Early Oct. 7, the last of three 110-foot deep, 11-foot diameter foundations for the I-210 bridge was completed, according to Habib Balian, CEO of the Metro Old Line Foothill Construction Authority.
<Story continues below the following 5-minute video showing work on the bridge and traffic detour plans on the 210 Foothill Freeway.>
Each deep hole was reinforced with 60-ton steel cages that had to be brought to the site in two large segments and permanently joined on-site. Once lowered into place, close to 450 cubic yards of concrete was poured into each reinforced hole – requiring 45 truck-loads of Irwindale-produced concrete. Most of this work was done late at night, from 12 midnight to 5 a.m., requiring multiple closures of the eastbound I-210 Freeway and coordination with Caltrans, CHP, City of Arcadia Police Department, and others.
In addition to the fact that the amount of steel used in the three reinforcing steel cages is enough to circle the Santa Anita main racetrack three times, it is also interesting to note that what is intertwined into that steel makes each column “smart,” Habib explains. Wires were embedded into each reinforcing steel cage capable of sending electrical impulses through the foundation’s structure. In the event of an earthquake, these impulses will be utilized to identify if any damage has occurred to the foundations. This technology, called Time Domain Reflectometry, has been utilized in landslide prone areas to detect earth movement and is being used for the first time in a bridge with this project. Without this state-of-the-art technology, the only way to check the impact of an earthquake on the foundations would be to physically excavate them.
Builders Skanska USA will now focus on building the bridge abutments, or the ingress/egress points to the bridge on either side of the freeway. They will also start work on the three iconic, basket-themed columns (being built above the three deep foundations) that are certain to become the hallmark of the gateway bridge. — By Scott Hettrick