NO. 6 BRIDGE: Making History in California

Dec. 7, 2023
The San Gabriel River Bridge’s long closure was met with success

The Golden State is home to beautiful scenery, great weather, and monumental bridges. 

The San Gabriel Bridge is one of those bridges. However, when work needed to be done on the structure, The California Department of Transportation (Caltrans) District 7 had to make some first-time decisions to complete the major work scheduled on this project. 

The hinge and diaphragm of the structure needed to be repaired. This massive project required two 126-hour closures to complete, a first for the state in a transportation project. 

The team, composed of Flatiron, Caltrans, and the cities of Irwindale, Duarte, and Baldwin Park came together to take on this challenge, and make sure the project got done on time. 

Both bridge hinges were replaced during the summer of 2022. The first closure took place from July 20 through July 26 on the westbound lanes. The second closure took place from Aug. 10 through Aug. 16 on the eastbound lanes. 

Knowing time was of the essence, Flatiron prepared for the closures ahead of time by mixing concrete and developing a cement mixture with the proper setting time. Rapid-strength concrete was used instead of the typical method of pouring concrete that could take up to 28 days to set. Forward thinking was a key to completing this project in a timely manner. 

Flatiron had to experiment with 10 different batches before getting the correct ratio to optimize both the workability and strength. A mock-up bridge was constructed off-site to test the batch, and as the owner and stakeholders watched, the ratio worked, and the mixture was approved for use on the structure. 

Through dedication, coordination, and forward thinking, the project got done 16 days ahead of schedule earlier this year in February. Now, this vital artery is open and will be used for years to come. RB

Project: San Gabriel River Bridge Hinge and Diaphragm Repairs 

Location: City of Irwindale, Los Angeles County, California 

Owners: California Department of Transportation 

Designer: California Department of Transportation 

Contractor: Flatiron West, Inc. 

Cost: $18 million 

Length: 800 feet 

Completion Date: February 2023 

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