  We investigate the transition induced by disorder in a periodically-driven
one-dimensional model displaying quantized topological transport. We show that,
while instantaneous eigenstates are necessarily Anderson localized, the
periodic driving plays a fundamental role in delocalizing Floquet states over
the whole system, henceforth allowing for a steady state nearly-quantized
current. Remarkably, this is linked to a localization/delocalization transition
in the Floquet states of a one dimensional driven Anderson insulator, which
occurs for periodic driving corresponding to a nontrivial loop in the parameter
space. As a consequence, the Floquet spectrum becomes continuous in the
delocalized phase, in contrast with a pure-point instantaneous spectrum.
