# Smart Road Traffic Accidents Reduction Strategy Based on Intelligent Transportation Systems (TARS)
## 2 Literature Review
### Traffic Accident Avoidance and Prevention Based on Warning Messages  
[PERSON] et al. [16] proposed the warning message scheme to avoid traffic accidents between vehicles by sending a warning message to alert drivers about the condition of the current accident. The proposed scheme used the distance-based flooding scheme. The author calculated the time of the vehicle's reaction after the occurrence of the accident in order to prevent further traffic accidents. Furthermore, a warning message dissemination scheme has been introduced for low priority messages in order to achieve efficient bandwidth utilization. The proposed routing scheme achieved the best high and low priority message dissemination in drastic weather conditions, i.e., rain, sun, etc. Furthermore, the routing scheme achieved less delay and an efficient utilization of the bandwidth under different traffic conditions. However, the limitation of this routing scheme is that it does not work in a highly dense vehicular environment. Another limitation of this scheme is the highest priority message that the author used in the simple flooding scheme. So, the time utilized in taking the forwarding decision was less. Therefore, the proposed scheme faces scalability issues related to the dissemination of high priority messages. [PERSON] et al. [17] proposed an accident avoidance routing scheme named Road Accident Prevention (RAP). This scheme introduced the Early Warning (EW) message in order to make essential decisions--selecting alternate routes, slowing down the vehicle, and changing lanes. Furthermore, the Road Side Unit (RSU) detects any unusual activity in the highway scenario and broadcasts an Early Warning (EW) message to all the vehicles in the range of the RSU. In this way, the EW message must be sent at the exact time to prevent the road accident. The authors introduced different types of risk zone, namely, high, average, and low risk zones. The high-risk zone comprises those vehicles that are nearest to vehicles that are involved in road accidents. The routing scheme successfully achieved less delay. However, the limitation of the proposed scheme was the high network processing overhead due to the extra warning message transmitted, the EW message and identification of the risk zone. [PERSON] et al. [18] proposed an accident avoidance scheme named the Efficient Emergency Message Broadcasting (EEMB) routing scheme. The objective of the proposed scheme was to reduce traffic bottlenecks and prevent multiple road accidents by broadcasting emergency messages with low overheads at high velocity. After an accident has occurred between two vehicles, the affected vehicle will select the best forwarder and broadcast the emergency message until the emergency message covers the whole risk zone. The forwarding scheme achieved the minimal overhead caused by the beacon message by using the method of the early prediction system. The beauty of this forwarding scheme is that it overcomes the problem of network fragmentation by using the mechanisms of store-carry and forward. [PERSON] et al. [19] considered that the consumer with the emergency message must disseminate the message intermittently until it selects another forwarder vehicle. However, this dissemination causes a duplication of the broadcasting message due to multiple broadcasting attempts that do not help the vehicle to obtain another vehicle. Therefore, the network of the traffic will be affected from the processing overhead. In order to minimize the processing overhead, the author proposed a scheme named Optimized Dissemination of Alarm Message (ODAM) while restricting the regions and forwarder vehicles. The ODAM routing scheme efficiently achieves less overhead due to the periodical broadcasting message. However, the ODAM scheme experiences a high delay by sending the emergency messages to the forwarder vehicle. [PERSON] et al. [20] proposed accident avoidance and congestion prevention in a vehicular environment. In this scheme, after the accident occurs, the affected vehicle generates the emergency message.