Construction crews are currently assembling giant steel girders for the new Pfeiffer Canyon Bridge on State Route 1 in Monterey County, CA. The new structure will replace the old span that was closed to pedestrian and vehicular traffic last February, after heavy rains caused a landslide under the structure damaging one of its main support columns.
The $24 million Accelerated Bridge Construction replacement project is being led by Golden State Bridge Incorporated of Benicia, CA. The project began in March and is expected to be accessible to the travelers in late September 2017.
The old bridge, which was built in 1968, was damaged beyond repair by the rains and had to be demolished. Engineers used a 6,000-ton wrecking ball and other equipment to strike precise points on the bridge to force it to break apart over week-long period.
To get a new bridge up on a tight stretch of Highway 1, the team is having massive steel girders trucked-in with a Highway Patrol escort and then assembled on site.
The girders are being fabricated in the nearby city of Vallejo, then painted in the city of Linden. There are a total of 15 girders, each weighing 62-tons and stretching 62 ft-long. They are arriving to the site in groups of three and are being assembled using splice plates and approximately 14 thousand bolts to connect them all together.
Once the girders in position, they will be launched or slowly moved across the canyon later this month.
"The unique challenge is the girders are of such a heavy weight and size that extreme caution and logistics must be followed to ensure a successful operation as we move these girders across Pfeiffer Canyon," says Caltrans Structural Engineer David Galarza. "Our goal is to be very deliberate to ensure that we do this the right way. We are also using heavy equipment within a confined space along Pfeiffer Canyon."
When complete, the new bridge will have a 310-ft-long span, about 100 ft above the canyon floor.
While Caltrans has built and rebuilt many bridges, the circumstances on this project are different, in that the damage was caused by a storm and a landslide. Experienced structure maintenance engineers who looked at the damage say this is the first time they have seen an actual support column of a bridge be displaced by a landslide.