It is a fact that traffic lights are seldom managed optimally when preemptive vehicles are allowed. More and more attention has been given to these problems, often with a practical perspective. It is the examination of several real cases that led us to take a closer look at some of the problems that occur, which are often a prejudice to the driver. Here, we show that given certain assumptions, simple solutions do exist, and that they can significatively improve the quality of traffic. We use simple criteria to measure the quality of traffic and support our claim.