  A generalised model for interacting self-avoiding trails on the square
lattice is presented and studied using numerical transfer matrix methods. The
model differentiates between on-site double visits corresponding to collisions,
and crossings. Rigidity is also included in the model. The model includes the
Nienhuis O(n=0) model and the interacting self-avoiding trail model as special
cases. It is shown that the generic type of collapse found is the same as the
pure interacting self-avoiding trail model.

Statistical Mechanics