I just came across a very interesting historical nugget.
On November 15 1902, the Star Newspaper in Johannesburg published a letter by someone complaining about the increasing speeds of motor cars. He was very distressed that a friend of his nearly fell of his horse when a car travelling at least 18 miles an hour (about 29kms/hr) whizzed by.
He requested that the Town Council revert to the previously set 7 miles an hour (11kms/hr) speed limit for all vehicles. Anything else would “constitute[s] a public danger.”
How things change. These days in Johannesburg 60kms/hr is considered a lazy pace. It may be the case in many other cities in the world. Perhaps this is why 30km/hr is considered a desirable campaign goal that may increase the safety of cyclists and pedestrians. For example see this campaign.
What will the near future bring I wonder.