Driving & Driving Test Tips: Prima facie speed limits, thumb nail sketch, speed surveys

Question
Prima facie speed limits.

What is that?  

Answer
the speed limit as determined by the roadway and usually speed surveys.  a street may have a 50 mph limit based upon it being in a wide street with minimal residential occupancy, and  a survey found that 85 percent of motorists drive between 40-60 mph along this street.  therefore the prima facie speed limit is set at 50.  there are other factors that can be used, but this is the thumb nail sketch of what prima facie is determined.