# Vehicular Visible Light Communication for Intersection Management +
## 4 V2X Cooperative System Evaluation
### Traffic Signal Phasing: V2X Communication  
Based on the simulated traffic scenario (Figure 2) and utilizing V-VLC request/response messages, a phasing diagram was drawn, for functional areas with two-way-two-way four-legged (Figure 9a) and split (Figure 9b) intersections. Traffic volumes that arrive at the intersection are the same in both. Here, the traffic controller uses request and response messages, from vehicles \(a\), \(b\), \(c\), \(d\), \(e\) and \(f\), fusing the self-localizations \(q_{i}\) (\(t\)) with their space relative poses \(q_{ij}\) (\(t\)) to generate phase durations appropriate to accommodate the demand on each cycle. Each driving vehicle is assigned an individualized time to the request (\(t\)) to enter the intersection, and \(t[x]\) is the request time of vehicle \(x\) with their pose representations. Figure 8: Vehicle \(a\), \(b\), \(c\), and \(d\)’s normalized MUX signal responses and assigned decoded messages. On the top the transmitted channels packets [R, G, B, V] are decoded. (**a**) Four-legged intersection (out of the crossroad; vehicle \(a\), pose #2E, and vehicle \(b\), pose #7W). (**b**) Four-legged intersection; (inside the crossroad; vehicle \(c\), poses #7 NE, #1 NE). (**c**) Split intersection (out of the crossroads; vehicle \(a\), pose #2E, and vehicle \(b\), poses #6W). (**d**) Split intersection (crossroad 1; vehicle \(b\), pose #7W and #1 SW, and vehicle \(d\), before crossroad 1, poses #1E). Results show five different phases for the four-legged intersection: the pedestrian phase, Phase 1 (W straight flow), Phase 2 (W straight and left flows), Phase 3 (W and E left flows), and Phase 4 (N and S straight flows) as shown in Figure 9a. In Figure 9b, for the split intersection, the phasing flow for both crossroads are visualized: Intersection 1: Phases 0, pedestrian/bicyclist phase, Phase 1 (W straight flow), Phase 2 (W straight and left flows), Phase 3 (W and E left flows), and Phase 4 (N and right-turn approach flow). _t[x]_ is the request time of vehicle \(x\). Figure 9: Requested phasing of traffic flows: (**a**) Standard intersection; the pedestrian phase, Phase 1 (W straight flow), Phase 2 (W straight and left flows), Phase 3 (W and E left flows), and Phase 4 (N and S straight flows). (**b**) Split intersection: Intersection 1: Phase 0, pedestrian/bicyclist phase, Phase 1 (W straight flow), Phase 2 (W straight and left flows), Phase 3 (W and E left flows), and Phase 4 (N straight flow); Intersection 2: Phases 0, pedestrian/bicyclist phase, Phase 1 (W and east straight flows), and Phase 4 (S and right-turn approach flow). _t[x]_ is the request time of vehicle \(x\). flows), Phase 3 (W and E left flows), and Phase 4 (N straight flow); Intersection 2: Phases 0, pedestrian/bicyclist phase, Phase 1 (W and east straight flows), and Phase 4 (S and right-turn approach flow). The exclusive pedestrian and bicyclist stage, \"Walk\" interval begins in both at the end of Phase 5. From a capacity point of view, in a four-legged intersection, it is more efficient if vehicle \(c\) is given access at \({t^{\prime}}_{c}\) before vehicle \(b\), at \({t^{\prime}}_{b}\) to the intersection and vehicle \(d\) is given access at \({t^{\prime}}_{d}\) before vehicle \(e\), at \({t^{\prime}}_{e}\) then, forming a west left turn of set of vehicles (platoon) before giving way to the fourth phase (north and south conflicting flows), as stated in Figure 9a. The speed of vehicle \(e\) was reduced, keeping a safe distance between vehicle \(e\) and vehicle \(d\). So, vehicle \(b\) approaches the intersection after having asked permission to cross it and only receives authorization when the vehicle \(a\) has left the intersection (end of Phase 2). Then, Phase 3 begins with vehicle \(b\) heading to the intersection (W) (pose red) while vehicle \(a\) follows its destination towards E (pose green). In the split intersection, the conventional four-legged intersection was replaced by two separate intersections (Figure 9b).