Traffic Flow Characteristics MCQ with answer and solution

Concept

Calculation of maximum traffic flow capacity

Formula

q_max = (v_f × k_j) / 4, where k_j = 1000 / s

Step-by-step solution

1. Jam density kj = 1000 / average spacing = 1000 / 6.5 = 153.85 vehicles/km. 2. Free mean speed vf = 70 kmph. 3. Maximum flow qmax = (vf × kj) / 4 = (70 × 153.85) / 4 = 2692.3 vehicles/hour/lane. Answer: A

Explanation

Jam density is computed as 1000 divided by the vehicle spacing of 6.5 m, which equals approximately 153.85 vehicles per kilometer. According to Greenshields model, maximum flow occurs at half the free mean speed and half the jam density. Multiplying 35 kmph by 76.92 vehicles per km yields a maximum flow of approximately 2693 vehicles per hour per lane, making option A correct.

Why the other options are wrong

NONE

Shortcut

Maximum traffic flow capacity q_max = (V_f × k_j) / 4, where jam density k_j = 1000 / average spacing.

Common mistake

Selecting option D or C by using q = V_f × k_j directly instead of dividing by 4 to calculate maximum flow capacity.