# A Systematic Literature Review of Autonomous and Connected Vehicles in Traffic Management
## 3 Research Analysis
### Traffic Management Methodologies Consisiting of Primary Goals
#### 3.2.3 Safety and Efficiency
A hybrid centralized/distributed architecture was also created by [65] to coordinate AVs and enable vehicles to cross crossings safely and quickly. The design employs a decentralized technique to prevent collisions and a centralized way to set the crossing duration with the maximum speed. The authors developed the reserve advance, act later (RAAL) and high-QoS-in-prior strategies [29] to accomplish these objectives. In the same spirit, authors modeled and constructed a standard cooperation mechanism for AVs to aid them in safely passing junctions. Another study [30] suggested a model to arrange the AVs at the junction based on the production line approach to prevent collisions and shorten wait times. They also used the K-Nearest Neighbors (KNN) method to anticipate how vehicles would proceed in a right turn. The simulation results show that the suggested model is more efficient for average and random traffic flow than the current paradigm. Reference [100] suggested a heuristic method to prevent space-time conflicts at the junction while considering the delay. Additionally, reference [101] developed an MPC-based central supervisory controller. The simulation results show that the recommended method beats the FCFS policy and traditional traffic lights in terms of transient reaction time and average delay. Another study [102] presented a distributed dispute resolution method using V2V communication to let CAVs traverse the signalized or unsignalized junction safely and effectively. Their study's findings suggested that by reducing the average wait time, the proposed strategy would increase intersection efficiency. Reference [103] suggested an intersection coordination method based on mixed-integer programming to ensure safe and effective traffic flow in junctions (MICA). The proposed technique outperforms the optimal traffic-light mechanism and the trajectory-based intersection traffic coordination algorithm [96] in terms of traffic flow, according to the simulation results. By expanding the conventional single collision-set (CS) method, ref. [66] presented multiple-collision-set solutions to increase traffic throughput. According to the numerical findings, the suggested system might offer safe and effective traffic coordination. To manage the junction and coordinate vehicles, ref. [104] presented a collision-aware resource allocation (CARA) technique based on a self-triggered approach. Additionally, ref. [67] suggested a dynamic coordinating framework based on the queuing theory to enhance the quality of service (QoS). The theoretical analysis and simulation results show that the recommended strategy can guarantee road stability and deliver high QoS. To increase junction efficiency and decrease traffic accidents, ref. [105] presented a game-in-game structure. The simulation results suggested that the framework may reduce accidents and boost productivity. Reference [106] put out a fresh approach using the evolutionary algorithm to improve intersection throughput automatically. To offer a realistic simulation environment, a cellular automata simulator was created. According to the simulation results, the suggested approach can increase throughput compared to the conventional method by 9.21-36.98%. A distributed management system to manage junctions was presented by [68] as a solution to the drawbacks of centralized traffic management systems. The simulation results demonstrated that the suggested solution performs better throughput than a traditional traffic control system. Similarly, ref. [107] proposed a method based on trajectory planning for autonomous intersection management (TP-AIM) to establish an accident trajectory and give priority and course to vehicles by assuming delay to increase the safety and efficiency of an unsignalized intersection. As a result, the throughput increases by more than 20%, while the average evacuation time is minimized. Additionally, the junction delay is decreased to less than 10% compared to the standard traffic signal.