The Route 58 Overhead is an essential component of a large construction project that converted a two-lane conventional highway into a four-lane expressway and eliminated an at-grade railroad crossing in Kramer Junction, CA.
The owner's request for Qualifications Fact Sheet for this project's construction manager general contractor contract states, "This project will address the need to safely accommodate the increase in large truck and recreational vehicle traffic and reduce current delays encountered by the traveling public. The project will reduce traffic congestion, provide limited access control, improve traffic safety, improve operation efficiency and reliability of goods movement, and reduce people/goods movement conflict."
During the material selection process, precast prestressed concrete girders and bulb tee girders were determined as the preferred construction method and cross-section. Con-Fab California, LLC collaborated with the contractor to develop the design, budget, and scheduling efforts by sharing design and construction data from similar highway projects they had successfully executed.
There was pressure to install the frame two segments on a tight schedule. Meeting construction milestones was impacted by a railroad moratorium in place throughout the 2018 fall and winter holiday season, which added an additional challenge. The 50 bridge girder segments comprising three spans of frame two in both viaducts were installed between September 18 and October 1, 2018. The 50 girders and girder segments comprising the two spans of frames one and three in both viaducts were installed between May 1 and May 13, 2019, also using only ten daylight work shifts owing to precast, prestressed concrete's inherent accelerated construction advantages.
Precast, prestressed concrete bulb tee girders were utilized in multi-span, multi-frame twin viaduct structure. The right bridge's two-span end frames were constructed with precast girders designed as conventional simple spans between supports for the structure's dead load with live load continuity. The span sizes of these frames ranged from 105 to 120 feet, The two-span end frames of the left bridge (157' and 140 spans) and the three-span center frames of both structures were constructed as girder segments erected onto substructure supports and shoring towers. The spans were subsequently made continuous with two-stage post-tensioning.
This project incorporated a critical grade separation that achieved community goals of significant safety improvements by eliminating at-grade railroad crossings and enhancing commercial goods' movement.
The traffic congestion of idling cars and trucks, which stretched for miles in each direction, has been eliminated, having a substantial positive impact on the environment due to the reduction of pollution and fuel waste.
The precast structure's bulk was less than what a cast-in-place post-tensioned box girder system might have offered. The lighter structure reduced foundation design cost and significantly improved design performance in a high seismic activity area. Utilizing precast, prestressed bridge girders, the general contractor successfully completed the project with limited effect on the environment and with minimal impact on the railroad operating envelope while maintaining cost and schedule efficiencies.