San Marcos SR-78 Eastbound Lanes to Close Overnight October 26–27 at Rancho Santa Fe Road

SAN MARCOS, San Diego County — October 26, 2026. A highway project that affects both local traffic and overnight trips across northern San Diego County will temporarily stop eastbound travel on State Route 78 at South Rancho Santa Fe Road on Monday and Tuesday nights, October 26 and 27.

Caltrans says the eastbound freeway will be fully closed at that interchange from 10 p.m. to 5 a.m. each night while crews replace weight-in-motion sensors. This is a specific eastbound closure at an interchange, not a seven-hour shutdown of every mile of SR-78. Drivers will be directed off SR-78 at the South Rancho Santa Fe Road exit and may reenter at the eastbound on-ramp at the same location.

Neighborhood effects: detour traffic, noise and lights

The agency warns that nearby residents and businesses should anticipate extra traffic on the surface-street detour, construction lighting and equipment noise. Portable message signs are expected to alert motorists ahead of the work zone. Workers will operate within temporary freeway closures, and the schedule can change because of road incidents, weather or operations.

Part of a larger SR-78 upgrade

The agency identifies this work as part of its $126 million SR-78 Asset Management Project, improving a 17.7-mile corridor between Oceanside and Escondido. The latest operation concerns road sensors, not completion of the entire project.

Before leaving, confirm current restrictions on Caltrans QuickMap. Original announcement: Caltrans District 11, issued October 20. More coverage at San Marcos News.

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