  Test particle geodesic motion is analysed in detail for the background
spacetimes of the degenerate Ferrari-Ibanez colliding gravitational wave
solutions. Killing vectors have been used to reduce the equations of motion to
a first order system of differential equations which have been integrated
numerically. The associated constants of the motion have also been used to
match the geodesics as they cross over the boundary between the single plane
wave and interaction zones.
