The County of Riverside (County), in cooperation with the California Department of Transportation (Caltrans) and the City of Palm Desert (City), proposes to construct a new interchange on Interstate 10 (I-10) at Portola Avenue. The limits of work for this project are along I-10, approximately from post mile (PM) 44.8 to PM 46.6. The project includes the construction of a new structure crossing I-10 and the Union Pacific Railroad (UPRR), construction of associated on- and off-ramps, and the realignment of the adjacent frontage road, Varner Road. Auxiliary lanes in each direction of I-10 between the new Portola Avenue ramps and the adjacent interchanges at Cook Street and Monterey Avenue would also be constructed.