Third foundation completed for Gold Line Foothill Extension bridge

Here’s the email that went out this morning from Foothill Extension Construction Authority CEO Habib Balian on the bridge over the eastbound 210 freeway in Arcadia:

Early this morning, Skanska completed the last of three deep (110 foot deep, 11 foot diameter) foundations for the I-210 Bridge – a significant undertaking. 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 Midnight to 5:00 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.”

As discussed in this article, 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.

Skanska 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. Here is a link to a video that highlights the work to be undertaken in the next few months.

The Gold Line Foothill Extension will run 11.5 miles with six new stations between the Gold Line’s current terminus at Sierra Madre Villa in Pasadena and the Azusa/Glendora border. The project is funded by the half-cent Measure R sales tax increase approved by Los Angeles County voters in 2008.

3 replies

  1. I’m very happy to see the continued expansion of the Metrorail system. I’ve visited other nations, and our metro compares very favorably in many areas.

  2. This was a fascinating update on the construction of this project! I wish I could have been there to see the lowering of the cages. 110 feet is about the same height as a 9 story building!