Pay as You Speed, ISA with incentives for not speeding: Results and interpretation of speed data

► We combined informative ISA with a Pay as You Speed (PAYS) concept. ► The results showed that ISA is an efficient tool to reduce speeding in particular on rural roads. ► Both informative ISA and incentive ISA reduced the PDA, but there is no significant interaction. ► The ISA effect disappears completely when ISA is turned off. ► The proportion of distance driven above the speed limit is the best measure to reflect the effect of ISA.