A lattice gas model with biased random walkers is presented to mimic the pe
destrian counter flow in a channel under the open boundary condition of con
stant density. There are two types of walkers without the back step: the on
e is the random walker going to the right and the other is the random walke
r going to the left. It is found that a dynamical jamming transition from t
he freely moving state at low density to the stopped state at high density
occurs at the critical density. The transition point is given by p(c) = 0.4
5 +/- 0.01, not depending on the system size. The transition point depends
on the strength of drift and decreases with increasing drift. Also, we pres
ent the extended model to take into account the traffic rule in which a ped
estrian walks preferably on the right-hand side of the channel. (C) 1999 El
sevier Science B.V. All rights reserved.