Cycling into Fyshwick from Dairy Flat road, there is only one safe off-road option (and Fyshwick is one place where you really want to avoid the roads as a cyclist), and not only is tribulus terrestri growing on the sides of the path, but some bright spark with a mower persistently finishes the job by scattering the caltrops all over the paths. Once the mowing is finished, run the mower on the path to blow the thorns off the path again. Not hard.
Caltrop is becoming increasingly invasive, but I would rather it lie undisturbed across half the pathway where I can see it than have it mown and the hard-to-see caltrops left scattered all over the path. Another good intention paving the way to Hell.