  We study the possibility of realizing robust helical surface states in
$Z_2=0$ systems. We find that the combination of anisotropy and finite-size
confinement leads to the emergence of robust helical edge states in both 2D and
3D $Z_2=0$ systems. By investigating an anisotropic Bernevig-Hughes-Zhang model
in a finite sample, we demonstrate that the transport manifestation of the
surface states is robust against non-magnetic disorder, resembling that of a
$Z_2 = 1$ phase. Notably, the effective energy gap for the robust helical
states can be efficiently engineered, allowing for potential applications as
valley filters and valley valves. The realization of emerging robust helical
surface states in realistic material is also discussed.
