The California Incline: DYWIDAG Soil Nails stabilize a Bluff at an important Coastal Road in Santa Monica
The California Incline in Santa Monica near Los Angeles, originally designed as a walkway in 1896, was cut through the bluffs to provide access to the local beach. In 1930, the path was widened to create a 426.7m (1,400ft) long road for vehicle use. The road also includes a 213.4m (700ft) long reinforced concrete bridge built in 1939. Since then, the road has been the major artery connecting the Pacific Coast Highway and Ocean Avenue, which leads into the center of Santa Monica.
After 85 years of heavy traffic, the California Incline was identified as structurally deficient. Consequently, the section is now being completely rebuilt and made seismically resistant. The old bridge with transverse concrete girders will be replaced by a new bridge that is being built in the same location.
The new structure consists of a pile-supported reinforced concrete slab structure. At a width of 15.8m (51.8ft), the new bridge deck is wider than the old one and accommodates additional sidewalks and bicycle lanes.
Within the scope of this project, the eroding bluff that extends 30.5m (100ft) above the incline roadway grade had to be stabilized for the long term.
For this purpose, 1,000 double corrosion protected (DCP), 32mm Ø, 75ksi DYWIDAG Soil Nails were anchored in the stable layers of the steep coast. A total of 15,850m (50,000ft) of DYWIDAG THREADBAR® with a net weight of 110t was used for soil nail fabrication.
Most of the DYWIDAG Soil Nails that were up to 22.9m (75ft) long were installed using high reach drill rigs and a crane-suspended work platform. Even with the challenging access conditions, the subcontractor Malcolm Drilling managed to meet the target schedule by successfully installing all of the DYWIDAG Soil Nails. To minimize visual impact, each nail head was cut off behind the slope face and patched with colored grout to match the surrounding soil.