  We consider tunneling transitions between states separated by an energy
barrier in a simple field theoretical model. We analyse the case of soliton
creation induced by collisions of a few highly energetic particles. We present
semiclassical, but otherwise first principle, study of this process at all
energies of colliding particles. We find that direct tunneling to the final
state occurs at energies below the critical value E_c, which is slightly higher
than the barrier height. Tunneling probability grows with energy in this
regime. Above the critical energy, the tunneling mechanism is different. The
transition proceeds through creation of a state close to the top of the
potential barrier (sphaleron) and its subsequent decay. At certain limiting
energy E_l tunneling probability ceases to grow. At higher energies the
dominant mechanism of transition becomes the release of energy excess E-E_l by
the emission of a few particles and then tunneling at effectively lower energy
E=E_l via the limiting semiclassical configuration. The latter belongs to a
class of ``real--time instantons'', semiclassical solutions saturating the
inclusive probability of tunneling from initial states with given number of
particles. We conclude that the process of collision--induced tunneling is
exponentially suppressed at all energies.
