  We present a new mode of transport of spherical particles in a horizontally
vibrated channel with sawtooth shaped side walls. The underlying driving
mechanism is based on an interplay of directional energy injection transformed
by the sidewall collisions and density dependent interparticle collisions.
Experiments and matching numerics show that the average particle velocity
reaches a maximum at 60% of the maximal filling density. Introducing a spatial
phase shift between the channel boundaries increases the transport velocity by
an order of magnitude.
