Among the PowerPoint slides shared with colleagues by vascular surgeon Dr John Crozier are videos of e-scooter falls and the gory images of the wounds which result.

But Dr Crozier, chair of the Royal Australasian College of Surgeons National Trauma Committee, says the most chilling slides feature only dummies, computer models and graphs, tracking the velocities at which the body parts move in a crash.

In the first 200 milliseconds, photos of crash test dummies document their brief but doomed flight with the subsequent 400 milliseconds tracking a rapid descent.

The dummies cannot stick their hands out to protect their heads, and neither can many human riders subject to similar physics.