http://www.rssboard.org/rss-specification 720 https://escholarship.org/uc/its_ds/rss Recent eScholarship items from Dissertations Fri, 15 May 2026 05:03:44 +0000 https://escholarship.org/uc/item/9b51w7h6 Evacuations are a primary transportation strategy to protect populations from natural and humanmade disasters. Recent evacuations, particularly from hurricanes and wildfires, have exposed three critical evacuation challenges: 1) persistent evacuation non-compliance to mandatory evacuation orders; 2) poor transportation response, leading to heavy congestion, slow evacuation clearance times, and high evacuee risk; and 3) minimal attention in ensuring all populations, especially those most vulnerable, have transportation and shelter. With ongoing climate change and increasing land development and population growth in high-risk areas, these evacuation challenges will only grow in size, frequency, and complexity, further straining transportation response in disaster situations. https://escholarship.org/uc/item/9b51w7h6 Mon, 11 Jan 2021 00:00:00 +0000 Wong, Stephen D. https://escholarship.org/uc/item/6wh1v7cj Electric powered two-wheel bicycles, while extremely popular in China, have been recently banned by policy makers due to safety, congestion, and environmental concerns. This study investigates the tremendous growth of electric two wheel bicycles in China and compares and quantifies their environmental and safety impacts with the impacts of alternative modes of transportation, such as traditional bicycles, public transportation, or personal cars. The research also analyzes the benefits of electric two wheel bicycles, such as increased mobility and access to opportunities. Additionally, the author looks at the impacts of prohibiting the use of electric bicycles. Two case studies are carried out in Kunming and Shanghai, cities that have similar electric bicycle use but with very distinct differences. https://escholarship.org/uc/item/6wh1v7cj Thu, 26 Mar 2020 00:00:00 +0000 Cherry, Christopher R. https://escholarship.org/uc/item/7n29n303 <p>Energy use and emission factors for passenger transportation modes typically ignore the total environmental inventory which includes vehicle non-operational components (e.g., vehicle manufacturing and maintenance), infrastructure components, and fuel production components from design through end-of-life processes. A life-cycle inventory for each mode is necessary to appropriately address and attribute the transportation sector’s energy and emissions impacts to reduction goals instead of allowing tailpipe emissions to act as indicators of total system performance.</p><p>The contributions of U.S. passenger transportation modes to national energy and emissions inventories account for roughly 20% of U.S. totals, mostly attributed to gasoline consumption. Furthermore, world consumption of primary energy amounted to 490 EJ in 2005 with the U.S. responsible for 110 EJ, or 21% of the total. This means that passenger transportation in the U.S. accounts for roughly 5% of global primary... https://escholarship.org/uc/item/7n29n303 Tue, 18 Nov 2008 00:00:00 +0000 Chester, Mikhail V https://escholarship.org/uc/item/5wg9j6z7 <p>Various theories have been proposed to describe vehicular traffic movement in cities on an aggregate level. They fall short to create a macroscopic model with variable inputs and outputs that could describe a rush hour dynamically. This dissertation work shows that a macroscopic fundamental diagram (MFD) relating production (the product of average flow and network length) and accumulation (the product of average density and network length) exists for neighborhoods of cities in the order of 5-10km2. It also demonstrates that conditional on accumulation large networks behave predictably and independently of their origin-destination tables. These results are based on analysis using simulation of large scale city networks and real data from urban metropolitan areas. The real experiment uses a combination of fixed detectors and floating vehicle probes as sensors. The analysis also reveals a fixed relation between the space-mean flows on the whole network and the trip completion... https://escholarship.org/uc/item/5wg9j6z7 Tue, 15 Jul 2008 00:00:00 +0000 Geroliminis, Nikolaos https://escholarship.org/uc/item/84n3350n <p>Two freeway bottlenecks, each with a distinct geometry, have been investigated in an effort to understand traffic conditions leading to capacity losses (i.e., breakdown). One bottleneck is formed by a horizontal curve and the other by a reduction in travel lanes. These bottlenecks are shown to exhibit breakdowns after queues form immediately upstream. The vehicle accumulations that arise near these bottlenecks are shown to be good proxies for the mechanisms that trigger breakdowns. Evidence is provided to show that these losses can be recovered, postponed or even avoided entirely by controlling the accumulations. An algorithm for estimating vehicle accumulations has been developed in this dissertation. This algorithm? estimates are obtained from the counts made