Hardin Flat Road is a low-ADT, rural local road that serves the public as well as users of Berkeley Camp.
MGE was the prime consultant to provide construction management services for the project that replaced a 5-span, timber bridge with two stringer approach spans, and a braced timber frame carrying the three center stringer spans, all supporting a concrete deck. The bridge superstructure and substructure, as well as the right Abutment 6 wingwall were all damaged in the RIM fire. The “Structurally Deficient” bridge was replaced with a clear span, cast-in-place post-tensioned concrete box girder bridge, approximately 120 feet in length by 28.5 feet in width.
Bridge Removal and Falsework Installation: A temporary debris catchment was suspended below the existing longitudinal timber stringers to prevent debris from entering the channel during deck removal. Using backhoes, dump trucks, and a hydraulic crane stationed on the roadway surface, the existing two-lane 100-foot long 26-foot wide concrete deck timber bridge, timber abutments, and associated structures were demolished and disposed of off-site.
Construction of the new structure: Two concrete abutments were constructed on six 42-foot-long, 48” diameter CIDH piles. Concrete abutments were poured on site and required the excavation of approximately 240 cubic yards of concrete, soil, and rock. Excavated soil was used to backfill the abutments. Controlled blasting was used to excavate large boulders to facilitate abutment construction. The falsework is constructed on four bents, Bent 2 and 3 supported on the existing structure foundatations. The falsework is standard for this type of construction and conforms to the Caltrans Falsework Manual and contract specifications, 12-foot-tall wing walls were installed at all four abutment corners.
Project activities resulted in the removal of 14 trees with a diameter at breast height (DBA) greater than four inches. All vegetation scheduled for removal will be removed by hand or with hand tools. Mechanized vehicles will not be used to clear the brush or debris from the area. The project also has an identified prehistoric archaeological area that is defined with ESA fencing. Abutment excavations were observed by an archaeologist and a Native American Advisor. Utilities are also temporarily relocated. Coordination activities involved USFS, CDFW, Tuolumne and Yosemite Mi-Wuk Tribe, PG&E, AT&T, Berkeley Camp and their contractors, residents along Hardin Flat Rd, and the nearby Yosemite Lakes RV Park.