# Hub Airport End-Around Taxiway Construction Planning Development: A Review
###### Abstract  
Hub airports typically have multiple parallel runways, requiring aircraft to transfer between them. This increases the risk of runway incursions. End-around taxiways (EATs) mitigate such risk by enabling bypassing without runway crossings. This review summarizes 15 EAT layouts worldwide and presents two classification methods: by configuration (N-type, M-type, Large N-type) and by operational relationship with runways (back-around, runway end-around, start-around). The key benefits of EATs were manifold, including the reduction of runway incursions, controller workload, and delays while improving communication safety, capacity, and efficiency. However, drawbacks such as increased land use, construction costs, and potentially longer taxi times and distances should be considered. Therefore, the optimization of the EAT layout is essential. In pursuit of optimal design, considerations should encompass limiting obstacle surfaces, flight procedures, navigation/lighting facilities, jet blast, and visual obstructions from end-around aircraft to departing aircraft. Notably, challenges arise in reducing distances between EATs and thresholds/ends. The given solutions include displacing thresholds, creating \"sunken\" lowered elevation EATs, and utilizing terrain shielding instead of metallic visual screens. A case study was introduced to demonstrate the successful improvement of the EAT via sunken EATs and terrain shielding at Guiyang Airport. The conclusion encourages further optimization of EAT layouts that balance safety and efficiency. end-around taxiway (EAT); parallel runway; taxiway layout; runway incursion; taxiing time; design consideration; sunken taxiway; terrain shielding +
Footnote †: journal: Medical  
Previous studies have suggested that the implementation of EATs could enhance airport safety by eliminating runway crossings [4]. EATs have two primary impacts on airport efficiency. While they theoretically enhance runway capacity by reducing runway occupancy times, actual capacity gains depend on operational factors like arrival and departure intervals [5]. Studies on airports like DFW, ATL, and DTW show significant variations in actual taxi times with EATs compared to conventional taxiing [6; 7]. Excessively long travel distances inflate taxi times, while substantial land use and construction costs add concerns. Consequently, after initial projects, major US and European hubs paused EAT development in the late 1900s, with some master plans deferring proposals [8]. However, recent brisk aviation growth in certain markets like China renews the impetus for EAT construction. The increase in runway incursions from runway crossings has prompted airport planners to reconsider EATs [9; 10; 11]. The Federal Aviation Administration (FAA) awarded grants of more than $1.0 billion for more safety projects under the Airport Improvement Program. These projects include new plans to construct new taxiways to enhance safety on the airfield [12]. This study aims to inspire airport operators and researchers to explore innovative planning and construction methods for EATs in the future. * The primary objective of this study is to comprehensively summarize the construction and operational status of end-around taxiways across the globe. We categorize existing end-around taxiway layouts, summarize the benefits of those in operation, and highlight their contributions to enhancing airport safety and runway operational efficiency. Furthermore, we delve into the recognized limitations of end-around taxiways, including increased land utilization, construction costs, and potential decrements in taxiing efficiency, drawing insights from the operational experiences of airports equipped with such taxiways. * Moreover, the study aims to propose refined design methodologies for end-around taxiways. We outline the key design considerations and factors for end-around taxiway designs in diverse operational modes, with a particular focus on minimizing the lengths of end-around taxiways (EATs).