What does effective green, g, represent in interrupted flow conditions?

• A. Actual green time plus total cycle time
• B. Actual green time minus the lost time due to vehicle acceleration
• C. Total time in green light for all vehicles
• D. Percentage of effective green time during peak traffic

Answer: (B)

In the context of traffic flow analysis, effective green time, denoted as "g," represents the time during which vehicles on the green signal can efficiently clear the intersection without delays. In interrupted flow conditions, factors such as vehicle acceleration and the time it takes for vehicles to react to the green light play a significant role in determining how much of the green time is actually beneficial.

The concept of effective green time accounts for the delays that occur when vehicles start moving once the signal turns green. Specifically, it is defined as the actual green time available for vehicles to use, adjusted for the lost time incurred due to acceleration. This means that when calculating the effective green time, one must subtract the time taken for vehicles to begin moving from the total green time. This lost time manifests as a reduction in the overall effectiveness of the green light because not all of the green time is utilized for vehicle movement; a portion of it is effectively wasted as vehicles are not instantaneously in motion.

This understanding is pivotal in traffic engineering, as it influences the calculation and optimization of signal timing to improve traffic flow and reduce congestion. The focus on lost time emphasizes the need for accurate assessments of how traffic signals are functioning relative to the conditions experienced by drivers, ensuring more reliable traffic management