Harry Nice Bridge Geotechnical Instrumentation Case Study

Just an hour drive down MD 301 from National Harbor, construction to replace the Governor Harry W. Nice Memorial/Senator Thomas ‘Mac’ Middleton Bridge (HNB) began in spring of 2020. The Maryland Transportation Authority (MDTA) contracted with Skanska-Corman-McLean (SCM) to deliver a new US 301 bridge spanning 1.9 miles from Maryland to Virginia over the Potomac River aiming to improve capacity, safety, and access of the roadway. The project area presented a geotechnical design challenge due to the installation of new bridge foundations in the problematic soils of the Atlantic Coastal Plain alluvial deposits. With the existing bridge remaining in service during construction, and the site’s logistical constraints placing new pile driving operations near existing abutments and piers, a complex instrumentation and monitoring plan was developed to ensure public safety throughout the project. This paper discusses the geological conditions of the project area, the collaborative approach of various design team members to develop an appropriate monitoring plan utilizing various instrumentation, an understanding of baseline conditional movements of the existing bridge, and impact response of adjacent construction activity to help deliver effective new bridge foundations while protecting the old ones.