M.Ing. (Transportation) / Please refer to full text to view abstract

The proportion of individuals aged 65 and over is growing at an astronomical rate in the United States, and some estimate that this demographic age group will double by the year 2025. Aging adults are primarily dependent on the personal automobile as their main source of transportation. Older adults and adults nearing retirement age also tend to reside in suburban neighborhoods and rely heavily on personal vehicles. Since most of the United States is characterized by automobile dependent suburbanization, where the majority of development is suburban low-density sprawl, this may become problematic for aging populations who may be uncomfortable driving longer distances and making more trips. These trends invite the question of whether the deck is stacked against individuals approaching retirement age (50-64) and aging populations (65 and up). This study examines aging populations’ mobility and determines whether they have different travel patterns than their younger cohorts. Additionally, this investigation explores whether or not travel patterns across age groups result in differential access to particular goods and services, as well as differences in travel environment characteristics in a metropolitan area. This research proposes an approach based on Time Geographic Density Estimation (TGDE) to identify activity spaces across different age cohorts in order to identify differences in the mobility and travel behavior of aging adults. TGDE is an established technique in the literature, which blends the notion of activity spaces with the computation of probabilistic potential path trees along a transportation system. In this way it establishes an ‘extent’ or overall mapping of the activity space of an individual, but is able to further refine that extent to identify the most likely places they are able to visit within that geography. Data on origin and destination trips and travel times are taken from the National Household Travel Survey (NHTS) Florida add-on for the study area of Orlando Metropolitan Statistical Area (MSA). Transportation is an important consideration in planning for aging populations, and analyzing differences in how older adults travel compared to their younger counterparts can offer insight into the diverse needs of this group. / A Dissertation submitted to the Department of Geography in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester 2017. / April 28, 2017. / Accessibility, Aging Populations, Transportation / Includes bibliographical references. / Mark Horner, Professor Directing Dissertation; Jeffrey Brown, University Representative; Christopher Uejio, Committee Member; David Folch, Committee Member.

Recently, in the United States, roundabouts have been used to replace signalized and unsignalized intersections because the use of roundabouts has safely reduced crash severity and fatality at intersections by eliminating or altering conflict types and forcing drivers to reduce their speed as they drive in and through it. Generally, in Florida, due to the recent introduction of roundabouts and the complexity of some roundabouts (especially multi-lane roundabouts), drivers are most times not familiar with this type of intersection and therefore involve in a crash. Therefore, it is necessary to evaluate the safety effects of roundabout amongst drivers and especially aging drivers since it is projected by the United States Census Bureau, that the population of persons aged 65 and above in Florida is expected to be more than 26% of the total population by the year 2025 and by the year 2030 all the baby boomers will be older than age 65. Thus, the objectives of this study were to evaluate the effectiveness of roundabouts among drivers by comparing the crash severity of roundabout crashes involving aging drivers versus their young and middle-aged counterparts and to determine the relationship between the crash frequency, the geometric characteristics of roundabouts and the signage of roundabouts .In order to achieve these objectives, the type and severity of roundabout crashes, as distributed according to participant age will be investigated Binomial logistic regression model was used to evaluate injury severity differences in roundabout crashes amongst drivers of different age groups while evaluating the differences in factors relating to roundabout crashes which includes the time of the day, day of the week, the type of roundabout, weather conditions, lighting conditions, the geometric design of the roundabout, vehicle speed and the crash's at-fault driver age. Also, the negative binomial regression model was used to determine the relationship between the total number of crashes, the roundabout speed, the geometric conditions and signage of the roundabouts selected for the count study. The results from this study indicate that vehicle speed and average annual daily traffic are the most important factors affecting the severity of crashes among all age groups at roundabouts and that the total number of crashes on roundabouts are affected by the traffic volume, the number of circulatory roadway lanes, the number of legs, the roundabout speed, inscribed circle. diameter, and the presence of signages and signals such as chevron, pedestrian sign, approach marking, lane use control symbol marking and pavement word. For aging drivers, the number of vehicles involved in the crash, the vehicle speed of the at-fault driver and the type of crash are significant at 95% confidence interval in affecting their crash severity while the annual average daily traffic is the only significant factor at 95% confidence interval affecting the frequency of aging driver crashes at roundabout This study focuses on developing recommendations for roundabout implementation, improved design guidelines and additional recommendations for improved for improved safety of drivers in the State of Florida. / A Thesis submitted to the Department of Civil and Environmental in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester 2018. / November 26, 2018. / Includes bibliographical references. / Lisa K. Spainhour, Professor Directing Thesis; Eren E. Ozguven, Committee Member; Maxim Dulebenets, Committee Member.

