Basically the title. I’m curious what they do to decide. surely they don’t just stick a random number on a sign and call it a day.
In: 16
There are guidelines that help with the settings of them. However things which are considered are the: geometry of the road, visibility, what kind of traffic is most likely to be on it (Small cars, heavy machinery, big trucks, farm equipment), how much traffic is there, what are potential hazards. From this an estimation is made by comparing it to roads with similar properties and how many accidents there are on it. There are different figures for this, but I know that in Finland the rule of thumb is that 10km/h reduction in speeds reduces the chance of an accident by 10% (The figure used isn’t exactly that, it was like 9km/h reduction reduces the accidents by 7,5% or about there).
Speed limits are not arbitrary, they are based on statistics and guidelines. There is a whole field of art and science to balancing out traffic flow and probability of accidents. But we know for a fact that if the speed limit is reduced (and people follow it) there will be less accidents and less deadly accidents.
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