The Humboldt County Department of Pubic Works has received a new engineering assessment of the Brookwood Covered Bridge in Jacoby Creek, which recommends that the County continue to maintain the existing bridge into the foreseeable future, rather than replace it outright.
The assessment concludes: “At this time, continued maintenance of the bridge appears to represent a greater return on the investment of public works funds compared to an outright replacement of the bridge”.
Based on this assessment, the County will explore funding options for performing necessary repairs so as to maintain this unique bridge in a serviceable condition over the long-term. The option of replacing the bridge with a more modern structure will be tabled indefinitely.
The Brookwood Covered Bridge was built by local residents in 1967. Concern over the fate of this scenic, one-lane wooden bridge erupted last May when community members learned that the Humboldt County Department of Public Works had been awarded a federal grant which would provide 100% funding to replace the bridge with a more modern design.
Public Works had sought the funding to allow the Department to explore options for the long-term future of this bridge. By obtaining funding first, the County can be assured of being able to move forward with replacement, should that prove necessary.
Following an initial community meeting at the bridge arranged by local residents, the County hired Quincy Engineering, a consulting firm with specific expertise in wooden bridges, to review and provide updated information on the status of the existing bridge, provide maintenance work recommendations and costs and compare the costs of maintaining the existing structure over time versus replacing the structure at this time.
Quincy’s Bridge Condition Assessment and Load Rating Analysis notes that the Brookwood Bridge was well-designed and constructed by the standards of its day, but that it does not meet current standards for structural capacity or design criteria. The assessment cites a 2011 bridge inspection report by CalTrans which gave the Brookwood Bridge a sufficiency rating of just 37.7 (out of a possible 100) and classified it as “Functionally Obsolete” due to its one-lane design.
However the assessment goes on to note that the bridge is “generally in good condition”, due in part to continued, ongoing maintenance and repair by the County, including replacing rotting and deteriorated timbers as well as replacing roofing and rotting guardrail posts. The load-rating analysis also finds that while the bridge cannot carry modern design loads, it does have adequate capacity to service the current levels of traffic.
The assessment also outlines a number of repairs that will be necessary in the near term, including powder post beetle eradication, repairing pedestrian railways and walkways, replacing rotted approaches and guardrails and protecting exposed steel parts from corrosion. The report provides an estimate of $398,000 for this needed rehabilitation work, noting “Although the bridge is generally in adequate condition, it does require a relatively higher level of maintenance on behalf of the County due to the nature of its timber construction which is more vulnerable to decay and deterioration than other bridge materials such as concrete and steel.”
The assessment concludes: “In general, the existing bridge is in good to fair condition. It has adequate structural capacity to carry the current level of anticipated vehicular loading. However its timber construction is subject to deterioration through exposure to moisture and fungus, attack from boring insects, and traffic wear. In addition, there is boring insect activity inside critical structural members (lower chords) that should be treated and arrested as soon as possible to preserve existing structural capacity. It should also be anticipated that the County will be required to continue to repair and replace portions of the members at the current or increased level of maintenance efforts in the foreseeable future. At this time, continued maintenance of the bridge appears to represent a greater return on the investment of public works funds compared to an outright replacement of the bridge.”
Based on this analysis, the County will be exploring options for funding sources to do the necessary repairs and maintenance to extend the life of the current structure as long as possible. The option of replacing the bridge with a more modern structure will be tabled indefinitely.
Copies of the Bridge Condition Assessment and Load Rating Analysis can be had by contacting Chris Whitworth, Deputy Director of Public Works, at 445-7377 or firstname.lastname@example.org.