Evacuating individuals and allocating space in shelters are complex tasks that depend on disaster characteristics, roadway network characteristics, the demographics and socioeconomic status of people in the affected region, as well as the effectiveness of the emergency plans. This problem becomes even more challenging when special needs (access and functional needs) populations and those with pets are considered since they may require more time in the event of an evacuation along with more space in shelters. Satisfying the needs of aging victims during emergency evacuations is critical and requires extra attention in the presence of highly uncertain disaster conditions. During Irma, it was very hard to manage the evacuation of aging people who had disabilities and mobility restrictions, did have special needs or pets. This study develops a Geographical Information Systems (GIS)-based methodology to measure and assess the transportation accessibility of these critical facilities through a diverse set of case study applications in the State of Florida. This research presents a timely evaluation and assessment of aging-focused evacuations towards providing better decision support during emergency transportation operations. This analysis is applied on a case study application set in Florida with a focus on the delays, evacuation travel times and critical bottlenecks, which can be vital for aging victims’ safety and survival. This study also emphasizes the use of GIS-based maps and modeling scenarios in support of emergency evacuation operations, in order to both satisfy the needs of aging people and account for real-world disruptions such as road closures. Additionally, a variety of scenarios are constructed to simulate evacuating 65+ and 85+ populations living in the evacuation zone, providing dynamic congested travel times. Finally, a capacitated p-median optimization model is implemented to maximize the accessibility and capacity of the existing shelters for 85+ populations with special needs (access and functional needs) or pets. Results indicate that the location and allocations of people to shelters are sensitive to demographics and roadway conditions, and the accessibility to shelters can be improved for this group of people based on optimization model results. A contribution of the research will be the evaluation of emergency evacuation performance of the transportation network under multiple disaster scenarios and the detailed modeling of key transportation facilities where special needs would take place. By exploring the use of multi-layered approach for emergency operations, this research will also increase the performance in evacuating aging people who has limitations. / A Dissertation submitted to the Department of Civil and Environmental Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester 2017. / November 7, 2017. / Includes bibliographical references. / Eren Erman Ozguven, Professor Directing Dissertation; Jeff Brown, University Representative; Ren Moses, Committee Member; John O. Sobanjo, Committee Member.

The accurate modeling of travelers' route choice decision making when faced with unreliable (risky) travel times is necessary for the assessment of policies aimed at improving travel time reliability. Two major objectives are studied in this thesis. The first objective is to evaluate the applicability of a process model to route choice under risk where the actual process of decision making is captured. Traditionally, we adopt "as-if" econometric models to predict people's route choice decisions. The second objective is to investigate travelers' capability to incorporate future real-time traffic information into their current route choice decision making. Two separate stated preference (SP) surveys were conducted for each objective. The first SP survey used an interactive map in a computer based test. The second SP survey used a full-scale high-fidelity driving simulator. Compared with econometric models, process models have been rarely investigated in travel decision making under risk. A process model aims to describe the actual de cision making procedure and could potentially provide a better explanation to route choice behavior. A process model, Priority Heuristic (PH), developed by Brand statter et al. (2006) is introduced to the travel choice context and its probabilistic version, Probabilistic Priority Heuristic (PPH), is developed and estimated in this study. With data collected from a stated preference (SP) survey which is based on an animated computer interface, one econometric model, Rank-Dependent Expected Utility (RDEU) model, and two other alternative models were compared with the PPH model in a cross validation test to investigate their data-fitting and predictive performance. Our results show that the PPH model outperforms the RDEU model in both data-fitting and predictive performance. This suggests that the process modeling paradigm could be a promising new area in travel behavior research. With the advance of information and telecommunication technology, real-time traffic information is increasingly more available to help travelers make informed route choice decisions when faced with unreliable travel times. A strategic route choice refers to a decision taking into account future diversion possibilities at downstream nodes based on real-time information not yet available at the time of decision-making. Based on the data collected from a driving simulator experiment and a matching PC based experiment, a mixed Logit model with two latent classes, strategic and non strategic route choice, is specified and estimated. The estimates of the latent class probabilities show that a significant portion of route choice decisions are strategic and subjects can learn to make more strategic route choice as they have more experience with the decision scenarios. Non-parametric tests additionally show that network complexity adversely affects travelers' strategic thinking ability in a driving simulator environment but not in a PC environment and a parallel driving task only affects strategic thinking ability in a difficult scenario but not a simple one. In addition, we find that people's strategic thinking ability are influenced by their gender and driving experience (mileage) in the non-parametric analysis, but not in the modeling work. These findings suggest that a realistic route choice model with real-time traffic information should consider both strategic and non-strategic behavior, which vary with the characteristics of both the network and the driver.