by ordinary detectors (e.g. inductive loops) placed in series. The accumulations estimated are those that arise on the intervening (freeway) segments between the detectors. These estimates can be obtained in real-time... https://escholarship.org/uc/item/84n3350n Wed, 26 Oct 2005 00:00:00 +0000 Chung, Koohong https://escholarship.org/uc/item/3js9x18d <p>This research describes field studies of how on-ramp metering can increase the capacity of freeway merges. Some effects of on-ramp metering have been known for a long time. We have known that on-ramp metering can 1) increase freeway flow and speed upstream of a merge; and 2) reduce system-wide delay by alleviating gridlock-causing queues that have blocked off-ramps. However, past studies have not conclusively shown that on-ramp metering can increase the maximum outflow (capacity) of freeway merges. The experiments conducted in the present study verify that on-ramp metering can increase freeway merge capacities. Detailed traffic data collected from videos for more than 30 rush periods at two merge bottlenecks unveil six major research findings: 1) merge capacity diminishes after merges became active bottlenecks; 2) the mechanism of "capacity drop" has been identified and was found to be reproducible across all days and it both sites. By metering the on-ramp in certain strategic... https://escholarship.org/uc/item/3js9x18d Wed, 26 Oct 2005 00:00:00 +0000 Rudjanakanoknad, Jittichai https://escholarship.org/uc/item/9c3330tt <p>Thirty years ago scholars first presented convincing evidence that local officials use biased travel demand forecasts to justify decisions based on unstated considerations. Since then, a number of researchers have demonstrated convincingly that such forecasts are systematically optimistic-often wildly so-for reasons that cannot be explained solely by the inherent difficulty of predicting the future. Why do modelers-professional engineers and planners who use quantitative techniques to predict future demand for travel and estimate its potential impact on built and proposed transportation facilities-generate biased forecasts and otherwise tolerate the misuse of their work? On initial consideration, it is tempting to surmise that corrupt modelers are responsible for biased forecasting. Indeed, corruption is the most common explanation of forecasting bias and tales of mercenary behavior are all too common in the field. Data from in-depth interviews with twenty-nine travel demand... https://escholarship.org/uc/item/9c3330tt Wed, 12 Oct 2005 00:00:00 +0000 Brinkman, Anthony P. https://escholarship.org/uc/item/6wk3t20s <p>Urban planners are increasingly concerned about the sprawling suburban development in metropolitan areas around the world, which they often blame for growing traffic congestion and excessive highway investment needs. This dissertation seeks to shed light on this issue by studying the relationship between morning commute congestion and urban form. The causes and consequences of traffic congestion have been extensively studied in the economics and engineering literatures. Unfortunately, most conclusions have been drawn from very idealized models, which either fail to consider adequately the spatial nature of congestion, by neglecting the effects of physical queues and merging interactions, or overlook dynamic aspects, such as commuters' departure time adaptation during the rush-hour. To better capture the spatial-dynamic nature of morning commute traffc, this dissertation proposes a new analytical framework that explicitly incorporates spatially distributed commuter origins,... https://escholarship.org/uc/item/6wk3t20s Wed, 12 Oct 2005 00:00:00 +0000 Lago, Alejandro https://escholarship.org/uc/item/5d69n86x This dissertation presents a vehicle reidentification algorithm for consecutive detector stations on a freeway, whereby a vehicle measurement made at a downstream detector station is matched with the vehicle’s corresponding measurement at an upstream station.&nbsp; The algorithm should improve freeway surveillance by measuring the actual vehicle travel times; these are simply the differences in the times that each (matched) vehicle arrives to the upstream and downstream stations.&nbsp; Thus, it will be possible to quantify conditions between widely spaced detector stations rather than assuming that the local conditions measured at a single station are representative of an extended link between stations. https://escholarship.org/uc/item/5d69n86x Wed, 12 Oct 2005 00:00:00 +0000 Coifman, Benjamin Andre https://escholarship.org/uc/item/55z3t7fh <p>Transit properties in the USA have historically experienced loss of market share and low levels of farebox recovery. They resorted to service expansion to maximize subsidies. Experience suggests that: (a) fare increases have not had the desired effect; (b) fare reductions can boost ridership but can also reduce revenue and increase subsidies. The challenge lies with the adoption of such strategies as deep discount group pass programs that can produce more marginal revenue than cost. Deep