I think that this is probably valid. Many people, without knowing the posted limit, will actually travel slower that what it is (or would be). This wouldnt' be

I think that this is probably valid. Many people, without knowing the posted limit, will actually travel slower that what it is (or would be). This wouldnt' be the case on interstate roads, but on more rural roads. Some people always try and stick on the limit even if the road conditions are not at the optimum.