certainly not tradescantia; we spotted this type of plant a couple of times before in the area Dianella tasmanica but so far were unable to id; most likely introduced.
Thanks Michael. I'm a bit puzzled by the notification I got that this is a new species for this site given that I've posted previous sightings of it? See https://canberra.naturemapr.org/sightings/4496308, https://canberra.naturemapr.org/sightings/4496304.