## 1 Introduction  
### Research Background  
In urban road traffic networks, intersections are the most fundamental nodal elements and can easily become traffic bottlenecks. With the rapid increase in urban traffic motorization levels and continuous growth in traffic demand, intersection congestion problems have become increasingly prominent. Even in congested conditions, intersections still contain a large amount of time and space resources that are not effectively utilized. The essential and structural reason is that traditional static intersection lane design methods and schemes (fixed lane functions, lateral arrangement of lane functions, etc.) struggle to adapt to dynamic changes in traffic demand (volume and direction) and the requirements for turning or U-turn traffic conditions, thus limiting the performance and effective enhancement of urban road intersection efficiency [1]. The fundamental limitations of deterministic conventional lane configurations manifest in two critical dimensions. Spatially, fixed lane boundaries create rigid resource allocation that cannot respond to directional demand imbalances, resulting in systematic underutilization where certain movements experience excess capacity while others become oversaturated. Temporally, predetermined signal phases operate independently of real-time traffic fluctuations, leading to inefficient green time distribution and poor demand-supply matching. Non-conventional lanes overcome these limitations through dual-axis flexibility mechanisms. Spatial flexibility includes dynamic space borrowing, adaptive function conversion, and position optimization. Temporal flexibility encompasses real-time switching protocols, coordinated multi-signal control, and demand-responsive timing optimization. This dual-axis approach aligns with contemporary urban traffic management policies emphasizing infrastructure efficiency maximization, safety enhancement, and environmental sustainability. To address previous issues in intersection lane configuration, various non-conventional lane arrangements have been adopted in practice at intersection approaches and exits, including contraflow left-turn lanes, outside left-turn lanes, left-positioned right-turn lanes, various U-turn lanes, and variable lanes. These non-conventional design methods provide new approaches to solving traffic congestion problems by altering the traditional \"left-straight-right\" static layout. Evidently, the introduction of non-conventional lanes has changed the previous intersection traffic patterns and the spatiotemporal coordination of right-of-way, providing important support for refined urban traffic management [2]. However, as the application and promotion of non-conventional lanes has outpaced theoretical research progress, further improvements are needed to support high-quality urban traffic development. The introduction of non-conventional lanes not only reconstructs motorized vehicle traffic rules but also changes the right-of-way allocation for non-motorized vehicles and pedestrians, fundamentally altering the relationships among mixed traffic flows within intersections. This change involves multiple dimensions: in the spatial dimension, the longitudinal and lateral matching of approaches and exits and the organization of lane function conversions; in the temporal dimension, signal timing optimization and traffic order reconstruction; and in the safety dimension, traffic conflict identification and management. [PERSON] and [PERSON] [3] defined non-conventional intersection design as \"innovative design methods that more effectively utilize road space and improve intersection capacity by changing traditional geometric layouts and traffic organization methods.\" [PERSON] and [PERSON] [4] systematically expounded the principles and key technologies of traffic design in their textbook _\"Traffic Design,\"_ providing a theoretical foundation for non-conventional intersection design, namely, under what conditions (when and where) should a certain non-conventional lane be established?