Saturation flow is a very important road traffic performance measure of the maximum rate of flow of traffic. It is used extensively in signalized intersection control and design. Saturation flow describes the number of passenger car units (PCU) in a dense flow of traffic for a specific intersection lane group. The design, the capacity and operation of a signalized intersection critically depend on and passenger car unit (PCU) and saturation flow.
Saturation Flow Rate can be defined with the following scenario: Assume that an intersection’s approach signal was to stay green for an entire hour, and the traffic was as dense as could reasonably be expected. The number of vehicles that would pass through the intersection during that hour is the saturation flow rate.