Robust ground improvement enables more resilient bridge for New Jersey commuters 

Client challenge

Built in 1908, the Raritan River Bridge provides the sole rail link between 17 of the 20 stations on the New Jersey Coast Rail Line. But the bridge experienced damage during 2012’s historic Superstorm Sandy, and New Jersey Transit officials knew it wasn’t resilient enough to withstand future harsh storms.

They planned to replace the bridge, incorporating materials and structural design elements — including a raised steel superstructure and reinforced concrete piers on drilled shafts — to better withstand ocean surge forces and saltwater immersion.

The project design team chose Haley & Aldrich to manage the subsurface exploration program because of our geotechnical expertise and similar experience on the nearby Victory Bridge.

Our approach

Our team characterized the underlying geotechnical conditions by advanced borings up to 200 feet deep and into the underlying weathered rock. The total drilling length exceeded 15,000 linear feet — a notable figure for comparable projects. We coordinated with the U.S. Coast Guard, railroad flagging crews, and a submarine communication line. We also produced the geotechnical data reports that served as a basis for engineering analyses and contractor bidding.

We found that — because of weak, compressible organic soils and other factors — standard construction approaches would be too slow. To achieve acceptable performance and bring more certainty to the schedule, our designs included a staged railroad preload and surcharge program and a load transfer platform supported by continuous flight auger piles. We also developed an instrumentation and monitoring program to track the progress of the ground improvement as well as the state of existing train tracks. For stability, our deep foundation design for the retaining walls consisted of driven pipe piles, and the catenary structures and equipment and signal platforms were designed with drilled shafts.

Value delivered

• Guided the delivery of a bridge that will better withstand extreme weather and minimize service disruptions
• Developed design elements that would keep the project on schedule despite challenging soil conditions
• Developed an instrumentation and monitoring program to protect existing train tracks during work