It's a speed camera that detects speeders, and rather than give them a ticket, it turns the traffic lights ahead red, forcing them to stop. Brilliant.

But you don't even need it...

The ultimate rule of driving that has done the most to ensure I always keep the speed limit is simple.

I heard from someone in traffic management that the traffic lights in Melbourne, particularly in the suburbs, are designed around cars doing the speed limit. Ultimately, unless you speed at insane levels, you're unlikely to get anywhere much faster because of traffic light patterns.

I tested this in 2000 with a friend who sped all the time. We both left the same place (Hughesdale) at the same time. He sped off, I drove at or under the speed limit.

At almost every traffic light I was right behind him.

Test it for yourself. Next time you see some insane idiot weaving in traffic, see where he is at the next traffic lights...