Sacramento and Placer counties want to complete a system of carpool lanes on a 20-mile stretch of Interstate 80, between I 5 and Highway 65. But they need about $186 million to do so. A solution the counties plan to study are high-occupancy toll lanes, also known as HOT lanes. Under this plan, the private sector would pay for and build the HOT lanes. Then, the toll revenue generated would be used to pay the private sector back for the construction costs. County officials have filed for a grant to study the I 80 corridor as a pilot project for HOT lanes. But there’s at least one hurdle. Privately funded HOT lanes require legislative approval. There’s no current statewide law enabling such projects.