Vehicle traffic congestion leads to air pollution, driver frustration, and costs billions of dollars annually in fuel consumption. Finding a proper solution to vehicle congestion is a considerable challenge due to the dynamic and unpredictable nature of the network topology of vehicular environments, especially in urban areas. Instead of using static algorithms, e.g. Dijkstra and A*, we present a bio-inspired algorithm, food search behavior of ants, which is a promising way of solving traffic congestion in vehicular networks. We have called this the Antbased Vehicle Congestion Avoidance System (AVCAS). AVCAS combines the average travel speed prediction of traffic on roads with map segmentation to reduce congestion as much as possible by finding the least congested shortest paths in order to avoid congestion instead of recovering from it. AVCAS collects real-time traffic data from vehicles and road side units to predict the average travel speed of roads traffic. It utilizes this information to perform an ant-based algorithm on a segmented map resulting in avoidance of congestion. Simulation results conducted on various vehicle densities show that the proposed system outperforms the existing systems in terms of average travel time, which decreased by an average of 11.5%, and average travel speed which increased by an average of 13%. In addition, AVCAS handles accident conditions in a more efficient way and decreases congestion by using alternative paths.

Recently, vehicular ad hoc networks (VANETs) have received more attention in both academic and industry settings. One of the challenging issues in this domain is routing protocols. VANETs' unique characteristics such as high mobility with the constraint of road topology, fast network topology changes, frequently disconnected networks, and time-sensitive data exchange makes it difficult to design an efficient routing protocol for routing data in vehicle-to-vehicle (V2V) and vehicle-toinfrastructure communications. Designing routing protocols for V2V commutations are more challenging due to the absence of infrastructure nodes in the communication procedure. They become even more challenging, when they get benefit from dynamic anchor computation method in which the anchor nodes (junctions or basic nodes for routing) are dynamic in their routing procedure. Positionbased routing protocols have been proven to be superior and outperform the other protocols since there is no requirement to establish and save a route between source and destination during the routing process which is suitable for dynamic nature of vehicular networks. In this paper, the performance of V2V dynamic anchor position-based routing protocols, which are proposed for the most challenging condition of packet routing in VANET, are investigated and evaluated under two different scenarios (i.e. various vehicle densities and velocities) through NS-2. The obtained results are then illustrated based on average delay, packet delivery ratio and routing overhead as routing performance indicators. Our objective is to provide a quantitative assessment of the applicability of these protocols in different vehicular scenarios. The comparison provided in this paper makes the research contribution of this survey paper quite higher than a regular survey paper only with explanations.Keywords Vehicular ad hoc networks Á Position-based routing Á Anchor-based Á Vehicle-to-vehicle

Variable speed limits (VSLs) as a mean for enhancing road traffic safety are studied for decades to modify the speed limit based on the prevailing road circumstances. In this study the pros and cons of VSL systems and their effects on traffic controlling efficiency are summarized. Despite the potential effectiveness of utilizing VSLs, we have witnessed that the effectiveness of this system is impacted by factors such as VSL control strategy used and the level of driver compliance. Hence, the proposed approach called Intelligent Advisory Speed Limit Dedication (IASLD) as the novel VSL control strategy which considers the driver compliance aims to improve the traffic flow and occupancy of vehicles in addition to amelioration of vehicle's travel times. The IASLD provides the advisory speed limit for each vehicle exclusively based on the vehicle's characteristics including the vehicle type, size, and safety capabilities as well as traffic and weather conditions. The proposed approach takes advantage of vehicular ad hoc network (VANET) to accelerate its performance, in the way that simulation results demonstrate the reduction of incident detection time up to 31.2% in comparison with traditional VSL strategy. The simulation results similarly indicate the improvement of traffic flow efficiency, occupancy, and travel time in different conditions.

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