  Active particles may happen to be confined in channels so narrow that they
cannot overtake each other (Single File conditions). This interesting situation
reveals nontrivial physical features as a consequence of the strong
inter-particle correlations developed in collective rearrangements. We consider
a minimal model for active Brownian particles with the aim of studying the
modifications introduced by activity with respect to the classical (passive)
Single File picture. Depending on whether their motion is dominated by
translational or rotational diffusion, we find that active Brownian particles
in Single File may arrange into clusters which are continuously merging and
splitting ({\it active clusters}) or merely reproduce passive-motion paradigms,
respectively. We show that activity convey to self-propelled particles a
strategic advantage for trespassing narrow channels against external biases
(e.g., the gravitational field).
