Sub-problem 4d: Further Consideration of the Northbound Right Turn

What is the basis for determining LOS in the unsignalized intersections methodology? HCM Chapter 25 provides a procedure for estimating freeway merge area performance in terms of the traffic density. Density is used in all HCM freeway-related chapters as an indicator of congestion level. The density thresholds for each LOS are given in Exhibit 3-33.

Chapter 25 of the HCM suggests that these procedures may be applied, in an approximate manner, to completely uncontrolled ramp terminals on other types of facilities such as multilane and two-lane highways. Since an approximation is what we are seeking, we can apply the procedures with some confidence.