Problem 4: Clifton Country Road 

To treat the problem in this more systematic manner, we need to do an unsignalized intersection analysis at the two-way stop controlled intersection just to the north (visible in the aerial photograph). We will also do an analysis of the all-way stop controlled intersection beyond. We will also look at the two-way stop controlled intersection to the south. This means doing analyses based on Chapter 16 and Chapter 17 simultaneously.

In doing this, we also have to be careful to account for evidence of modifications to typical driver behavior. For example, when the westbound left-turn bays get congested, drivers that want to go south turn right instead, go north to the TWSC intersection at Old Route 146, then make a U-turn to again be headed south. They know the southbound approach will get a green before the next time the westbound left turn does. This action adds traffic to the Old Route 146 intersection and lengthens the queue on the southbound approach.

This discussion demonstrates the intersection may require other analysis methods. We may consider using a network analysis package that can simultaneously look at the performance of all the intersections we’ve discussed.

Discussion:
We return to the same discussion format used initially in the case study. We revisit the basic issues to identify the problem, how it should be approached, how large the study network should be, and what analysis tools need to be employed. Do you have facilities that are similar, where the general issue decisions you made for the overall problem need to be revisited and refined to address a more site-specific problem?