however the lack of evidence on the overall rollout of the ser concept eg in the netherlands is not very surprising the concept is so wrapped up in the overall dutch safety strategy which has been a general success story that it is hard to single out the effect of this particular element they tend to overestimate their speed reduction this creates a need to reinforce the perception of driving speed particularly at transitions to lower speed limits on the entry to towns and villages on the approach to intersections and on the approach to sharp curves