Installing Drilled shafts for the Magnolia Avenue BNSF RR Grade Separation
The Magnolia Avenue BNSF RR Grade Separation project involved separating the current grade at Magnolia Avenue crossing by raising the roadway over an active BNSF railroad line and constructing a 1,400-foot bridge to improve the traffic flow. The work happened right in the center median of Magnolia Avenue with active pedestrian and vehicle traffic and adjacent to active railroad tracks.
Malcolm Drilling was contracted to install 18 drilled shafts to support the new bridge. The shafts were 13 feet in diameter with an average depth of 92 feet. To optimize the design and compensate for the high axial load demands, 7 shafts were base grouted. The base grouting was accomplished by a combination of base plate and tube-a-manchette grout piping assembly attached to the pile reinforcing cage. All shafts were constructed under the use of polymer drilling fluid due to the high groundwater table. Malcolm Drilling used a large crane with a crane mount drill unit to provide enough clearance and stability for the 13-foot diameter shaft. Each shaft was tested using Gamma-Gamma Logging through 14 inspection tubes to verify shaft integrity. All work was performed under extremely tight access and required unique job site planning and staging.