Honeydew Bridge Replacement Project

  1. Existing Conditions and Proposed Project
  2. Replacement Assessment
  3. Status as Historic Property

Humboldt County Public Works has completed design, obtained the necessary permits and funding has been allocated. Advertisement is planned for early 2024 with Phase 1 construction in 2024 followed by Phase 2 of construction in 2025.

The Honeydew Bridge was constructed in 1920 as a single-lane bridge with two steel Camelback truss spans. The bridge is supported by a reinforced concrete pier and wing abutments on spread footings. The bridge has timber decking and rails. The total bridge length is 386 feet and the vertical clearance is 14 feet. The bridge is posted to limit truck and bus speeds to 15 miles per hour.

The bridge is classified as functionally obsolete due to geometric constraints, and is incompatible with modern highway use and the need for conveyance of heavy equipment and fire equipment. Projects to widen the existing bridge or increasing its vertical clearance are technically infeasible. The overall sufficiency rating based on a July 15, 2014 inspection by Caltrans Structure Maintenance and Investigations was 13.3. The bridge is considered deficient due to its age, deteriorated condition, elevated maintenance costs, and seismic susceptibility.

The truss structure has repeatedly been struck and damaged by oversized vehicles. Several main truss members and portal cross frames have been replaced, typically with plug welding. The truss portion of the bridge was last painted in the mid-1970s. The County does not have funding for a bridge painting program. The maintenance needs of the bridge are high due to its age, design, and materials of construction.

The County proposes to replace the bridge with the objective of providing a bridge that meets modern highway standards and can serve the local and regional transportation needs. The proposed project will replace the existing single-lane steel truss bridge with a new two-lane bridge. In addition, the roadway approaches on both ends of the new bridge will be widened to accommodate two 12-foot wide lanes, 4-foot wide shoulders and 3-foot wide unpaved shoulders.

Humboldt County Public Works retained Morrison Structures, Inc. to prepare a Bridge Type Selection Study (January 2013) to assist in the County’s selection of bridge type for a replacement bridge. Morrison Structures developed the type selection study based on using the existing alignment and providing a clear roadway width of 26 feet (two 12-foot travel lanes with two two-foot shoulders). The County has not made a determination on the design type for the new bridge. This decision will be made during the preparation of the Environmental Impact Report for compliance with the California Environmental Quality Act.

Construction is expected to require two seasons due to the amount of work to be performed and the limited allowable work period. Foundations and support walls for a new pier (or piers) and the south abutment would be constructed in the first season. This will require water diversion and excavation of channel sediment. A detour would not be required during the first season. Detour construction, dismantling and removal of the existing bridge, and construction of new piers, abutments, superstructure, and approaches would be performed during the second season. Work during the second season will require erection of falsework and temporary support bents. 

The detour road will be built over a low water crossing on the Mattole River, approximately ½-mile downstream from the bridge. The existing bridge will be dismantled using a crane to remove the steel truss sections and excavators with demolition tips to break apart the piers and abutments. The existing bridge pier in the river channel and both abutments will be completely removed and pile supports will be excavated and cut off at a minimum of 5-feet below the surface. All bridge, abutment, and pier debris will be removed from the streambed using heavy equipment.


Draft Environmental Impact Report and Environmental Assessment (Joint EIR/EA)

  • Project related documents, studies and reports available upon request.