The chart traced the course of an Olympic race called the "snowboardcross" (one word ?!) It compresses many dimensions onto the printed page, including the relief of the course, the changing positions of the racers at each turn, the time dimension and the identities of the racers.
The design is clean and efficient so that the data do not overwhelm us.
I suspect that readability can be enhanced by toning down the shading and shaping of the relief features but as it stands, it is still a marvellous chart.
Reference: "Westcott Outlasts the Cranks and the Crashes to Win the Gold", New York Times, Feb 17 2006.