Yellowstone's Grand Loop will have construction on roads and bridges during the summers of 2014-2016. The bulk of the construction will be in the 16-mile section of the loop between Norris Geyser Basin and the Golden Gate area south of Mammoth Hot Springs. This construction will be completed over three phases and will take a few years.
Most traffic delays will be during the night, but you can avoid this area by crossing over the center of the Loop's "eight" shape. From Norris head east to Canyon Village and then head north to Tower-Roosevelt and finally west to Mammoth Hot Springs.