SCH Number 2026031253

Project Info

Title

National Trails Highway at Bridge 85 (Lamego Ditch) Replacement Project

Description

The Project includes the demolition of the existing timber bridge and its replacement with a concrete bridge designed to American Association of State Highway and Transportation (AASHTO) standards for two-lane concrete bridges, guardrails, guardrail end treatments, and approaches. The replacement bridge would accommodate two 12-foot-wide lanes, two 3-foot-wide shoulders, and two 2-foot-wide railings. The alignment would remain unchanged; however, up to 800 feet of pavement improvements on either side of the bridge may be needed to conform to the existing roadway vertical profile. Grading within the existing channel around the bridge may be needed to ensure sufficient storm conveyance and drainage of the area. A temporary, parallel road realignment, also referred to as a “shoo-fly detour”, would be constructed at each bridge location to accommodate through-traffic during construction. The proposed Project is needed to meet current bridge structural design and safety standards. To view your submission, use the following link. https://ceqasubmit.lci.ca.gov/Document/Index/331799/1Through the years, the bridge has been modified by various maintenance and repair work to maintain public safety and extend the service life of the bridge. The proposed replacement will resolve existing bridge deficiencies. The existing two-lane bridge will be replaced with a concrete bridge designed to American Association of State Highway and Transportation (AASHTO) standards for two-lane concrete bridges, guardrails, guardrail end treatments, and approaches. The existing soil is sandy and susceptible to scour, so pile extensions would be utilized, and the abutment foundation would be designed for scour. Additionally, rock slope protection will also be utilized to prevent scour. The bridge barrier would be a Type 85 concrete barrier with bicycle railing painted white, which is approved by the Manual for Assessing Safety Hardware and best matches the original railing. The bridge may be lengthened as needed to convey the storm flows. The replacement bridge would accommodate two 12-foot-wide lanes, two 3-foot-wide shoulders, and two 2-foot-wide railings. The vertical profile of the bridge will remain close to the existing profile, unless it is determined that additional vertical clearance is required to provide sufficient water conveyance beneath the bridge. It is anticipated that any necessary changes in vertical profiles would be three feet or less, with the elevation gradually conforming to the existing roadway elevations. The NTH is posted at a speed limit of 55 miles per hour. The alignment would remain unchanged; however, up to 800 feet of pavement improvements on either side of the bridge may be needed to conform to the existing roadway vertical profile. Grading within the existing channel around the bridge may be needed to ensure sufficient storm conveyance and drainage of the area. A temporary, parallel road (also known as a “shoo-fly”) would be constructed at the bridge location to accommodate through-traffic during construction. This parallel road may require placement of a culvert with rock slope protection. Based on weather conditions and construction activities, it is possible that there could be intermittent closures of the temporary parallel road. The temporary parallel road, including any culvert or rock slope protection, would be removed once construction of the replacement bridge and roadway approaches is complete. Construction of the replacement bridge would be completed within one year.

2 documents in project