how to estimate air velocity near the running high-speed railroad?
 

Hi all,
this question has come from my simple idea.

We all know the wind rises when veihicles pass near us.

How do we estimate air velocity near the running vehicle(cars,railroad etc..)? the observer stays and doesn't move.

In my opnion, please look at the picture i attached.

Black line is the streamline that we can easily think wth our experience,
and red region will have higher velocity than freestream like a airfoil.

Then, I think we can calculate what i want by (V_observer = V_inf - V)
like a relative velocity in dynamic mechanics.

Am I right? I expect to set a safety line in which people should stay away from the passing vehicle with V_observer.

like a .... Drag force(from V_obsrver or pressure distribution) < Friction Force(from peapole's weight, C_f of shoes)
for accident prevention.

How do you think?