Wonder if we could commission research into a battery powered transmitter, built into a light, that sent out a signal which interfered with wi-fi SatNavs so that they emit a warning sound when you get within, say, 100 feet [sorry 30m] of a cyclist.
... bit like those hand held speed camera detectors. Would have the same effect by slowing drivers down and making them more alert, if only until they'd spotted the hazard, ie us.