Sub-problem 5a: Two-Phase Traffic Signal Control

The application of the QEM sneaker check to this sub-problem is summarized as follows:

So, the QEM sneaker check also suggests the need for a protected left turn, because the left-turn demand (120 vph) is greater than the apparent sneaker capacity (60 vph).

The operational procedure presented in HCM Chapter 16 offers the perspective of delay and v/c ratio for the left-turn movement. These more detailed performance measures are beyond the scope of the QEM. Applying the operational procedure using the two-phase signal timing plan given by the QEM, we see the following results for the WB left turn:

These results confirm from three different perspectives that a signal operation is unlikely to accommodate the westbound left turn satisfactorily without a protected phase. The next sub-problem will examine a three-phase operation with protection for this movement.