Module 1 : Traffic Stream Characteristics

Lecture 02 : Fundamental Relations of Traffic Flow

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	Relation between time mean speed and space mean speed The relation between time mean speed($v_t$) and space mean speed($v_s$) is given by the following relation: $$v_t =v_s+\frac{\sigma^2}{v_s}$$ (1) where,$\sigma^2$ is the standard deviation of the spot speed. The derivation of the formula is given in the next subsection. The standard deviation($\sigma^2$) can be computed in the following equation: $$\sigma^2 = \frac{\Sigma q_iv_i^2}{\Sigma q_i}-(v_t)^2$$ (2) where,$q_i$ is the frequency of the vehicle having $v_i$ speed.