Will announcing seat-belt checkpoints reduce the non-use of seat-belts or increase other violations?

Road side interviews have been conducted in order to evaluate the use of a sign “Seat-belt enforcement” at seat-belt checkpoints of the Norwegian Public Roads Administration. Currently the checkpoints are usually well visible, but no information is given to the drivers about what kind of enforcement is being conducted. The results of the interviews show that more drivers become aware of both the checkpoints and the fact that seat-belt enforcement is being conducted when the checkpoints are announced with the sign. However, the results do not indicate that the subjective risk of detection for not using seat-belts increases, as has been the intention. Self-reported future seat-belt use increases when the sign is used, but since seat-belt use seems to be somewhat overreported, especially when the sign is used, it cannot be concluded that seat-belt use actually will increase. An undesired effect of the sign that has been found is reduced uncertainty and fewer drivers who assume or suspect that other violations than non-wearing of seat-belts are being enforced. The deterrence against other types of traffic law violations may therefore be reduced when the sign is used.