Orange County, Calif., is studying the feasibility of converting several existing freeway carpool lanes into tolled express lanes to help alleviate increasing congestion. The plan, which is still a decade away from implementation, would include portions of Interstates 5 and 405, and state routes 5, 557 and 91, though other major roads may be added. The Orange County Transportation Authority already operates 10 miles of tolled express lanes on SR-91, while Caltrans is in the midst of a $2-billion, 16-mile express lanes project on I-405.