The mean direction changed at each simulated step.
Once a simulated path crossed the road,
we changed the mean direction to the location of that individual on 15 Dec.
For individuals that came within 15 km of the road but did not cross it,
we set the mean direction to the point on the road the individual came closest to.
We simulated 100 paths for each individual,
based on each individual's empirical distributions of step lengths and turn angles.