This is a useful guide to conduct research at signalized intersections having either saturated or oversaturated conditions during peak hours. It is a research work that took place in a Mexican city where, like in other countries of Latin America, research on the topic has been limited or very little, as compared to the undertaken for more than 60 years in the United States or the European Union. For those with a basic knowledge in traffic engineering, it is well known that saturation flow rate, the parameter that results from the average headway of a line of vehicles waiting for the traffic light changing from red to green, may widely vary depending on a number of traffic volume, geometric layout and control conditions. Refered to driver behavior, these conditions represent or mean variables affecting the final outcome of the research, i.e. saturation flow rate. You may find out the chosen conditions as variables for this specific case, and pick other ones to make some interesting comparisons of this parameter among different cities around the world.