Caltrans has initiated a full closure along Highway 12/121 in Schellville, which is expected to last through Oct. 31.
Westbound traffic is being detoured onto Napa Road to Eighth Street, then back to Hwy. 12/121. Eastbound traffic follows the reverse route.
For real-time traffic updates and detour information, travelers can visit Caltrans QuickMap at quickmap.dot.ca.gov
The closure, which began Wednesday, Oct. 1, affects a segment of the highway just east of Eighth Street, where crews are replacing outdated railings on the Arroyo Seco Bridge.
This project is the first phase of a two-bridge improvement plan.
Caltrans is tentatively scheduled to replace railings on the nearby Yellow Creek Bridge on Hwy.12/121 sometime later this year or in early 2026.
Built in 1923, the Arroyo Seco Bridge is a two-lane, shoulder-less structure spanning Schellville Creek. The existing railings — which serve as guardrails to prevent vehicles from veering off the bridge — are as old as the bridge itself and do not meet current safety standards. Replacing these railings is part of Caltrans’ ongoing efforts to enhance roadway safety across the state.
Motorists are advised to expect delays and plan extra travel time, especially during peak commute hours.
Caltrans recommends adjusting routes or scheduling non-time-sensitive trips outside of these hours to ease congestion.