stucking effects between the pedestrians. Whenever two or more pedestrians try to attempt to move to the same target cell, the movement of [*all*]{} involved particles is denied with the probability $\mu$, i.e. all pedestrians remain at their site (see fig. \[plot\_0\]). This means that with probability $1-\mu$ one of the individuals moves to the desired cell. Which particle actually moves is then determined by the rules for the resolution of conflicts as described in Sec. \[confnofric\]. Note that for vanishing friction $\mu=0$ we recover the dynamics studied in [@ourpaper; @PED01a; @PED01b; @aki0].

![Refused movement (for $m=4$) due to the friction parameter $\mu$. []{data-label="plot_0"}](\DIR/fig2.eps){width="0.85\columnwidth"}

The friction parameter might be interpreted as the effect of a moment of hesitation: Pedestrians in conflict situations slow down or hesitate for a short moment when trying to resolve the conflict. This reduces on average the velocities of all involved particles.

With the above definition of $\mu$ and the extended update rule it is easy to see that $\mu$ works as some kind of local pressure between the pedestrians. If $\mu$ is high, the pedestrians handicap each other trying to reach their desired target sites. As we will see, this local effect can have enormous 