression analysis, a generic and a highway specific model were developed predicting the mean throughput in approximately 50% of cases within one hundred vehicles per hour per lane of the actual mean. Also the Simplified Work Zone User Delay Analysis model, developed in Phase 1, was refined to investigate the resulting queues.

Highway lane closures cause reductions in the traffic throughput which lead to premature queuing. To minimize user delays, contractors are required to keep highway lanes open during the peak traffic hours and work at nights. However, these limitations can reduce the quality of the work and extend project duration. Finding a right balance between the times that the lanes can be closed and the times they should be kept open can increase the efficiency of the contractors’ work. Over 100 hours of throughput data were collected in two phases from 2007 to 2010 from Southern Ontario highways. Using regression analysis, a generic and a highway specific model were developed predicting the mean throughput in approximately 50% of cases within one hundred vehicles per hour per lane of the actual mean. Also the Simplified Work Zone User Delay Analysis model, developed in Phase 1, was refined to investigate the resulting queues.

Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 11, 2006) Includes bibliographical references.

About 20 percent of the U.S. National Highway System is under construction during the peak summer roadway season. Fifty percent of all highway congestion is attributed to nonrecurring conditions and work zones are estimated to account for nearly 24 percent of nonrecurring delay. Work zones account for two percent of roadway crashes and more than 1,000 fatalities per year. Motorists across the United States have increasingly voiced their displeasure with work zones and the associated delay. This has posed a challenge to transportation officials and contractors as they are faced with finding ways to reduce work zone delay. A key to addressing this challenge to minimize motorist delay during construction and maintenance operations is to recognize these impacts well in advance. In order to meet this challenge, work zone strategy evaluations are necessary to understand the type, severity, and extent of impacts associated with various strategies. One major tool used to aid in conducting these evaluations is computer simulation. There are many simulation packages in existence, some of which are designed specifically for work zone analysis. These packages include, for example, QUEWZ, QuickZone, and CA4PRS. This research focuses on the evaluation of these three simulation packages along work zones located on four interstate highway segments on I-91 and I-95 in New England. The evaluation consists of comparing simulation results to field observations in the work zones. The queue lengths estimated by QuickZone and QUEWZ are compared to queue lengths observed in the work zone. Maximum rehabilitation production rates estimated by CA4PRS will be compared to actual production rates recorded in the work zone. This evaluation will allow for a determination to be made as to whether or not these simulation packages produce accurate estimates. In addition to accuracy, the evaluation also sheds light on the user-friendliness of each simulation model as well as other parameters such as data requirements and analysis time. Major results of this evaluation include: • QUEWZ and QuickZone are user-friendly work zone simulation models. • The estimations of queue length provided by QuickZone and QUEWZ for the four sites considered in this research were found to be comparable to the field observations. • CA4PRS is a user-friendly simulation model. However, the data required to perform an analysis is not as always easy to obtain. In addition, these simulated results of maximum rehabilitation production rates are not easily compared to observed data which are not typically available. This research should be helpful to guide state and local officials in New England in the selection of simulation models to assess work zone strategies for roadway reconstruction and rehabilitation projects in New England.

In recent years, there has been a considerable increase in the amount of construction work on the U.S. national highways. Most of the work undertaken is the reconstruction and rehabilitation of the existing transportation networks. Work zones in the United States are likely to increase in number, duration and length due to emphasis on repair and highway reconstruction as a significant portion of all federal-aid highway funds are now geared toward highway rehabilitation. The challenge of mobility is particularly acute in work zone areas as road repair and construction intensifies traffic issues and concentrates them in specific locations and at specific times. Due to the capacity drop, which is the result of lane closure in work zone area, congestion will occur with a high traffic demand. The congestion increases number and severity of traffic conflicts which raise the potential for accidents; furthermore traffic operational properties of roadway in work zone area become worse. Intelligent Transportation System (ITS) technologies have been developed and are being deployed to improve the safety and mobility of traffic in and around work zones. In several states in the US, the use of Dynamic Merge Controls also known as Dynamic Lane Merge (DLM) system has been initiated to enhance traffic safety and to improve traffic flow in work zone areas. The DLM usually takes two forms; dynamic iii early merge and dynamic late merge. The use of variable speed limit (VSL) systems at work zones is also one of those measures. VSL systems improve safety by helping the driver in determining the maximum speed that drivers should travel. Besides adding improvement to safety, they are also expected to improve mobility at the work zones. The main goal of this study is to evaluate the safety and operational effectiveness of the dynamic merge systems i.e. the dynamic early lane merge and dynamic late lane merge, in the presence of VSL system. More specifically, the VISSIM model is utilized to simulate a twoto-one lane configuration when one out of the two lanes in the work zone is closed for traffic. Six different scenarios were adopted to assess the effectiveness of these scenarios under different traffic demand volumes and different drivers‟ compliance rates to the messages displayed by the systems. These scenarios are;  Work Zone without VSL and without SDLMS or the current Motorist Awareness System (MAS)  Work Zone with VSL and without SDLMS  Work Zone with VSL and Early SDLMS  Work Zone with VSL and Late SDLMS  Work Zone with early SDLMS and without VSL  Work Zone with late SDLMS and without VSL iv An already calibrated and validated VISSIM model for Simplified Dynamic Lane Merge System (SDLMS) in accordance with the real life work zone was modified with a VSL through Vehicle Actuated Programming (VAP) code. Three different logics were coded each for VSL alone, early SDLMS+VSL and late SDLMS+VSL. All these logics were fine tuned with several test runs before finalizing it for the final simulation. It is found through the simulation of above mentioned scenarios that for low and medium volume levels (V0500, V1000 and V1500), there is no significant difference between the Maintenance of Traffic (MOT) plans for mean throughputs. However, for higher volume levels (V2000 and V2500), late SDLMS with and without VSL produced higher mean throughputs for all compliance rates and truck percentages except when the demand volume was 2,500 vph and compliance of 60%, where it produces the significantly lower mean throughputs. In terms of travel time through the work zone, results indicated that there is no significant difference between MOT types for demand levels of V0500 and V1000 when compliance is 40% or less but for compliance of 60% and more, only demand volume level that is not significantly different from other MOT types is V0500. This study revealed that VSL increases travel time through the work zone. This might be due to non-compliant vehicles that follow the compliant vehicle v ahead unless they find a sufficient gap in adjacent lane to pass the compliant vehicle. It is also found out that VSL makes the system safer at higher volumes (2,000 vph and 2,500 vph). This was observed through safety surrogate measures selected for this study. Another outcome of this study is that the addition of VSL to the dynamic merge systems helps in improving the overall safety of the system by lowering speed variances and deceleration means of the vehicles travelling through the work zone. The passage of traffic through the work zone is made safer when a speed control is integrated to a dynamic merge system. It can be inferred from the simulation results that integrated SDLMS and VSL systems have better performance in terms of traffic mobility and safety than existing individual controls and also show that the integrated SDLMS and VSL system has more potential than each individual systems.