Seriously, solutions exist on how to design and build safe streets. NACTO has published a set of line-by-line modifications to the Federal Highway Administration’s Manual on Uniform Traffic Control Devices.
One thing I’ve learned halfway through an engineering career (but I’m not claiming to be a practicing transportation engineer or expert) is that change doesn’t occur at the site or street scale until best practices from elsewhere filter down to what I call the local “playbook” for design. The playbook is the set of codes, ordinances, regulations, design standards, performance criteria, standard plans and drawings, manuals, guidelines, etc. that a local community uses for design. The status quo in these documents usually has some reason for existing, but it also has enormous inertia, to the point where it can take decades for a clear solution to a problem to make its way into actual on-the-ground designs, and today’s designs can represent solutions that were appropriate for conditions as they existed decades ago.
Local professionals and bureaucrats are not always ignorant, but they are harried and operating under pressure that leaves little time for learning. There is a certain cynicism that sets in, at least in the engineering industry, and in my opinion the “STEM” approach to education tends to nudge more literal minded thinkers (who tend to be good at math and logic) into the industry while discouraging more creative thinkers. Revised curricula and continuing education for planners, engineers, architects, the construction industry, and public officials can be part of the answer. Grass roots advocacy can also be part of the answer. But changes to official documents at the federal level can really help get the ball rolling, because states often follow suit (slowly), and then local projects are often required to follow these documents to be eligible for state and federal funding. Just one small example is that in Pennsylvania, there is (or was until recently, I’m not sure of the status) a law that cars had to be parked within a certain number of inches of a curb. Sounds reasonable enough, until you realize that it actually makes modern protected bike lanes illegal! There are lots of little things like that, and then there are big things like safe intersections with different signals for motor vehicles, bikes, and pedestrians.