National Trails Highway 30 Bridges Project

The San Bernardino County Department of Public Works (County), in coordination with the California Department of Transportation (Caltrans), proposes to replace 28 timber trestle bridges, one concrete box culvert, and one pipe culvert with concrete bridges on the National Trails Highway (NTH), formerly known as US Route 66. The National Trails Highway at 30 Bridges Project (Project) is located between the unincorporated community of Dagget to just east of Essex, in the County of San Bernardino. The existing timber bridges were constructed in the 1930s and span over man-made ditches or "flash flood washes". The timber bridges vary in length but share similar construction components. The typical timber trestle bridges are composed of simply-supported timber stringer spans with a laminated timber deck supported on timber strutted abutments and bents consisting of timber piles. The bridges are approximately 28-feet wide with guardrails that do not meet current safety standards. Through the years, the bridges have been modified by various maintenance and repair work with the intent of maintaining public safety and prolonging the service life of the bridges. Two bridges have been replaced – Signal Ditch Bridge currently consists of a pipe culvert and Blossom Ditch Bridge consists of a concrete box culvert. The proposed replacements will resolve existing bridge/culvert deficiencies. The existing, two-lane bridges/culverts will be replaced with concrete bridges designed to American Association of State Highway and Transportation Officials (AASHTO) standards for two-lane concrete bridges, guardrail, guardrail end treatments, and approaches. The existing soil is sandy and susceptible to scour, so pile extensions may be utilized at the piers and the abutment foundations. The bridge barrier would be a concrete barrier Type 85 with bicycle railing painted white which is Manual for Assessing Safety Hardware (MASH) approved and best matches the original railing. The bridge lengths would match the existing lengths, if possible, but would be lengthened as needed to convey the storm flows. Each 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 bridges will remain close to the existing profile except for those locations in which it is determined that additional vertical clearance is required to provide sufficient water conveyance beneath the bridge. It is anticipated that any such necessary changes in vertical profiles would be three feet or less, with the elevation gradually conforming to the existing roadway elevations. The National Trails Highway 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 each bridge may be needed to conform to the existing roadway vertical profile. Grading within the existing channels around the bridges 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 each bridge location to accommodate through-traffic during construction. Construction of each bridge replacement is expected to be completed in one season, limiting the time the detour would be in place to one season as well. Based on weather conditions and construction activities, it is possible that there could be intermittent closures of the temporary parallel road. Permanent acquisition of right-of-way is not anticipated; however, temporary construction easements may be needed to accommodate construction of the temporary detour routes. There are existing utilities which may require relocation as part of this project. Existing utilities may include an underground fiber optics line, overhead electrical line, telecommunications lines, water lines, and gas lines. All utility relocations would be included within the defined limits of the Project area. Typical equipment for roadway construction would include heavy construction earthmoving equipment, dump trucks and pavers. Typical bridge construction equipment would include cranes, pile drivers, drill rigs, excavators, concrete trucks, and concrete pumps. This Project is funded with a combination of local and federal funds. Caltrans is the lead agency responsible for completing National Environmental Policy Act (NEPA) compliance while the County is the lead agency responsible for completing California Environmental Quality Act (CEQA) compliance. Purpose The purpose of the Project is to replace structurally deficient bridges in order to: • Enhance safety on National Trails Highway by proving new vehicular crossings for thirty bridges; • Provide a transportation facility consistent with County and Caltrans Standards, as well as local and regional plans. Need Full replacement of the bridges/culverts is needed because the current structures do not meet structural design standards.