Arguably your plan would take longer to implement as you would need standardization across vehicles, implementation into actual cars, extensive testing, adoption by drivers, codification into the law with some enforcement mechanism and implementation on selected locations. It's a cool creative idea but redesigning a junction seems like something more within reach and that can actually prevent crashes in the meantime.

If you want to tackle speeding on highways, income-based fines from speed cameras seem like the way to go. It is more feasible, can be implemented more quickly and easily and is cheaper overall.

So really, it seems like a new expensive tool with questionable relative benefits that would take really long to deliver (not to mention the privacy / freedom concerns its existence would raise) while the existing tools haven't even been used yet.