Module 1 : Traffic Stream Characteristics

Lecture 02 : Fundamental Relations of Traffic Flow

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	Numerical Example If the spot speeds are 50, 40, 60, 54 and 45, then find the time mean speed and space mean speed. Solution Time mean speed $v_t$ is the average of spot speed. Therefore, $v_t = \frac{\Sigma {v_i}}{n} = \frac{50+40+60+54+45}{5} = \frac{249}{5}$ = 49.8. Space mean speed is the harmonic mean of spot speed. Therefore, $v_s = \frac{n}{\Sigma{\frac{1}{v_i}}} = \frac{5}{{\frac{1}{50}}+{\frac{1}{40}}+{\frac{1}{60}}+{\frac{1}{54}}+{\frac{1}{45}}} = \frac{5}{0.12} = 48.82.$