discount transit pass programs provide groups of people with unlimited-ride transit passes in exchange for a contractual payment for or on behalf of pass users by an employer or other organizing body. Although successes of deep discount group pass programs are documented, there is substantial skepticism toward their wide-scale deployment because transit management perceives them as "special treatments" or "favors" to participants. Management fears such perception could raise questions... https://escholarship.org/uc/item/55z3t7fh Wed, 12 Oct 2005 00:00:00 +0000 Nuworsoo, Cornelius Kofi https://escholarship.org/uc/item/4z3826fg <p>In Brazil, the recent explosion of informal transport activity is having profound effects on formal, regulated transport systems and is the source of great controversy in the urban passenger transportation arena. A variety of policies are being proposed to manage what has been an uncontrolled growth of the sector. This study seeks to understand the advantages these systems have for users who choose them, and how proposed policies will impact these benefits. A corridor in Rio de Janeiro with substantial informal activity was used as a case study and field trips were made to gather basic data and perform travel surveys. Standard measures of welfare changes in a discrete choice framework were used to measure the proposed policies' welfare impacts on users. Eleven candidate policies were evaluated, ranging from the eradication of the informal modes and investment in formal modes, to the legalization and regulation of the informal modes. Benefits were compared with costs to discuss... https://escholarship.org/uc/item/4z3826fg Wed, 12 Oct 2005 00:00:00 +0000 Golub, Aaron David https://escholarship.org/uc/item/4911j5zt <p>The objective of this research is to study the competition among ports. In particular we study the relation between port characteristics and port market share of maritime traffic. Maritime carriers make two primary decisions that affect ports. In the long-term, they assign vessels to routes. In the short-term, they assign each shipment to a vessel and, with that vessel, a port. In this research, we assume that vessel schedules are fixed and model the assignment of shipments as a function of the attributes that describe each port. For a carrier, some assignments are simpler than other assignments. Each assignment should, however, take into account the same criteria. We begin by examining the scheduling of vessels for its effect on the assignment of shipments. We measure the impact of being a vessel's first or last port of call on a port's market share, and we discuss factors that might influence these schedules. We then examine the assignment to ports for exports of various... https://escholarship.org/uc/item/4911j5zt Wed, 12 Oct 2005 00:00:00 +0000 Malchow, Matthew Brian https://escholarship.org/uc/item/2vk8w6nc <p>This dissertation presents dynamic stochastic optimization models for Air Traffic Flow Management (ATFM) that enables decisions to adapt to new information on evolving capacities of National Airspace System (NAS) resources. Uncertainty is represented by a set of capacity scenarios, each depicting a particular time-varying capacity profile of NAS resources. We use the concept of a scenario tree in which multiple scenarios are possible initially. Scenarios are eliminated as possibilities in a succession of branching points, until the specific scenario that will be realized on a particular day is known. Thus the scenario tree branching provides updated information on evolving scenarios, and allows ATFM decisions to be re-addressed and revised. First, we propose a dynamic stochastic model for a single airport ground holding problem (SAGHP) that can be used for planning Ground Delay Programs (GDPs) when there is uncertainty about future airport arrival capacities. Ground delays... https://escholarship.org/uc/item/2vk8w6nc Wed, 12 Oct 2005 00:00:00 +0000 Mukherjee, Avijit https://escholarship.org/uc/item/2g6850jc <p>Accurate facility deterioration models are important inputs for the selection of Infrastructure Maintenance, Repair, and Reconstruction (MR &amp; R) policies. Deterioration models are developed based on expert judgment or empirical observations. These resources, however, might not be sufficient to accurately represent the performance of infrastructure facilities. Incorrect deterioration models may lead to wrong predictions of infrastructure performance and selection of inappropriate MR &amp; R policies. This results in higher lifecycle costs. Existing infrastructure MR &amp; R decisionmaking models assume that deterioration models represent the real deterioration process of infrastructure facilities. This assumption ignores the uncertainty in empiricallyderived facility deterioration models. This dissertation presents a methodology for selecting MR &amp; R policies for systems of infrastructure facilities under uncertainty in the deterioration model parameters. It is assumed... https://escholarship.org/uc/item/2g6850jc Wed, 12 Oct 2005 00:00:00 +0000 Park, Sejung