Module 3 : Microscopic Traffic Flow Modeling

Lecture 14 : Car Following Models

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	Optimal velocity model The concept of this model is that each driver tries to achieve an optimal velocity based on the distance to the preceding vehicle and the speed difference between the vehicles. This was an alternative possibility explored recently in car-following models. The formulation is based on the assumption that the desired speed $v_{n_{desired}}$ depends on the distance headway of the $n$th vehicle. i.e. $v_{n_{desired}}^t = v^{opt}{({\Delta}x_n^t)}$ where $v_{opt}$ is the optimal velocity function which is a function of the instantaneous distance headway $\Delta x_n^t$. Therefore $a_n^t$ is given by $${a_n^t} =[1/\tau][V^{opt}{({\Delta}x_n^t)}-{v_n^t}]$$ (1) where $\frac{1}{\tau}$ is called as sensitivity coefficient. In short, the driving strategy of $n^{th}$ vehicle is that, it tries to maintain a safe speed which in turn depends on the relative position, rather than relative speed.