For decades, the road had its own rules. The most important was to drive on its left side. That allowed down-bound motorists to peer out their windows and get a better look at how close their wheels were to the abyss.
Amid fog, rain and landslides, accidents killed 200 to 300 people per year.
You can read more about it here. I was once in La Paz, and unwilling to leave because it would have meant traversing this road. Nor did I have enough time to fly somewhere and back.