I think it is fairly well established that sticking 40 or 30km/h speed limit signs around the place is not that effective. People either ignore them or whinge about them. You change behaviour by changing the built environment. Traffic is slowed very easily by narrowing the street, removing the painted line in the middle of the road and by making it much harder to speed around corners. It amazes me that there are not more prangs involving cars at residential intersections. So often we see drivers take a right turn at speed and on the wrong side of the road. It is a matter of pure dumb luck that there is not someone coming the other way at that point. They are generally just a few metres back. Enough to make the driver swerve just a little but not quite enough of a scare to stop the practice.
Narrowing the road at intersections can serve a number of purposes. If you make the street narrow enough, only one vehicle at a time can get through. That certainly slows things down. Narrowing the street also makes it easier for pedestrians to cross - they don't have quite as far to walk. As part of the narrowing you can also send a clear signal by making the pavement continuous so that cars have to be driven across the pavement. You would think that would send a pretty clear signal about right of way.
Another positive about build-outs at intersections is that they can be turned into stormwater gardens. If the local council advertises well enough, there is generally a helpful neighbour who would be happy to adopt it and tend to the plants.
Doing the right thing on corners can not only bring the place alive but it can boost business. Here's a corner on Wright Street where the Jam Bistro is (go there for great food and coffee served by one of the best Baristas in town - Adam. He has no hair on his head but lots on his chin. Go figure):
There is space for nearly 20 people to sit out the front. A single car takes up the same space. How easy would it be to extend the pavement further out into the street (the same width as the parked cars) and free up all that space for more tables? You would double the number of patrons for the price of a single car parking space. The person parked there probably isn't buying coffee from Adam anyway. It would be no loss at all, only a gain - for the city and local business.
Montreal shows us how: