ACADEMIC YEAR 2017–2018
Assessment of Contributing Factors to Air Service Loss in Small Communities
Stephanie Atallah and Susan L. Hotle
As indicated by current literature, service at small community airports was negatively affected by the Great Recession from 2007 to 2009 and recent changes in competition structure. Existing studies have looked at the recession’s lingering impact on small community airports (e.g., hub premiums, airport dominance, connectivity) and markets (e.g., market competition structure). However, to date it has been difficult to determine which factors contribute to a market’s potential future loss of service that serves a small community. In this study, we identified characteristics that could potentially contribute to a market’s loss or gain of service by incorporating different regional- and market-specific characteristics that have evolved over the years. This study used a fixed-effects conditional logistic regression and focused on region-to-region markets serving small communities that were in service at least once between 2007 and 2013. In total, the panel data included 1,367 markets departing from a small region and arriving at a small-, medium-, or large-sized region with 453 markets adding or losing service during that time. Fixed-effects were used to identify the impact of within-market variation on service loss over the years. Results showed that, first, markets affected by a merger were indeed at a higher risk of losing service. Second, markets operated by a fuel-intensive, small-aircraft fleet had a higher chance of being discontinued. Third, an increased number of competitors greatly reduced potential market service loss.
Design Process for Novel Concepts of Operation in Thin-Haul Aviation to Increase Airport Throughput
Raunak P. Bhattacharyya and Prof. Amy Pritchett
Traffic demand for many airports in the National Airspace System is predicted to eventually exceed their capacity. Thin-haul aviation has recently been proposed within NextGen with the potential for transforming mobility. However, achieving cost-effective, high-volume, and safe operations will require novel air traffic management concepts integrating these thin-haul aircraft into operations, particularly at small airports. This paper describes a process to design such air traffic concepts of operations. It first articulates the relevant design variables and constraints that impact the concept of operations, and then describes the considerations needed to traverse the design trade space. The process is demonstrated in a case study designing concepts of operations applying point merges and helical descents. The process includes both the design of the geometric airspace structures, and the actions that represent the work that needs to be done in the concept of operations. The contribution of this paper is establishing a starting point to guide operations designers in the wide design space that will be made possible under NextGen in general and thin-haul aviation in particular.
Development of Anti-Icing Airfield Heated Pavement System Using Solar Energy
Joseph Daniels and Ernest Heymsfield
This paper analyzes the development and assesses the viability of an anti-icing airfield heated pavement system using solar energy. Field experimentation investigates two systems: (i) an electrical heated pavement system with a photovoltaic energy system as its power source, and (ii) a hydronic heated pavement system with a solar water-heating system as its heating source. The systems operate under an automated thermostat heating sequence for operation optimization and energy conservation. Study results found the solar systems capable of supplying enough energy to maintain the pavement surface above freezing temperatures and keep it free of snow. A finite element model (FEM) was developed for the electrical system to assess the energy required to heat an airfield apron area. A benefit–cost analysis (BCA) expanded the hydronic system analysis to assess the viability for implementing a solar-hydronic heated pavement system at an apron area. The viability of an anti-icing airfield heated pavement system using solar energy was evaluated using a FEM analysis and BCA at an existing airport, the Northwest Arkansas Regional Airport.
Turning Maneuver Effect on Near-Surface Airfield Pavement Responses
Angeli Gamez and Imad L. Al-Qadi
Airport pavement structures experience heavy aircraft tire loading through a localized contact area. Distributed three-dimensionally and non-uniformly, tire-pavement contact stresses directly influence the near-surface behavior of flexible airfield pavements. The resulting high shear stress levels induced by aircraft tire loading may lead to instability through shoving or slippage cracking. As the tire turns during taxiing, the risk of near-surface damage is exacerbated. In this study, numerical modeling of an inverted pavement system and a conventional flexible pavement structure loaded with a single tire from the A-380 landing gear was developed. The analysis matrix included two tire-inflation pressures, two speeds, and rolling conditions that varied from free-rolling to two turning maneuvers. Two analysis approaches were performed: 1) use of traditional critical point strains, and 2) domain analysis, which characterizes bulk pavement behavior using multiaxial stresses and strains. The critical strains, which are used as inputs for airfield pavement design, changed negligibly under varying tire turning conditions despite the asymmetric contact stress distribution. On the other hand, domain analysis not only captured the asymmetric pavement behavior, but also identified that altering the tire movement from a free-rolling condition to turning could induce a significant increase in the potential damage.
Impact of State of Charge and Cell Arrangement on Thermal Runaway Propagation in Lithium Ion Battery Cell Arrays
Christopher Lee, Ahmed O. Said, and Stanislav I. Stoliarov
Lithium ion batteries are increasingly used in electrical energy storage systems despite their thermal and chemical hazards on failure. These hazards are magnified when multiple cells are combined together in a pack because of the risk of cascading failure. An experimental setup was utilized to investigate the dynamics, gaseous emissions, and energetics associated with thermal failure of cylindrical 18650 form factor, 2600 mAh, lithium cobalt oxide cathode cell arrays in an inert atmosphere. Cell state of charge (SOC) and arrangement were altered to investigate mitigation strategies and provide recommendations for safer battery pack design, transportation, and storage. Complete failure propagation was not prevented in any test, but decreasing to 50% SOC did result in propagation speeds 8.5 times slower than at 100% SOC. Introducing a 5 mm gap between cell rows also slowed propagation somewhat, but to a lesser degree than lowering SOC. Maximum temperatures, hazardous gas yields, and chemical heat generation were all reduced for cells at 50% SOC compared with 100% SOC, but introducing 5 mm gaps had little impact on these quantities. Limiting cells to 50% SOC was by far the most effective mitigation strategy tested, but no strategy was able to eliminate the failure propagation risk. Installing battery packs in inert environments, limiting SOC, and instituting gaps between certain cells can all be effective strategies to lessen the severity of cascading failure, but none of these strategies are individually sufficient for safe transportation and storage of battery packs.
