“It will be the most significant and costly project in the history of [Caltrans] District 10,” says Skip Allum, a spokesman for the district, which covers much of the northern San Joaquin Valley.

The 2,725-ft bridge structures on Interstate 5 provide access over the Stockton Channel for more than 130,000 vehicles a day. Trucks, many of which are going to and from the Port of Stockton, account for 19% of the traffic. 

The project has already received $532 million in allocated funding from the Road Repair and Accountability Act of 2017. Completion is scheduled for 2031. 

Kiewit won the pre-construction services contract, prevailing over rival bidders that included an American Bridge-Myers-Aecon consortium and Stockton Viaduct Constructors. As the design phase continues, Caltrans will have the option to award the construction contract to Kiewit or advertise the project for bids 

The original bridges were constructed in the 1970s using lightweight concrete decks that have deteriorated over the years, resulting in frequent repairs, freckled rust forming at various locations throughout the superstructure steel, damaged steel bracing, and cracking in the concrete retaining walls, bents, and columns. 

Another problem has been substructure deficiencies, such as soil liquefaction potentially caused by seismic activity. The current structures are not rated to accommodate permit loading, which is required for movement of goods. 

Caltrans identified the need to replace the bridges in 2014. The agency chose to proceed with complete bridge replacement in June 2021 after ruling out the alternatives of deck rehabilitation or superstructure replacement.

The complete replacement “meets the project’s purpose and need; it provides the greatest improvements to the existing structural deficiencies and allows for 15-axle permit loads, per current Caltrans Design Standards, to traverse the two bridges,” Caltrans said in an April 2021 report.