Best way to slow down traffic in a subdivision is round abouts. Seems people in Ontario have no idea what to do when they arrive at one. You can see people arrive at them stop at the yield sign, then they signal left, then right, then their head Explodes.
You can put in rules like you must drive through subdivision with 4 way flashers on, eating a jelly. Donut, while playing Chopin. The issue is enforcement, with 100000 rules on the book for driving and the only enforcement is during cracked downs or the occasionally ticket due to luck.
For the most part people obey the rule, there are the dickheads, but the majority never get caught, but granny does 5 over and pow ticket. What did it accomplish.