How effective are speed limiters for repeat offenders?

A Dutch study [40] shows that speed limiters, or an intervening ISA, may be effective as a sanction for serious speed-limit offenders. As long as the systems is activated, average speed is lower, speed is more homogeneous and limits are exceeded less often and to a lesser degree. Yet, as soon as the system is disconnected, the effect will disappear. Furthermore, the participating offenders regularly used the panic button to bypass the system. In the same study, the effect of an advisory ISA was also assessed. The effect on speed, though somewhat smaller, was still positive as long as the system was activated, while it disappeared when the system was de-activated.