Traffic Signal Design MCQ with answer and solution

Concept

Traffic-actuated signals use detectors to change phase and cycle timings based on real-time traffic demand.

Step-by-step solution

1. Fixed time signal: cycle and phase timings are pre-set and do not change with traffic. 2. Pedestrian signal: gives the right of way to pedestrians at crossings. 3. Manually operated signal: a person (traffic police) changes the signal by hand. 4. Actuated signal: detectors sense vehicles, and phase and cycle timings change according to traffic demand. 5. So the answer is (D).

Explanation

In an actuated traffic signal, detectors placed on the approach roads sense arriving vehicles. The controller then extends or changes the green time and the cycle length based on the demand. Fixed time signals cannot do this.

Why the other options are wrong

A: Fixed time signal has constant pre-set timings. B: Pedestrian signal only controls pedestrian crossing. C: Manual signal is changed by a person, not automatically by demand.

Shortcut

'Changes with traffic demand' = vehicle-actuated signal.

Common mistake

Confusing manually operated signals with actuated signals because both can vary timing.