North Avenue Bridge: Instrumentation, Monitoring, and Integrity Testing in a Live Urban Rail Environment
The North Avenue Bridge project is part of a broader effort to modernize critical rail infrastructure, replacing historic masonry arches with a new bridge designed to support increased freight and passenger rail demands. Construction took place in a highly constrained urban corridor, directly above and adjacent to active Amtrak, CSX, and MTA rail lines, requiring continuous coordination to maintain uninterrupted rail and vehicular traffic throughout the work.
As an ADSC Technical Affiliate, Foundation Test Group (FTG) collaborated with A.H. Beck to provide inspection and monitoring services supporting the construction of deep foundations for the reconstructed bridge. FTG’s role focused on verifying that drilled shafts were constructed to the proper depths and met project-specific tolerances required to satisfy the bridge’s structural design criteria.
To confirm drilled shaft integrity, FTG’s non-destructive testing teams performed Cross Hole Sonic Logging (CSL) on each shaft. CSL testing was used to verify concrete quality and identify any voids, defects, or inclusions that could compromise performance. This testing provided confidence in foundation integrity while allowing the project team to address potential issues early in the construction process.
In parallel with integrity testing, FTG was responsible for the design, installation, and monitoring of a comprehensive geotechnical instrumentation program, led by Geotechnical Engineer Nick Youngs, P.E. Instrumentation was deployed to monitor the structural integrity of both the existing and new bridge elements and to provide early warning of potential ground movement or structural response that could impact active rail operations beneath the bridge.
The instrumentation program included convergence nodes and track monitoring devices within tunnel areas, as well as tiltmeters, survey prisms, and vibration monitors installed on the existing bridge and surrounding structures. A GeoLidar scanning system was also deployed to monitor wall and tunnel movement, providing high-resolution, real-time data to support informed decision-making throughout construction.
This integrated approach to inspection, non-destructive evaluation, and real-time monitoring highlights the importance of collaboration and data-driven oversight on complex infrastructure projects. In dense urban environments with aging infrastructure and live transportation corridors, combining CSL testing with comprehensive geotechnical instrumentation plays a critical role in managing risk and supporting safe, efficient construction.
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