# Hub Airport End-Around Taxiway Construction Planning Development: A Review
## 4 The Construction Principles and Key Points of End-Around Taxiway Layout
### Limiting Requirements in End-Around Taxivany Design  
In this section, we outline the fundamental considerations for EAT planning and design, drawing on real-world construction expertise and EAT categorization. Recognizing the intricate nature of EAT design with its array of requirements, this article puts forth a succinct synthesis of salient points, intending to provide planners and designers worldwide with an indispensable reference.  
The N-type, M-type, and large N-type classification of EATs relates to runway and terminal layout, which is beyond this paper's scope. Therefore, this article focuses on summarizing the key design considerations for SAT, REAT, and BAT classifications.  
Table 5 demonstrates the Limiting Requirements of BAT, REAT, and SAT end-around taxiways. Flight procedures encompass the horizontal paths and vertical profiles of all stages of aircraft approach and departure. It is a crucial factor to consider in the design of EATs. Flight procedure design takes into account airport topography, airspace, navigation facilities, and relevant regulations. Presently, there are two main internationally recognized flight procedure design specifications: ICAO DOC8168 [75] and the FAA Order 8260.3 F (TERPS) or Order 8260.58 C. As mentioned earlier, the FAA has already provided a comprehensive summary of EAT limiting factors under TERPS. This study is based on the research conducted using the 6 th Edition of DOC8168 [75], focusing specifically on the EAT design for SAT, REAT, and BAT modes within Category I, II, and III precision approaches in flight zones with aerodrome reference code number 3 or 4 [70].  
Please note that the planning of EAT is complex. This article only focuses on the impact of taxiways on the runway that aircraft may go around. However, it is important to note that if the distance between parallel runways is close (approximately 300 m), the EAT can also affect both runways. Due to the limited scope of this article, this aspect will not be discussed in further detail, but it is crucial for planners to take this factor into account.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Limiting Requirements** & **BAT** & **REAT** & **SAT** \\ \hline \multirow{4}{*}{\
\begin{tabular}{c} Appendix 14 Obstacle \\ Limitation Surfaces \\ (ILS Surfaces) \\ \end{tabular} } & Clearance Zone (Runway strips/Inner Transitional, & & \\  & Inner Approach, Balked Landing surface) & \(\surd\) & \(\surd\) \\ \cline{2-4}  & Take-off Climb Surface & \(\surd\) & \(\surd\) \\ \cline{2-4}  & Approach Surface & & \(\surd\) \\ \hline \multirow{4}{*}{
\begin{tabular}{c} Flight Procedures and \\ Aircraft Performance \\ Restriction \\ \end{tabular} } & Obstacle Assessment Surface (OAS)/Collision Risk & & & \(\surd\) \\ \cline{2-4}  & Visual Segment Surface (VSS) & & & \(\surd\) \\ \cline{2-4}  & Navigation Facilities & \(\surd\) & \(\surd\) \\ \cline{2-4}  & Lighting Facilities & \(\surd\) & \(\surd\) & \(\surd\) \\ \cline{2-4}  & Visual Obstruction & & \(\surd\) & \\ \cline{2-4}  & Jet Blast Effect & \(\surd\) & & \(\surd\) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Limiting requirements of BAT, REAT, and SAT end-around taxiways.