Replacement of the Kosciuszko Bridge Brooklyn Connector: An Integrated Design and Construction Approach-Paper

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The paper describes the geotechnical and construction approach used to build the Brooklyn Connector embankments for Phase I of the Kosciuszko Bridge Replacement Project. The work required placing up to 45 feet of fill and installing T-Wall retaining structures beneath and beside the active Brooklyn-Queens Expressway (BQE), which is supported on settlement-sensitive shallow foundations.<br /><br />Because settlement of the underlying granular soils could cause damaging differential movement in the existing viaduct, the design team refined soil stiffness estimates using cone penetration testing (CPT) and seismic measurements. A field settlement load test helped calibrate the relationship between shear-wave velocity and elastic modulus; the resulting parameters produced settlement estimates consistent with observed test results. Staged analyses predicted up to about 1.38 inches of total settlement and a maximum differential settlement of about 0.9 inches under conservative assumptions.<br /><br />Structural analysis found that the viaduct could accommodate the predicted movements, but its bent cap beams needed additional shear capacity. The team therefore designed a fiber-reinforced polymer retrofit to be installed before fill placement.<br /><br />Construction risks were managed through a redundant monitoring system, including automated total stations and roughly 500 reflective targets on bridge columns. Measurements were reviewed alongside fill heights and compared with predicted settlement trends. Construction hold points at each five-foot increment allowed the designer to assess performance and adjust operations before thresholds were exceeded.<br /><br />The integrated design, structural retrofit, and trend-based monitoring approach enabled embankment construction to proceed while maintaining the existing BQE in service, protecting structural integrity and public safety while reducing the likelihood of unexpected work stoppages.

Keywords

Brooklyn Connector

Kosciuszko Bridge Replacement

geotechnical engineering

embankment construction

settlement monitoring

cone penetration testing

T-Wall retaining structures

fiber-reinforced polymer retrofit

differential settlement

BQE viaduct