I-95 NB & SB Rappahannock River Crossing Projects

Located on one of the state’s most congested highways, the Virginia Department of Transportation’s SB and NB Rappahannock River Crossing projects increased capacity on about 6 miles of I-95 near Fredericksburg. These design-build projects, which added three lanes in each direction, included two new 1,200 ft long, three-span bridges crossing the Rappahannock River (constructed within the median and parallel to the existing bridges); three replacement and widened bridges over Route 17; and one new bridge over Route 17. Schnabel took a holistic approach by collaborating with all engineering disciplines and the contractor to find optimal solutions to every project challenge. New lanes and bridges were opened ahead of VDOT’s anticipated schedule and both projects were delivered on budget.

These major projects increased capacity by adding collector-distributor (CD) and general-purpose (GP) lanes to the corridor. Schnabel provided innovative plans to address the time-of-year restrictions associated with drilling within the Rappahannock River, and to limit the geotechnical risk associated with cut slopes in the Potomac Formation (stiff fissued clays). These solutions addressed long-term and differential settlement concerns for the four bridges over Route 17 with minimal impacts to the construction schedule. The excavation of problematic acid-sulfate soils was avoided. The team also made remediation recommendations for unsuitable soils using chemical stabilization.

Geotechnical items on this project included shallow foundations (footings on IGM, footings on rock) and deep foundations (driven piles and rock socketed piles), rock excavation, MSE walls, noise barrier walls, critical cuts and fills (settlements and stability), earthwork, stormwater management basins, large diameter pipes, subgrade stabilization, and pavements. Design recommendations were developed considering historically available information, subsurface data provided by VDOT, and Schnabel’s subsurface exploration, which involved SPT borings, CPT and DMT soundings, hand augers, pavement and rock cores, falling-weight deflectometer (FWD) testing, and ground penetration radar (GPR).

The SB project was completed in May 2022 and the NB project was completed in May 2024.