# Assisting Drivers at Stop Signs in a Connected Vehicle Environment
## 1 Introduction  
Road intersections controlled by stop signs are commonly seen on road networks. At road intersections, several flows of traffic conflict with each other. Thus, accidents among vehicles are serious threats there. Several traffic techniques have been used to control safe and smooth mobility there, such as traffic lights, roundabouts, and stop signs [1]. These techniques are selected after carefully evaluating traffic conditions indicating their installation is warranted and appropriate. However, some road intersections do not need an official traffic control device, particularly in residential areas [2]. Driving laws have determined the right of way at road intersections based on their design and the road types on the intersection [3]. Stop signs are required to assign right of way at road intersections, not to control speed or efficiency. They are often used at intersections that are not busy enough to install a traffic signal or a roundabout. The need for stop signs involves a trade-off between safety and delay [4]. Stop signs have been required at road intersections when a less important road meets with the main road if there is a restricted view or a high accident record. Right-angle accidents can be reduced by the installation of stop signs when warranted. However,installing unrequired stop signs may increase rear-end accidents [5]. Stop signs are mainly installed on road intersections designed in T-junction or four-leg road intersections. In the T-junction design, the stop sign is usually installed on the secondary road that reaches the main straight road [6]. On the other hand, in four-leg road intersections, stop signs can be installed in all ways. This is when two main roads are at the intersection. However, if the four-leg road intersection contains main and secondary roads, the stop signs are installed at the two ways that belong to the secondary road [5]. In all scenarios, drivers must stop completely before the installed stop sign. After stopping at the road intersection controlled by stop signs, drivers have to follow the driving rules of that region to decide when to traverse the intersection. First to arrive, first to go, straight before turns, and right then left are the main driving rules for stopping vehicles at stop sign intersections [5]. Drivers must first be aware of the stop sign's existence, then the architecture of the signalized road intersection, and the traffic distribution of the competing traffic flow at that intersection. This is to decide when or how long to wait to pass the intersection. Due to bad weather conditions, obstacles, or heavy existing vehicles, drivers may miss seeing the stop sign. Moreover, the architecture of the road intersection and the characteristics of the competing traffic flows are not always clear to the drivers. Drivers may unsafely pass through the intersection because of the lack of knowledge regarding the type of road intersection or the competing traffic characteristics. In this work, first, we aim to notify the driver of the existing stop signs at the next road intersection in case the driver misses the notification. The design of the road intersection and the real-time traffic characteristics of the competing traffic flows at the intersection are also reported to drivers there. Then, according to the driving rules and the traffic characteristics of the competing traffic flows at the intersection, the best driving behaviors (e.g., stop, move, decrease speed, or increase the speed) are determined and recommended to each vehicle that aims to pass through the intersection. The technology of vehicular ad-hoc networks (VANETs) is used to gather the traffic characteristics over the investigated area of interest. Vehicles are equipped with wireless transceivers that periodically transmit the basic traffic data of the vehicle. The traffic characteristics and context of each traffic flow at the intersection are evaluated internally in each vehicle based on the received messages from the neighboring vehicles.