This climb begins about 90 miles into the Death Ride (after about 12,100' of climbing).
This is the one pass that is not closed to motor vehicles during the Death Ride. You will likely be climbing into a moderate to strong head wind the entire 14 miles or so up the pass, so be prepared. While the "average grade" is only 3.7%, be mentally prepared for a long steady slog into the wind; you will be rewarded with ice cream at the top. The 3.7% average grade is misleading because there are several miles of flat riding which makes the remaining climb much steeper than 3.7% - more in the 6% range, but never anything extreme (although it surely may seem that way after so much riding and climbing).
Although not marked on the Death Ride course map for 2014, there has been a rest stop half way up Carson Pass the years we have participated (2009-2015).
Roadway surface and traffic: Roadway surface is very good and there is a clear and wide bike lane most of the climb. However, this is clearly a highway which will be very obvious to you as cars, trucks, trailers (even cyclists by this time, depending on how you feel) will whiz by. The organizers put out signs in many locations warning drivers of the event and drivers would have to be completely unconscious of their surroundings to under-appreciate the presence of cyclists on Carson Pass during the Death Ride.