Tami, that's me! Each of the two ropes runs through a gri gri. The gri gri is in turn anchored to three bolts by a set of three slings on the far bridge. I tie on to both ropes and climb over the rail. My mate then takes in on both gri gris so that the ropes go tight (but being a dynamic climbing rope there is still some bend/slack in the rope at the point that I jump). So when I jump there is some slack so the first part of the jump is a free fall down towards those rocks. You can tell from the point when I stop screaming (!) and change to hysterical laughter is the point the rope goes tight. Once I stop swinging my mate above lowers me to the rocky bed below by paying out slack on each of the ropes. Once back on the ground I untie and then climb out using a very steep path. Ropes get pulled up and are readied for the next victim.
It's 'sort of' tolerated by the authorities methinks.
The police turn a blind eye but I've heard there are often accidents on the bridge involving surprised motorists emerging from the tunnel to see someone leap from the bridge in front of them. When that happens the advice I was given was pack up very quickly and disappear.