Question

A signalized intersection has a sum of critical flow ratios of 0.72 and a total cycle lost time of 12 seconds. Assuming a critical intersection v/c ration of 0.9, calculate the minimum necessary cycle length.

Answer 1

To determine the minimum necessary cycle length for a signalized intersection, we use a specific formula involving the sum of critical flow ratios, total cycle lost time, and the v/c ratio. The calculated cycle length is approximately 226 seconds, enhancing pedestrian safety by systematically controlling the flow of traffic.

Step-by-step explanation:

The question is asking to calculate the minimum necessary cycle length for a signalized intersection, given the sum of critical flow ratios (0.72), the total cycle lost time (12 seconds), and the target critical v/c ratio (0.9). To find the minimum cycle length, we use the formula: C = rac{5L}{1-V} + L, where C is the cycle length, L is the lost time, and V is the sum of the critical flow ratios. Substituting the given values we get: C = rac{5(12)}{1-0.72} + 12 = rac{60}{0.28} + 12 ≈ 214.29 + 12 ≈ 226.29 seconds. Therefore, the minimum necessary cycle length is approximately 226 seconds.

It's important to note that enhancing pedestrian safety is a significant concern at intersections. A traffic signal improves safety as it systematically controls the flow of both vehicular traffic and pedestrians, allowing for a safer crossing experience.

Answer 2

`T_o=82.1sec`

Step-by-step explanation:

From the question we are told that:

Lost Time
`t=12secs`

Sum of critical flow ratios
`X=0.72`

Generally the Webster Method's equation for Optimum cycle time is is mathematically given by

`T_o=(1.5t+5)/(1-x)`

`T_o=(1.5*12+5)/(1-0.72)`

`T_o=82.1sec`