Impact of Airline Mergers on Environmental Externalities
The U.S. airline industry has experienced consolidation in the last decade. At the same time, global environmental concerns have continued to grow. This paper examines the impact of three recent airline mergers on the environment by comparing per-departure NOX emission and the total NOX emission from merging firms at a given airport versus those emitted by non-merging firms at the same airport, by focusing on emissions from airplane flight landing/take-off cycles. The regression results suggest that mergers overall have no impact on either per-departure NOX emissions or total NOX emissions, while some individual mergers resulted in decreased emissions. However, this study finds that mergers have a negative impact on NOX emissions in the medium term when flight destinations are hub airports and a positive impact on NOX emissions in the medium term when flight destinations are non-hub airports.
Developing Large Slab Airport Runways for the Next Century
Stephen J. Roswurm and Chris Ramseyer
The purpose of this research was to determine whether shrinkage-compensating concrete (SCC) made with Type K cement can create durable airport runways with fewer joints and reduced maintenance costs. The primary criterion examined was the ability of SCC to offset the effects of early-age drying shrinkage when the concrete is acted upon by external restraint. The interaction of restraint with SCC is important because restraint resists the expansive behavior that provides shrinkage compensation. Four sets of experiments were conducted, with increasing levels of Type K expansive mineral additive in each set. A set of test specimens consisted of four-inch diameter restrained columns. Each set consisted of three columns with varying degrees of stiffness in the restraint frame, including low, medium, and high-restraint stiffness. The medium-restraint column provides the theoretical response of new pavement cast against a mature slab, whereas the other two bracket the problem. The column specimens were instrumented using vibrating wire strain gages, which were embedded in the concrete, and load cells, which were affixed to the top of the columns. This research concludes that SCC can be effective even with a stiff boundary condition, and that SCC provides the potential for much longer-lasting airport runway slabs, as a result of reduced shrinkage and therefore fewer cracks.
Iterative Framework for Performance and Environmental Impacts of Airfields
Izak M. Said and Imad L. Al-Qadi
The main goal of a durable and sustainable airfield is to withstand repeated aircraft traffic loading while minimizing the environmental impact. The objective of this study is to develop a design-life cycle assessment (LCA) framework considering a balanced evaluation of structural adequacy, minimizing emission, and optimizing total energy demand. To achieve this objective, three steps are introduced: an evaluation of the structural adequacy of the design using the Federal Aviation Administration (FAA) pavement design software FAA rigid and flexible iterative elastic layered design; a preliminary performance check using field instrumentation responses; and a LCA of airfield sections using both deterministic and probabilistic approaches. In addition to presenting the design-LCA methodology, this paper offers a comparative evaluation that covers two perpetual designs (LFP1-N and LFP4-N) and one conventional section (LFC5-N). These pavement sections were built and tested at the National Airport Pavement Test Facility as part of construction cycle 7, funded by the FAA. Responses collected from instrumentation were used to compute field-based coverages to failure. Moreover, life cycle inventories from secondary sources were used to quantify the greenhouse gas emissions and energy demand associated with the construction of these sections. Results show inconsistencies between the field-predicted and theoretically predicted performance. This suggests the need for the additional calibration of the currently used performance models. Moreover, this study shows that under a specific asphalt concrete (AC) thickness limit, conventional AC may be more eco-friendly than a perpetual design.
Impacts of Automated Vehicles on Airport Landside Terminal Planning, Design, and Operations
Yuan Wang and Yu Zhang
Income from parking, rental car facilities, and other ground access modes for most commercial airports in the United States is a significant component in revenue. With the emergence of automated vehicles (AVs), or so-called “self-driving vehicles,” these fundamentals could change. Airport stakeholders need to understand the impacts of the emerging AVs to airport planning, design, and operation. If the impact hurts the operational resilience and financial sustainability of the airports, the stakeholders should come up with countermeasures to alleviate the impacts and to ensure the smooth operation and continuous growth of the airport. To serve these needs, this study quantifies the potential impacts of AV on airport parking and ground access by building a simulation platform and applying scenario analyses. Two airports are selected for case study: Tampa, FL (TPA) and San Francisco, CA (SFO). To fill in the gaps of historical data, statistical methods are used to generate inputs for study airports based on historical information of passenger demand, ground access mode split, and parking categories and durations. Furthermore, future scenarios are developed based on reasonable assumptions of the emergence of AVs. Outcomes of the case study show that the emergence of AVs will significantly affect airport operation if nothing as of now was changed. However, the impacts could be different for airports that are more auto-dependent versus those in metropolitan areas with various ground access options. Moreover, this study discusses possible strategies that can help airports generate revenue in the era of emerging AVs.
Taxation in the Aviation Industry: Insights and Challenges
Quinton White, David R. Agrawal, and Jonathan W. Williams
Taxation in the aviation industry has evolved considerably over the last 25 years. Despite the vital role aviation and airports play in efficiently moving goods and people, the effect of taxation in this industry is understudied. Understanding how passengers and carriers respond to taxes and government fees is crucial to efficiently raising government revenue. After an overview of how taxation has evolved in the industry, this paper estimates how fares adjust in response to tax changes. Exploiting variation in taxes across similar routes and over time, the results suggest taxes are over-shifted to consumers (i.e., a $1 increase in taxes results in more than a $1 increase in the total fare). The paper discusses potential explanations for this result: the nature of competition in the industry and the propagation of taxes within a network.