Also known as "lining up incentives". That is, "not getting punished" is a weak incentive (especially when the odds are so low). "Maybe winning money" is a much stronger incentive (even when the odds are low). "Fun" is nice but I bet it would have very little to do with the success of this idea.
Relatedly, I've wondered why pro-follow-the-speed-limit types don't spend more time reminding people about the benefits in terms of gas mileage. On most cars you get better fuel efficiency at 65mph than 70 and still better at 55mph. (Roughly: 100km/h better than 110, and better still at 85.) In days of expensive fuel, it seems like people would/should be receptive to this argument....
Research suggests that pedestrians struck at 30 mph have about a 1 in 5 chance of being killed. At 20 mph the chance of a pedestrian dying is 1 in 40. In order to improve safety on the streets where we live, we will amend our guidance on speed limits, recommending that highway authorities, over time, introduce 20 mph zones or limits into streets that are primarily residential in nature and which are not part of any major through route. Similarly, we will encourage local authorities to consider introducing 20 mph limits or zones in town or city streets, such as around schools, shops, markets, playgrounds and other areas where pedestrian and cyclist movements are high.
Relatedly, I've wondered why pro-follow-the-speed-limit types don't spend more time reminding people about the benefits in terms of gas mileage. On most cars you get better fuel efficiency at 65mph than 70 and still better at 55mph. (Roughly: 100km/h better than 110, and better still at 85.) In days of expensive fuel, it seems like people would/should be receptive to this argument....