Sub-problem 4b: Two-way Stop Controlled Analysis

What movements are considered in the HCM procedures? The HCM procedures compute the capacity, control delay, and level of service for all movements that must yield to other movements, including the left turns from the major street. Through and right-turn movements on the major street are excluded from the analysis and are assumed to have no delay.

This simplifying assumption raises a point of interest. Heavy vehicles making right turns will sometimes cause significant delays to traffic on the major street. This phenomenon is overlooked by the HCM procedure. If such delays are of concern to a particular analysis, it will be necessary to apply microscopic simulation modeling tools to supplement the HCM analysis. For purposes of this discussion, we will assume that traffic delay to the through movements on the major street is not an issue.

What is the basis for determining LOS in the unsignalized intersections methodology? The level of service is based on the control delay according to Exhibit 3-29. HCM Chapter 17 prescribes the full procedure for computing control delay.