Alpe d'Huez Comparison: If you start at mile 3.83 (near the intersection with Mountain Ave at the top of the reservoir), the climb is 8.8 miles with an average grade of 7.6%. Alpe d'huez is 8.8 miles with a 7.9% average.
This is about the closest thing in Southern California that you can compare in length and steepness to Alpe d'Huez. However, if you start at mile 5 near the first tunnel, the climb is 7.6 miles with an 8.2% average. The last few miles of this climb are more dificult than most of Alpe d'huez.