Here is a quote from the Wikipedia Page:
Because of the extreme dropoffs, single-lane width, and lack of guardrails, the road is extremely dangerous. Further still, rain and fog can make visibility precarious, the road surface muddy, and loosen rocks from the hillsides above. On July 24, 1983, a bus veered off the Yungas Road and into a canyon, killing more than 100 passengers in what is said to be Bolivia's worst road accident.And I have found the road on Microsoft's Live Maps if you want to see exactly where it is. Which is really why I am linking to this because I think being able to fly around the earth with a 360 controller is cool.