  There remains the old question of how long a quantum particle takes to tunnel
through a potential barrier higher than its incident kinetic energy. In this
article a solution of the question is proposed on the basis of a realistic
explanation of quantum mechanics. The explanation implies that the tunneling
particle has a certain chance to borrow enough energy from self-interference to
high-jump over the barrier. The root-mean-square velocity and the effective
tunneling time of an electron tunneling through a rectangular barrier are
numerically calculated. No superluminal effect (Hartman effect) is found for
the tunneling electron. Heisenberg's energy-time uncertainty relation for the
tunneling effect is verified by calculating an introduced coefficient
representing uncertainty. The present author argues that phase time, dwell time
and B\"{u}tticker-Landauer time are not appropriate expressions for the actual
transit time in a tunneling process. A quantum high-jumping model is presented
to resolve the paradox that kinetic energy of the tunneling particle is
negative and its momentum is imaginary.
