Lowering sped limits within towns and residential areas increases the chances of a pedestrian surviving a collision with a vehicle, especially heavy good vehicles. Too many kids and old people are dying just because they walk out into the road without looking.
Lowering speed limits doesn't do much except maybe in North Korea or somewhere else where draconian enforcement to actually get compliance is palatable. It's well understood in civil engineering circles that people in aggregate drive what they consider to be the reasonable speed for the road and if you want slower traffic you need to play visual tricks to make that happen. On multi-lane roads lowering speed limits ma…
I'm not sure how you got the wrong idea that this is "[c]hanging a bunch of signs," especially since HN guidelines suggest I assume you read the linked article.