  A strong coupling between the electron spin and its motion is one of the
prerequisites of spin-based data storage and electronics. A major obstacle is
to find spin-orbit coupled materials where the electron spin can be probed and
manipulated on macroscopic length scales, for instance across the gate channel
of a spin-transistor. Here, we report on millimeter-scale edge channels with a
conductance quantized at a single quantum 1 $\times$ $e^2/h$ at zero magnetic
field. The quantum transport is found at the lateral edges of three-dimensional
topological insulators made of bismuth chalcogenides. The data are explained by
a lateral, one-dimensional quantum confinement of non-topological surface
states with a strong Rashba spin-orbit coupling. This edge transport can be
switched on and off by an electrostatic field-effect. Our results are
fundamentally different from an edge transport in quantum spin Hall insulators
and quantum anomalous Hall insula-tors.
