It may simply not be possible to re-engineer some of these streets without a lot of demolition of buildings too. If pedestrians won’t exercise common sense in an area with narrow sidewalks and streets, there isn’t much that can be done to make them do it. Are they going to have jaywalking police on the scene all day?
In that case, the engineering would involve narrowing the street to make room for a wider sidewalk. The key is to have a street that works in the context of the area where it is located. Having an eight-lane wide boulevard in an area with lots of pedestrians doesn’t make any sense, for example.