Bespoke oscillator for Presidio Parkway

摘要

To complement the Presidio Parkway's picturesque setting, the project's new high viaduct bridge was designed with fewer columns and wide spans to open views to the San Francisco Bay and surrounding area. To support the bridge columns, giant foundations are being set deep into the ground. In order to dig the 3.65m diameter foundations a custom-made 3.8m Leffer oscillator machine was purchased by Malcolm Drilling. The 80tonne oscillator was used to twist giant, 3.65m wide steel casings, some to a depth of over 60m, through unstable ground conditions. These permanent casings form large foundation piles and are filled with reinforced concrete to create the seismically safe bridge foundations.