Refugio Road Undercrossing Bridges Replacement Project

Project Description

Caltrans proposes to replace the northbound and southbound bridges at Refugio Road along U.S. 101 near Refugio State Beach (post miles R36/R37). The new concrete bridges would have about the same alignment, profile, and lane configuration as the existing bridges, but would be 7 feet wider to accommodate standard 10-foot shoulders. Two build alternatives were considered, and the clear-span bridges have been identified as the preferred alternative:

  • Two-span replacement bridges. Each bridge would have a center support column, resembling the existing bridges.
  • Clear-span replacement bridges (preferred alternative). The new bridges would not require a center support column but would appear thicker (increased depth) than the existing bridges and have larger abutments to support the longer and heavier bridge span.

Both build alternatives would also remove a partial fish passage barrier caused by the existing concrete-grouted rock slope protection lining in Cañada del Refugio Creek. The rock slope protection would be removed from the creek bed and naturalized with gravel and stone, and the riparian corridor would be replanted with trees and other riparian plants. Other project elements include upgrading bridge rails on the northbound U.S. 101 on-ramp bridge, rehabilitating the existing pedestrian pathway beneath the bridges, and updating the lighting system through the project limits.

Graphic of Project Overview Map

Project Benefits

Purpose: The purpose of the project is to ensure the safety and reliability of the U.S. 101 corridor by addressing the presence of alkali-silica reactivity in the northbound and southbound Refugio Road undercrossing bridges. Another objective of the project is to improve anadromous fish migration within the project limits at Cañada del Refugio Creek while maintaining the bank stability needed to protect the bridges from scour.

Need: The project is needed due to the presence of alkali-silica reactivity in the concrete of both Refugio Road undercrossing bridges. Alkali-silica reactivity is a widespread problem affecting Portland cement concrete that causes the concrete to swell and crack, which can ultimately lead to concrete failure and corrosion of the embedded steel reinforcement bars. Concrete core testing and inspections by Caltrans’ Structure Maintenance and Investigations Team confirmed the presence of alkali-silica reactivity in the concrete of both Refugio Road undercrossing bridges. Cracks and spalls in the bridge decks and bridge abutments have been repaired to temporarily extend the service life of the bridges, but it is not possible to permanently repair a concrete bridge structure with alkali-silica reactive aggregate.

Fish passage improvements are needed because the portion of Cañada del Refugio Creek that was lined with concrete-grouted rock slope protection during construction of the Refugio Road Bridges in 1974 is a partial barrier to the migration of Southern California steelhead trout and other anadromous fish. California Fish and Game Code Sections 15901 and 15931 make it unlawful to impede fish passage and Article 3.5 of the California Streets and Highways Code Section 156 requires that Caltrans remediate fish passage barriers for any project using state or federal transportation funds that affects a stream crossing on a stream where anadromous fish are currently, or were historically, found.

Funding Breakdown

The project would be paid for with 2018 State Highway Operation and Protection Program (SHOPP) funds and is eligible for federal-aid funding. The current year estimated capital outlay project cost is $42,515,000 for Alternative 1 and $35,539,000 for Alternative 3. 

Proposed Project Timeline

  • Draft Environmental Document Released: March 2020
  • Close of DED Public Comment Period: May 20, 2020
  • Final Environmental Document/Project Approval: February 2021
  • Project Design: Spring 2021 - Winter 2023
  • Begin Construction: Spring 2024


Dianna Beck, Senior Environmental Planner
Phone: (805) 459-9406

District 5 Public Affairs
Phone: (805) 549-3318