## 2 Concepts, Forms, and Classification of Non-Conventional Lanes  
### Concept Definition and Development History  
Non-conventional lanes are defined in contrast to traditional \"left-straight-right\" conventional lane configurations, with the core characteristic of allowing dynamic changes in lane function or direction to adapt to traffic conditions. [PERSON] et al. [8], in their study of non-conventional lane design, pointed out that these innovative designs primarily improve intersection capacity by changing traditional geometric layouts and traffic organization methods. Specifically, non-conventional lanes achieve the reallocation of intersection time-space resources by breaking through traditional space utilization patterns. From a spatial dimension, non-conventional lanes break the fixed layout of traditional lane functions, allowing dynamic adjustments of lane functions at different time periods; from a temporal dimension, through refined management of signal control, they achieve a flexible allocation of right-of-way among different traffic participants. Conventional lane design is based on deterministic principles, where vehicles cannot interchange between approach and exit lanes, and lane functions are fixed at the initial design stage. This static approach, while providing standardized design protocols, exhibits critical inflexibility in spatiotemporal resource utilization. The deterministic framework prevents dynamic adaptation to varying traffic demands and fails to capitalize on available time-space resources during off-peak periods or directional imbalances. In contrast,non-conventional lanes introduce adaptive capacity through spatiotemporal reconfiguration, enabling intersections to respond dynamically to changing demand patterns while maintaining operational safety and efficiency. While this static traffic organization method provides unified design standards, it lacks flexibility, cannot fully utilize intersection time-space resources, and struggles to respond to the demands of dynamic traffic flow. The introduction of non-conventional lanes changes the previous intersection traffic patterns and spatiotemporal coordination of right-of-way relationships, enabling intersections to better adapt to dynamic changes in traffic demand. Non-conventional lanes achieve spatiotemporal transformation through three mechanisms: spatial reconfiguration (dynamic space borrowing and position shifting), temporal flexibility (coordinated signal control), and flow reorganization (optimized movement patterns). Unlike conventional static layouts, these designs enable dynamic resource reallocation. For example, contraflow left-turn lanes transform opposing exit space into left-turn capacity during specific signal phases, while variable lanes convert fixed functions into demand-responsive resources. In connected and automated vehicle environments, precise trajectory control and vehicle-infrastructure communication further enhance these benefits through seamless transitions and predictive optimization, transforming non-conventional lanes from passive infrastructure into active traffic management systems. Each development phase demonstrates distinct technological innovations and operational characteristics. The exploration period (late 20 th century) focused on basic reversible lane concepts using mechanical control systems and manual operation, primarily addressing morning and evening peak hour directional imbalances. The rapid development period (early 21 st century) introduced diverse forms, including contraflow left-turn lanes, outside left-turn lanes, and tandem intersections, supported by electronic signal control, pre-signal coordination, and computer-based optimization methods. Key technological advances included mixed-integer programming models for design optimization, cellular automata simulation for operational analysis, and refined traffic flow theory applications.