Driver views on speed and enforcement

Linear regression and sigmoidal models were applied to describe the linkage between the reported driving speed (dependent) and the perceived posted speed (independent). The sigmoidal model fitted the data better, especially at high levels of the perceived posted speeds. That is, although the perceived posted speed increased, at some point the actual driving speed levels off (asymptote) and did not increase. Moreover, we found that the upper asymptote of the sigmoidal model decreased over the years: from 113.22 (SE = 18.84) km/h in 2010 to 88.92 (SE = 1.55) km/h in 2013. A wide variance in perceived speed limits suggest that drivers may not know what the speed limits really are.