> Now, while there are certainly many more or less valid arguments for a speed limit, I have never heard anyone arguing about the number. The verocity of the de

> Now, while there are certainly many more or less valid arguments for a speed limit, I have never heard anyone arguing about the number. The verocity of the debate is contrasted by a total lack of arguments for or against a specific limit. Why 120 and not 130 or 90. What about 160? You could ask the same question for basically every other limit. Why is the speed limit in cities usually 50 and not 40 or 60? Why do you need to be at least 18 years old to have the right vote, why not 17 or 19, ...? In the end most of those limits aren't determined by a single argument but by many. Speed limits have to take into account the road quality, the traffic density, the kind of vehicles sharing the same road, how many pedestrians are around, environmental aspects like wind speeds, ... You also don't want vehicles with huge differences in speed. The later is my favorite argument against the missing speed limit on parts of the German Autobahn. You can have everything between stopped vehicles in a traffic jam, a tractor with 60km/h, trucks at 100km/h or less when they struggle with inclines, the average cars at around 130km/h, the business people rushing from one place to the other at 160-220km/h and those who just like to have some fun with their sports cars or bikes at >200km/h with no limit. Of course I have no idea what the best limit should be in every case, instead I suggest to figure this out with lots of experiments. Introduce certain speed limits on certain parts and find out what an effect this has on the number of accidents, traffic jams, efficiency, noise, etc... Then the speed limit can be adapted according to those results.