Even if the swept path issues were not an issue here, that method has been tried and tested, doesn't work, and is considered bad design practice in the field of traffic engineering.

There's a great deal of evidenced backed engineering practices and solutions to draw from to solve issues like this. Unlike software in noncritical applications, you can't just pull things out of a hat and hope it works. People die if you do that.

You can't just say "here's how fast you can drive this road." You have to design the features of a road to calm traffic. If you design a road like a freeway and then put up a 15mph speed limit sign, people aren't going to just drive 15mph. Thats just not how traffic and people work. If you want people to go slower you should design traffic calming features into the road.

Its generally bad to have inconsistent design speed for different features of a road. And by bad I mean people will get killed at disproportionate rates. It happens all the time anyway for various reasons but not very often.