State Route 78 (SR 78) serves as the primary east-west travel corridor between Escondido and Oceanside, traversing through the cities of Carlsbad, Vista, and San Marcos, as well as unincorporated areas of San Diego County. SR 78 serves as the primary route for local and regional travel in North County between these local jurisdictions and provides north-south connections to Interstates 5 and 15.
SR 78 has experienced major congestion over the recent years as more and more commercial and residential growth has occurred. Back-ups are particularly frequent near the SR 78 and I-15 interchange. To address this increased congestion, a study to evaluate plans to improve SR 78 was completed in 2012 and construction improvements just west of the SR 78/I-15 interchange were implemented. To learn more about the completed SR 78 Corridor study, visit the SR 78 Corridor Study project webpage.
SANDAG and Caltrans have proposed additional improvements proposed for SR 78, including the I-5/SR 78 Interchange, I-15/SR 78 HOV connectors, SR 78 HOV/Express Lanes, Woodland/Barham Interchange, and additional operational improvements along SR 78.