The SR-91 is a heavily traveled east-west corridor through Riverside and Orange Counties, California. The SR-91 Corridor Improvement Project extended the tolled express lanes west into Riverside County from the Orange County line to I-15, a distance of approximately eight miles, replacing the existing HOV lanes. The project also added one general purpose lane in each direction and made improvements to bridges and interchanges, including the addition of auxiliary or merge lanes for improved access. Direct connectors to/from the express lanes to I-15 south of SR-91 as well as a total of 32 bridge structures were constructed as part of this project.