Harry Nice Bridge Geotechnical Instrumentation Case Study-Technical Paper Upload

Technical Paper Upload

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The Harry Nice Bridge replacement involved constructing a new 1.9-mile US 301 crossing of the Potomac River, less than 150 feet from the existing bridge, which remained open to traffic. Soft, compressible Coastal Plain soils and restricted construction access created risks that pile driving and embankment fills could move or damage the existing bridge and affect its foundations.<br /><br />A monitoring plan used more than 140 instruments to track structural and ground behavior. Equipment included robotic total stations and prisms, tilt and strain sensors, vibration monitors, crack meters, inclinometers, piezometers, and settlement plates. Preconstruction inspections and baseline monitoring helped the team distinguish construction effects from normal changes caused by temperature, traffic, weather, and other conditions. Remote monitoring and coordination among engineers and contractors supported timely responses despite difficult access and communications constraints.<br /><br />Over 2.5 years, monitoring showed no long-term impact to the existing bridge from pile driving or embankment construction. Vibration levels remained below the established alert threshold. At one Virginia abutment, nearby pile driving caused localized ground movement of up to 2 inches, but follow-up measurements showed no corresponding movement or rotation of the existing structure. A separate test confirmed that pile driving near freshly poured concrete remained within the vibration tolerance. Embankment settlement reached up to 6.5 inches in Maryland and 2.4 inches in Virginia, within expected design estimates; monitoring also supported decisions about surcharge removal and continued construction.<br /><br />The case demonstrates how targeted instrumentation, overlapping measurement methods, and continuous engineering review can manage construction risks and protect an aging bridge while maintaining public safety and project progress.

Keywords

Harry Nice Bridge

US 301 crossing

Potomac River

bridge replacement

construction monitoring

pile driving

embankment settlement

structural instrumentation

Coastal Plain soils

public safety