  We study the active Potts model with either site occupancy restriction or
on-site repulsion to explore jamming and kinetic arrest in a flocking model.
The incorporation of such volume exclusion features leads to a surprisingly
rich variety of self-organized spatial patterns. While bands and lanes of
moving particles commonly occur without or under weak volume exclusion, strong
volume exclusion along with low temperature, high activity, and large particle
density facilitates jams due to motility-induced phase separation. Through
several phase diagrams, we identify the phase boundaries separating the jammed
and free-flowing phases and study the transition between these phases which
provide us with both qualitative and quantitative predictions of how jamming
might be delayed or dissolved. We further formulate and analyze a hydrodynamic
theory for the restricted APM which predicts various features of the
microscopic model.