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A significant responsibility of officials involved in transportation planning is ensuring people's accessibility to critical facilities such as multi-modal terminals and emergency shelters. This challenging task depends on the available transportation infrastructure as well as the overall population, traffic, roadway and regional characteristics. Such planning takes on additional complexity when aging populations are considered because any extra time they incur reaching these facilities can be especially confounding in light of their potential health and other safety concerns. As such, there is a need for state/federal transportation plans to have a transportation assessment component that specifically focuses on the accessibility of aging people ('the aging population' can be thought of as those people aged 65+ in this study) to critical facilities. To accomplish this goal, this study first describes a Geographical Information Systems (GIS)-based methodology for measuring the aging population-focused accessibility to multi-modal facilities in Florida. Spatially detailed population block- and county-based accessibility scores are calculated with respect to key intermodal facility types (airports, bus stations, and railway and ferry stations), and visually assessed via GIS maps. Second, a spatial optimization model is presented which focuses on maximizing the accessibility of aging populations to the emergency shelters. For this purpose, a p-median optimization model is proposed in order to minimize the transportation cost (travel time or roadway network distance costs between the origins –centroids of population blocks- and destinations –emergency shelters) in the transportation network, and therefore providing maximum accessibility for aging adults to the emergency shelters. In this context, different transportation costs are used: (a) roadway network distance, (b) free flow travel time, and (c) congested travel time. This model is also extended towards a capacitated p-median model with hubs, which makes it possible to conduct an extensive evaluation of possible intermediate hub locations that can have a significant effect on the accessibility of those shelters. The knowledge obtained from this accessibility analysis can successfully contribute to the development of more reliable aging population-focused transportation plans, as the analysis points to specific areas where accessibility could be improved as well as those candidate locations that can be serve as additional emergency shelters and intermediate hubs. / A Thesis submitted to the Department of Civil and Environmental Engineering in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester 2015. / November 6, 2015. / Accessibility, Aging, GIS, Optimization, p-median, Spatial Optimization / Includes bibliographical references. / Eren Erman Ozguven, Professor Directing Thesis; Ren Moses, Committee Member; John O. Sobanjo, Committee Member.

The overall goal of this thesis was to provide a quantitative analysis of the operational and safety performances of roundabouts. The operational analysis of Florida roundabouts was conducted to determine the base capacity of different configurations of approaching lanes. Building upon the methodologies and findings of NCHRP 572 report, FHWA-SA-15-070 study and HCM 6th Edition, capacity models were calibrated to reflect Florida driving conditions for different roundabout lane configurations. The results indicated that Florida roundabouts were not congested, the gap acceptance parameters were within the range of the HCM 6th Edition with slightly higher average values of follow-up time. The study found out that the HCM 6th Edition models generally overpredicted the capacity of roundabouts in Florida. Safety performances were evaluated from the crash data of 34 roundabouts in Florida for a period of 5 years. The type of crashes, severity and contributing factors were analyzed to determine the relationship between the roundabout crashes severity with traffic and geometric parameters. Four types of crashes were found to be prevalent in the roundabouts (i.e. Rear-end, Angle, Sideswipe and Off-road crashes). The crashes were 77.4% PDO, 21.9% injury and only 3 fatal crashes. Results indicated that the crash severity was influenced by the number of vehicles involved in the crash, and diameters of the inscribed circle and central island. There was a 3.6 odds of a crash causing injury or fatality for an incident involving a single vehicle than it was for an incident involving more than one vehicle. The negative binomial model was developed to show the relationship between the total number of crashes at a roundabout with the traffic exposure, geometric, age, gender and weather parameters. The traffic volume (i.e. AADT) and inscribed circle diameter were significant variables in the proposed safety models at a 95% level of confidence. Generally the roundabouts were found to have few crashes consistent with the results from other studies. / A Thesis submitted to the Department of Civil Engineering in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester 2018. / October 26, 2018. / OPERATIONS, ROUNDABOUT, SAFETY / Includes bibliographical references. / Ren Moses, Professor Directing Thesis; Eren Erman Ozguven, Committee Member; Maxim Dulebenets, Committee Member.

