  This paper is a continuation of [2] where a new model of biological invasions
in the plane directed by a line was introduced. Here we include new features
such as transport and reaction terms on the line. Their interaction with the
pure diffusivity in the plane is quantified in terms of enhancement of the
propagation speed. We establish conditions that determine whether the spreading
speed exceeds the standard Fisher KPP invasion speed. These conditions involve
the ratio of the diffusivities on the line and in the field, the transport term
and the reactions. We derive the asymptotic behaviour for large diffusions or
large transports. We also discuss the biological interpretation of these
findings.
