UDOT is improving drainage at the base of Parley's Canyon through milepost 131 (about 2 miles up the canyon). The construction is impacting the shoulders of I-80, and therefore the lower canyon is closed to cyclists in both directions. Cyclists riding from Salt Lake to Park City and vice-versa are advised to follow Emigration Canyon Moutain Dell before climbing to the summit of Parley's Canyon on the shoulder of I-80. Cyclists riding from Park City to Salt Lake City should exit at Mountain Dell. The construction extends from the I-215 onramp/offramp to the rock quarry – milepost 129-131.
Lower Parley's Canyon will be closed to cyclists through November of 2013 according to UDOT's website.
More information is available here: http://www.udot.utah.gov/renovate-I-80/parleys-2/