The technology, installed by lead bridge designer, AECOM, can assess damage following an earthquake. The reinforcing steel cages that strengthen the bridge’s 110-ft deep by 11-ft diameter major foundations include wiring placed into the structures that provides electrical feedback when signals are transmitted down the columns to identify any damage.
“It’s a mechanism by which after a very strong earthquake, engineers have a way to come out and use instruments to read the cabling systems in the columns to see if there has been any underground damage to foundations,” says Baker.
While unique technology helped deal with seismic issues below ground, the project team has been precariously working around a bustling freeway above ground.
Baker says throughout the project, crews have had limited access to the median, and hardly any room for material lay-down space.
“Working over an active freeway and keeping traffic safe has added a lot of complexity,” he says. “We’ve had to work a lot at night when we could close the freeway or reduce the number of lanes.”
As the bridge nears its December 15 completion, Lawrence Damore, Skanska project executive, says his biggest concern is that they stick to the schedule and overcome any unforeseen problems.
“One example will be to ensure that the restoration of the slope in the median takes place so that enough time is allowed for the placing of electrical conduit, the light fixtures, and then the landscaping,” says Damore. He says slope will require 613 scrapers, 5,000 cu-yds of dirt, and one big A JD450 dozer to get it stable again.
The 584-ft-long bridge is the first phase of the $735 million, 11.5-mi Metro Gold Line Foothill Extension light rail from Pasadena to Azusa. When complete, Skanska USA will hand the project off to Foothill Transit Constructors, a Kiewit Parsons Joint Venture, which was awarded the Pasadena to Azusa Alignment Contract.
This $486 million second phase is slated to finish in 2015 and includes construction of stations, tracks, crossings, bridges and all associated alignment work.