Problem 4: Analysis

In Problem 4, we explored the effects of traffic-actuated control on the performance of the U.S. 95/Styner-Lauder Intersection. Traffic-actuated control is a function of the detection system and the signal timing active within the signal controller at the intersection. In detailed operations analysis, the use of detector timing presents an additional level of complexity for our analyses and thus, may more closely reflect field conditions.

In sub-problem 4a, we considered the effect of actuated control that revisits our assumption regarding cycle length and phase time. This analysis assumes fully-actuated control typical of an isolated operations.

In sub-problem 4b, we examined the effect of unit extension on phase length and its corresponding effect on cycle length at a fully-actuated intersection. We learned that as the unit extension (commonly referred to as passage gap in signal controller manuals) increases, the phase length and cycle length increase.

In sub-problem 4c, we revealed the implications of a coordinated operations on an actuated signal. Specifically, the introduction of a fixed cycle length may result in increased delay to the side street but improved operations and progression along the arterial.

Finally, in sub-problem 4d, the effect of left-turn protection is considered. In this analysis, we learn how to estimate the percentage of cycles that will result in left-turn actuation.