The final four-mile expressway segment for Interstate 15 was opened Jan. 16, giving drivers an additional two lanes in each direction from Escondido south to San Diego at the intersection of I-15 and state Route 163.

Built in the freeway median, the express lanes are free to cars with more than one rider, van pools, buses, permitted clean air vehicles, and motorcycles. The lanes are also available to solo drivers who pay varying tolls via the FasTrak system.

The San Diego Association of Governments, the transportation planning agency that built the lanes, is working with other agencies and companies by offering a variety of cash incentives to encourage the lane usage.

The I-15 express lanes were built in three segments and opened in stages starting in 2008. The total cost of the entire project is $1.3 billion, according to Sandag.

— Mike Allen