# Smart Road Traffic Accidents Reduction Strategy Based on Intelligent Transportation Systems (TARS)
## 3 Smart Road Traffic Accidents Reduction Strategy
### Phases of Traffic Accidents Reduction Strategy (TARS)
#### Execution Phase  
The TARS focuses on the use of the distance measurement approach for warning message generation to prevent accidents along with the efficient rerouting of traffic. An illustration of the proposed technique is shown in Figure 3. The RSU broadcasts the beacon message containing its identity and location in its range so that vehicles moving in its vicinity can communicate with it. The vehicle broadcasts the Basic Safety Message (BSM) to the RSU when it listens to the beacon message of a RSU. The BSM consists of the vehicle id (Vehicle-ID), location, speed, and direction. The RSU maintains a map between the vehicle identity and location of each vehicle moving in its range. The RSU adds the information about a vehicle according to the latest BSM received from a vehicle. Vehicles then broadcast the BSM every \(t\) milliseconds. The RSU updates the record at the reception of each BSM. If a distance between the two vehicles, moving on same road lane, is less than the safe distance (\(D_{v}\)) then the leading vehicle sends warning message to the following vehicle. On the other hand, the RSU also monitors the distance (D) and velocity (Velocity\({}_{i}\)) of each vehicle. It sends a warning message to warn that vehicle. \(D_{v}\) is calculated using the method presented in Section 3.4. Whenever the distance between the two vehicles is less than \(D_{v}\), the RSU sends a warning message to the following vehicle to keep the safe distance. If in a certain time period (\(T_{p}\)), the RSU has sent \(T_{alert}\) messages, then it means there is a high traffic load in that area. The values considered for \(T_{p}\) and \(T_{alert}\) were 10 s and 4, respectively. These values were taken from [34]. Afterwards, the RSU sends a high traffic congestion message to the previous neighboring RSU to reroute the traffic. The neighboring RSU will reroute the upcoming vehicles as shown in Algorithm 1. In case vehicles are moving outside the range of the RSU, and the distance between the two vehicles becomes less than \(D_{v}\) at some time, the leading vehicle sends a warning message to the following vehicle to keep a safe distance. Meanwhile, it also reports it to the previously connected RSU through neighboring vehicles. Neighboring vehicles only act as relay nodes and they pass on the message to the trailing vehicles until it reaches that particular RSU. Figure 2: Authorization Phase. * [1]**Input**:BSM
* [2]**RSU extracts VID;
* [3]**VID** is _registered_ **then**
* [4]**Calculate Tsi;
* [5]**Calculate D\({}_{i}\);
* [6]**if TS: _exjred_ **then**
* [7]**Wait for 10 secs;
* [8]**if BSM _received_ **then**
* [9]**Go to the line Calculate TS\({}_{i}\)
* [10]**else**
* [11]**Delete Vehicle-ID;
* [12]**else**
* [13]**else**
* [14]**Vehicle monitors Velocity;
* [15]**if Velocity \(<\)D; **then**
* [16]**Wait for some period;
* [17]**if Velocity \(<\)D\({}_{i}\)then**
* [18]**RSU sends warning message to vehicle to keep the safe distance;
* [19]**Wait for Tp;
* [20]**Congestion message and increment = 0;
* [21]**else**
* [22]**Go to the line Vehicle monitors Velocity;
* [23]**if After certain T\({}_{i}\), RSU sent Talerf\({}_{i}\)then**
* [24]**Detect high traffic load in the area;
* [25]**Increment + 1;
* [26]**else**
* [27]**Do Nothing:**
* [28]**if increment \(>\)= Talert then**
* [29]**Send congestion alert message to the previous RSU to reroute the upcoming traffic;
* [30]**else**
* [31]**Wait for Congestion End Message;
* [32]**else**
* [33]**Go to the line Vehicle monitors Velocity;
* [34]**else**
* [35]**send to TA;
* [36]**if**VID _is registered_ **then**
* [37]**Send Verification Message to RSU;
* [38]**Go to the line Calculate TS\({}_{i}\);
* [39]**else**
* [40]**Contact to GA;**  
A flowchart of the methodology of the proposed strategy is shown in Figure 4.  
Figure 3: Illustration of Traffic Accidents Reduction Strategy (TARS). Figure 4: Workflow of TARS.