Traffic crashes are one of the leading causes of death, substantial economic loss, and severe injuries for drivers. They also put lives of people at risk, cause severe traumas and incapacitating injuries, which usually require a painful healing process. Over the last 25 years, many researchers have recognized the necessity of delving into the nature of the traffic crashes. This necessity arises from the fact that developing methodologies to reduce crashes is vital to provide the public with safe and reliable transportation. From a transportation safety perspective, this problem becomes even more challenging and complex when aging populations are considered due to their cognitive, behavioral, and health limitations. Moreover, the number of aging road users and crashes involving aging drivers on Florida roadways are expected to increase in the near future due to their growing population in the state, which makes studies on aging population-involved crashes even more critical. With this motivation, unlike previous crash-focused traffic safety studies mostly focusing on the general population, this dissertation attempts to understand the unique nature of aging population-involved (aging-involved) crashes. Note that by "aging-involved", the crashes involving at least one 65 years and older individual are meant in this dissertation. The utmost importance is given to answering the following question: How do the aging-involved crashes vary compared to other age group-involved crashes? Given the limitations of existing traffic crash studies on addressing the needs of aging populations, this dissertation proposes several novel methodological approaches with the following objectives: • to discover the geo-spatial differences between aging- and other age group-involved crashes based on the comparison of high risk crash locations, • to identify the statistically significant factors influencing the aging-involved crashes using a multiple binary choice model-based approach, • to disclose the differences between crashes involving 50-64 and 65+ drivers in terms of involvement characteristics, spatial distribution, and significant factors causing those crashes, • to stratify the aging drivers by dividing them into three subgroups (65-69, 70-74 and 75+) in order to explore the differences among aging drivers, who are oftentimes evaluated as a homogeneous group, • to provide a spatiotemporal comparative investigation of the crashes involving aging drivers, passengers, bicyclists, and pedestrians, • to determine the factors that drive both the crash occurrence probability and the crash rate of aging drivers, passengers, bicyclists, and pedestrians, • to understand where and how far away people have crashes compared to where they live, and what the statistical nature of proximity of crash spots to the residence locations of crash occupants is. To the authors' knowledge, such a comprehensive investigation of aging population-involved crashes has not been conducted previously in the traffic safety field, which represents the novel contribution of this work. For this purpose, several methodological approaches were applied on both different counties in the State of Florida as well as the whole state. Aging-involved crashes were spatially and temporally investigated using GIS-based methodologies in order to discover the significant factors that affect those crashes using statistical modeling approaches. The most important findings of this work can be summarized as follows: • Aging-involved crashes differ from other age group involved crashes both spatially and temporally. • Aging-involved crash density maps have a unique geo-spatial pattern, which is different than the patterns of other age groups' crash density maps. • Spatial distributions of aging adults and aging-involved crashes are strongly correlated as indicated by the population factor approach. • Aging drivers in different age cohorts such as 65-69, 70-74, and 75+ do not constitute a homogeneous group and rather heterogeneous in terms of crash involvement. • There are significant differences in the effect of significant causal and spatiotemporal factors on the crash involvement not only between 65- and 65+ drivers, but also between stratified age groups of 65+ drivers. • Significant spatiotemporal variations in crash rates of different types of aging roadway users (e.g. driver, pedestrian, etc.) were captured. • Traffic safety of 65+ population compel spatially and temporally tailored remedies in order to address issues emerge at different roadway segments at weekdays and weekends. • Facility variables such as health facilities, religious facility, and supermarkets are highly influential on 65+ crashes, and hence roadways around these facilities should be particularly scrutinized by road safety stakeholders. • High aging-involved crash rate roadways are found to vary spatially depending on whether it is weekday or weekend. • The information obtained from crash spot –residence location proximity analysis can help in developing methodologies that can integrate population into crash frequency prediction methods. / A Dissertation submitted to the Department of Civil and Environmental Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester 2018. / October 26, 2018. / Aging, GIS, Human Factors, Spatial Analysis, Statistical Analysis, Traffic Safety / Includes bibliographical references. / Eren Erman Ozguven, Professor Directing Dissertation; Arda O. Vanli, University Representative; Ren Moses, Committee Member; John O. Sobanjo, Committee Member; Lisa Spainhour, Committee Member.

The ongoing debate within the Bus Rapid Transit (BRT) community over the relative importance of 'appropriate' design standards, the 'right' institutional setup and 'political will' to the success of projects obscures the larger importance of the planning process. Political leadership, institutions and design are important conditions that must be considered in the context of one another, but they are also conditions that will change and be influenced by the planning process. Drawing on case studies of the Janmarg BRT in Ahmedabad, and the Delhi BRT in India, I demonstrate the indirect and direct role of the planning process in influencing the outcome of BRT projects. My dissertation argues that planners too often treat the planning process as a one-dimensional sequence of steps in which design, institutions and leadership provide an unchanging framework in which planning proceeds. Planners however, can assert more influence over outcomes by re-framing the process as a three dimensional activity that considers not just the content and sequencing of the steps, but also requires decisions concerning approach (i.e. strategy and tactics) and timing (i.e. both moment of action and duration). This broader three-dimensional understanding of the planning process can be used to reshape design, institutions and leadership. A well-designed planning process has the potential to overcome institutional and design weaknesses and build political support leading to more viable and sustainable BRT systems.