Driving in dense fog is a typical coordination problem from rational choice theory and requires compliance with a common rule in order to avoid crashes. It is not enough to say that people should drive at a reasonable speed and keep a sufficient distance, because everyone interprets this differently: one driver slows down to 120, another to 100, a third to 60, while a fourth switches on the hazard lights and starts braking.
Daniel Smilov wrote this on Facebook.
That is why the approach used by Serbia, Austria, Croatia... and many other countries, with special markings in the emergency lane, is better.
If you can see two dots in the fog, slow down to 60 km/h; if you can see one, slow down to 40 km/h. This ensures better coordination and leaves no room for all kinds of interpretations.
For this system to work, however, in addition to laying the markings and installing the relevant road signs, it is also necessary to train young drivers and run explanatory media campaigns for everyone.
Still, this appears to be the best of the proposed solutions and far more effective than installing 20 illuminated information boards between Burgas and Sofia: these boards will only tell you that there is fog somewhere (which is useful), but they will not solve the coordination problem of exactly when, where and by how much to slow down.