How do you discriminate a typical slowdown due to road conditions from full braking? You really cannot without additional information. But a sensor equipped (n

How do you discriminate a typical slowdown due to road conditions from full braking? You really cannot without additional information. But a sensor equipped (not even self driving) car can and forward this information. Simple things like broadcasting brake status, turning lights status and engine RPM of the nearby vehicles, and if available, emergency braking notice or traction control notice would do wonders, but we have not standardized on any such system of info somehow. Not even for people. A simple info about being passed or nearby road signs send to a car's HUD/console would do a lot for safety, potentially. Smart road, then smart cars, then self driving cars. Skipping steps won't do. Fast trains have these systems already (both local radio and central) despite much more controlled conditions, but somehow car roads don't get them.