[kmcgivney]

That conclusion is a weakly implied by the research (at least the way it was explained), which was based on "a computer model of how a crowd of people move across a confined space".

They did not clarify how it applied to car-traffic. For instance, people react very differently to minor collisions while walking versus driving. I'm just guessing here, but I would think the simulation does not account for complicated behavioral factors (e.g. some people, when cut off, may overrreact when hitting their brakes, thus causing more traffic behind them).