A lot of the problem is that because of the hill climbs some vehicles are travelling at 75-80mph while others (especially big rigs and under-powered smaller cars) are travelling 55-65mph.  This causes a lot of last minute brake slamming and lane changes.  That coupled with the curvature right south of 470 makes this stretch hair raising to drive at times.  I like being able to go fast, but maybe a lowering of the speed limit between Castle Rock and Lone Tree would be warranted.