  It is shown that superthin and superlong gravitational flux tube solutions in
the 5D Kaluza-Klein gravity have the region $(\approx l_{Pl})$ where the metric
signature changes from $\{+,-,-,-,- \}$ to $\{-,-,-,-,+ \}$. Such change is too
quickly from one of the paradigms of quantum gravity which tells that the
Planck length is the minimal length in the nature and consequently the physical
quantities can not change very quickly in the course of this length. For
avoiding such dynamic it is supposed that a pure quantum freezing of the
dynamic of the $5^{th}$ dimension takes place. As the continuation of the flux
tube metric in the longitudinal direction the Reissner-Nordstr\"om metric is
proposed. In the consequence of such construction one can avoid the appearance
of a point-like singularity in the extremal Reissner-Nordstr\"om solution.
