# Discussion on the Design of Sprayed Eco-Protection for Near-Slope Roads Along Multi-Level Slopes
## 1 Introduction  
Over the past three decades, ecological slope protection technologies have evolved into a diverse array of methods. Among these, sprayed eco-protection technology has emerged as the dominant approach due to its safety, efficiency, high mechanization, and cost-effectiveness, making it the preferred choice for large-scale, cost-sensitive, and efficiency-sensitive multi-level slope remediation. Near-slope roads for multi-level slopes refer to temporary roads adjacent to slope faces, serving both excavation and subsequent eco-protection construction [1, 2]. While technology has maturered in construction techniques, machinery, and evaluation methods after decades of application, improper design of near-slope roads remains a critical issue in multi-level slope projects. This is largely attributable to the lack of integrated planning between excavation and ecological restoration phases, which are often handled by separate design entities. Multi-level slopes are widely found in construction projects such as highways, water conservancy and hydropower facilities, residential buildings, mines, and ports [3]. Platforms on these slopes intercept and accumulate rolling debris, thereby mitigating safety risks associated with falling objects. Beyond this safety function, some platforms serve as pathways for excavation equipment and pedestrians, known as berms [4]. To fulfill traffic requirements, berms at each slope level connect to mixing sites via near-slope roads,collectively forming a temporary road system [5, 6]. Designing this system represents a fundamental cross-industry engineering challenge, as most excavated multi-level slopes require stabilization enhancement and ecological restoration [7, 8, 9]. A significant complicating factor is that excavation design and ecological restoration design are frequently undertaken by different specialized companies, resulting in fragmented responsibility and inconsistent standards for near-slope road planning. Currently, China lacks comprehensive guidelines for designing temporary road systems on multi-level slopes. For instance, the Technical Code for Building Slope Engineering covers only single-level slope design requirements, excluding multi-level slopes and their associated temporary roads. Although the Technical Standard for Highway Engineering provides some design parameters for temporary roads on multi-level slopes, its applicability is limited by insufficient consideration of operational constraints for medium and large vehicles (e.g., water trucks, hydroseeders, excavators), which leads to unreasonable parameters such as the radius and width of the terms [10]. Internationally, while standards such as Hong Kong's Geotechnical Manual for Slopes (GEO Publication No. 1/2023) address temporary access roads in slope works, they primarily focus on safety protocols rather than integrated design methodologies for multi-level systems [11]. Similarly, the US Mine Safety and Health Administration (MSHA) regulations mandate temporary road specifications for mining benches but lack provisions for ecological restoration phases [12]. The EU Directive on Management of Waste from Extractive Industries (2006/21/EC) emphasizes slope stability yet omits standardized temporary road design for multi-tier remediation [13]. The disconnect between excavation and eco-restoration designers further compounds these challenges globally, since near-slope road requirements often fall outside their respective scopes. Consequently, engineers face significant difficulties when designing this system due to the fragmented regulatory landscape. To meet the traffic needs of multi-level slopes during both the excavation and ecological restoration phases, this paper first proposes the overall design steps and detailed methods for road-related parameters, including planar layouts, widths, gradients, and minimum curve radii. The proposed approach is then applied to the multi-level slopes in the Huamahu Airport project, followed by a comparative analysis between the new design and the original scheme.