In one of the toughest mountain stages of the 2009 Tour de France, Jens Voigt, of the Saxobank team, suffered a severe crash and was taken for medical treatment. He’s out of the tour. Here’s one of the less grisly pictures.
Stage 16, Martigny, Switzerland to Bourg-Saint-Maurice, had very long slopes, with climbs and descents more than 20 km long. That lets a rider get exhausted on the climbs and reach dangerous speeds on the descents.
The profile for Stage 16 looks like this: