# Hub Airport End-Around Taxiway Construction Planning Development: A Review
## 6 Conclusions  
End-around taxiways exist primarily for the purpose of minimizing runway crossings. In the early stages of construction, the absence of relevant rules led to significant variations in their configuration, layout, and taxiing length, subsequently leading to varying operational efficiency. Additionally, with growing congestion on the runway, EATs can reduce the runway occupation time, making it meaningful for enhancing runway capacity. Furthermore, the safety benefits brought by EATs are undeniable.  
It is concluded that:  
* The key to improving end-around taxiway efficiency is reducing their physical length, mainly determined by the distance from the end-around taxiways to the runway end or threshold. With careful planning, the distance between EATs and runway ends can be optimized, leading to shorter taxiing distances, reduced land usage and investment, and the achievement of both safety and efficiency objectives.
* In designing the end-around taxiway, it is crucial to initially establish the operation mode, taking into account the airport's land use and the specific runway configuration, whether it pertains to BAT, REAT, or SAT.
* The minimum distance from BAT to the end of the runway or the runway threshold is 350-385 m. The design of REAT is mainly determined by the 2% climb surface, visual obstacles, and the requirements for approach lighting settings. SAT is a fully functional end-around taxiway with the most flexible usage, but it requires the farthest distance from the end or threshold. The factors involved in SAT design are the most intricate.
* By appropriately utilizing the original terrain differences and adopting methods such as sunken EATs and relocated runway entrances, the taxiing distance can be reduced while ensuring both safety and efficiency.
* It is advisable for hub airports to allocate space for the construction of EATs during the planning of their master plan.  
This study was limited to reviewing the existing advancements in end-around taxiway research. Due to the constrained scope, a comparative technical and economic analysis of different end-around taxiway operation modes, including BAT, REAT, and SAT, was not undertaken. However, determining the suitable end-around taxiway type and utilization strategy is an essential component of end-around taxiway design.  
Conceptualization, X.J.; formal analysis, X.J. and P.H.; resources, X.J.; data curation, [PERSON]; writing--original draft preparation, [PERSON]; writing--review and editing, [PERSON]; visualization, [PERSON]; supervision, [PERSON]; project administration, [PERSON]; funding acquisition, [PERSON] All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
The authors would like to thank [PERSON] and [PERSON], as they provided great assistance in the airport informaton collection process and Language help.  
Author [PERSON] was employed by the company China Airport Planning & Design Institute Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.