What specific rating, using letters like A to F, tells us how well traffic is moving on a road?

The specific rating, using letters like A to F, that tells us how well traffic is moving on a road is called Level of Service (LOS). This system provides a qualitative measure of operational conditions within a traffic stream, based on factors such as speed, travel time, freedom to maneuver, traffic interruptions, and driver comfort and convenience. The Level of Service is a standard concept in traffic engineering, primarily defined by the Highway Capacity Manual. Each letter grade signifies a different quality of traffic flow: Level of Service A represents excellent traffic conditions, characterized by free-flow operation wi....