Driven transport on parallel lanes with particle exclusion and obstruction

We investigate a driven two-channel system where particles on
different lanes mutually obstruct each other's motion, extending an
earlier model by Popkov and Peschel Phys. Rev. E 64, 026126
(2001)]. This obstruction may occur in biological contexts due to
steric hinderance where motor proteins carry cargos by "walking" on
microtubules. Similarly, the model serves as a description for
classical spin transport where charged particles with internal
states move unidirectionally on a lattice. Three regimes of
qualitatively different behavior are identified, depending on the
strength of coupling between the lanes. For small and large
coupling strengths the model can be mapped to a one-channel
problem, whereas a rich phase behavior emerges for intermediate
ones. We derive an approximate but quantitatively accurate
theoretical description in terms of a one-site cluster
approximation, and obtain insight into the phase behavior through
the current-density relations combined with an extremal-current
principle. Our results are confirmed by stochastic simulations.