  We analyze the pattern formation in systems of active particles with chiral
forces in the context of pedestrian dynamics. To describe the interparticle
interactions, we use the standard social force model and supplement it with a
new type of force that reflects chirality. We perform numerical simulations of
two pedestrian flows moving in opposite directions along a corridor. We observe
two dynamic phase transitions that occur for varying number densities of
particles and strengths of the chirality force: one from disordered motion to
multi-lane motion and another from multi-lane to two-lane motion. We develop a
qualitative theory that describes the demarcation lines for these phase
transitions in the phase diagram chirality-density. The results of our analysis
agree fairly well with the simulation data. A comparison with previously
reported experimental data has been provided. Our findings may find
applications in urban and transportation-planning problems.
