  Improving emergency evacuations is a top priority in human safety and in
pedestrian dynamics. In this paper, we use the social force model, in order to
optimize high-anxiety pedestrian evacuations. We explore two architectural
layouts, the 1-door vestibule, and the 2-doors vestibule. The "vestibule" is
defined as the room next to the exit door and it is characterized by two
structural parameters: the vestibule width ($d$) and the vestibule door width
($w$). We found that, specific values of $d$ and $w$, can almost double the
evacuation flow compared to the no-vestibule scenario. The key to this
achievement is that the density (close to the exit door) can be controlled by
$d$ and $w$. Therefore, it is possible to tune these parameters to a density
that maximizes the available space while preventing the formation of blocking
clusters at the exit door ($\rho \sim 2.5\,$p/m$^2$). As opposed to the optimal
condition, low-density values ($\rho \sim 1\,$p/m$^2$) lead to suboptimal flow
since there is unused space left; while higher density values ($\rho \sim
4\,$p/m$^2$) also lead to suboptimal flow due to the presence of blocking
clusters at the exit. Moreover, we take into account the usually foreseen fact
that high pressures can actually be reached at the exit, threatening the health
of pedestrians. Therefore, we studied the crowd pressure using the agents'
overlap as an indicative. We found that the explored vestibules reduce the
crowd pressure compared to the no-vestibule situation. In particular, we show
that the 2-doors vestibule scenario performs better than the 1-door vestibule,
because it reduces the overall local density (by enforcing the crowd to spread
out more).
