This paper analyzes the effects traffic flow controllers, such as stop signs and stop lights, have on the flow of traffic through a 4-way intersection. In particular, we investigate which controller (either using 2 stop signs, 4 stop signs, or stop lights) to use depending on the number of cars in a lane. We use a method that accounts for a set number of cars in each lane and a car’s velocity based on the distance to the stop line or to the car in front. We also account for how a car will turn once it reaches the stop line. When a car stops at an intersection, we change our model depending on the traffic flow controller being used. With stop signs, a car must first stop and can only proceed when certain cars have cleared the intersection. With lights, a car must wait for the appropriate light to turn green before the car can continue moving. In the end, we found it best to use 2 stop signs when there are less than 20 cars in each lane, stop lights when there are more than 30 cars in each lane, and 4 stop signs otherwise.