Sub-problem 1a: Analysis of the Existing TWSC Intersection

Step 2: Results

What is the level of service of this unsignalized intersection today? In the future? Results of our TWSC analysis of the Museum Road/Reitz Union intersection under existing conditions are shown in Exhibit 5-12 below.

As you can see, the most pertinent information gained from this exercise might be the delay and level of service experienced by the SB movements, which we expect to be intensified by the addition of traffic for the new parking structure. Another item to note is that the northbound approach shows LOS F; but with so few vehicles, a field visit would show no queues or apparent problems. This is because LOS is based on delay in seconds per vehicle without regard to the number of vehicles being affected.

How might you interpret the estimates of delay at an unsignalized intersection to acknowledge the limitation of the methodology? While the queue and delay estimates are what the HCM methodologies provide, one might consider whether 999 seconds of delay is realistic. Essentially, this value is calculated from the equation in the HCM, and one might question whether a vehicle would actually experience over 18 minutes of delay during the peak 15 minutes. For this reason, reporting that the delay is greater than the upper threshold of LOS (>50 sec) would probably be more appropriate. For further detail, see page 17-26 in the HCM.

What is the effect of pedestrians on the intersection? One area worth a closer look would be the effects of high pedestrian volumes. Comparing the results with the high pedestrian volumes to a similar run without pedestrian interference will help illustrate the effects this aspect of the intersection has on the results. This comparison of queue, delay, and LOS is shown in Exhibit 5-13.