Earlier this month Caltrans, after conducting a procedural public hearing, posted a 10 mph speed limit for the Oak Grove Bridge on the Mineral King Road. The 1923 multiple-arch concrete structure has been determined eligible for inclusion in the National Register of Historic Places.
Reed Schenke, Tulare County’s chief engineer of Public Works, in an update he presented to the Tulare County Planning Commission on Wednesday, Sept. 28, said the lower speed limit will cause less oscillation of the aging structure.
“Of the more than a dozen bridges in the county that are at least 50 years old and in need of retrofitting, the historic Oak Grove is the most recognizable,” Schenke said. “Among the backlog of projects, most of the bridges are either functionally obsolete [too narrow for volume of traffic] or structurally deficient [unsafe]. The Mineral King Road bridge is both obsolete and structurally unsound.”
Currently, the State Historic Preservation Office is reviewing construction alternatives and will recommend a preferred alternative based on the structure’s historical significance, Schenke said.
Three alternatives have been proposed for the project:
—Full replacement on the current alignment,
—Chip away existing materials and repair and replace structural elements, or
—Retain the old bridge for pedestrian access and build and realign a new structure.
Schenke said Alternative 2 will most likely be the chosen alternative in terms of cost but would necessitate inspections and more repairs in the future. After a series of public hearings and certifying of the project’s documents, construction on the preferred alternative is expected to begin in the spring of 2020.