Road accident studies have shown that the most effective way to alert road users to the presence of another human, is to make the human form as recognisable as possible. When the driver recognises the rider as a human form, their animal instincts kick in and changes their whole approach to the rider. They naturally will take much greater care, slow down and give the rider more space.
Lighting the rider through 360 degrees to create a 3D shape also improves other road users' judgement of speed and distance.
The Oxford Metro-glo helmet is one of the vital components to deliver this visibility to cycle riders, giving both visible and practical protection.