Case Study: Unexpected Soil Conditions Causing Delay on New Jersey Turnpike Widening (New Jersey, 2017)

Project Overview
• Name: New Jersey Turnpike Widening Project
• Location: Northern New Jersey
• Year: 2017
• Project Size: $1.2 billion
• Scope: Widening of interstate highway including embankments and bridges
• Lead Agencies/Contractors: New Jersey Department of Transportation (NJDOT) /

Category of the Issue, Problem, or Challenge
• Geotechnical
• Differing Site Conditions

Summary of the Issue, Problem, or Challenge
Unexpectedly soft and compressible soils were discovered during excavation, necessitating redesign of embankment foundations and additional ground improvement works.

Root Cause Analysis

• Incomplete geotechnical site investigation and sampling prior to construction.
• Overreliance on historical soil data without adequate exploratory borings.
• Failure to anticipate variability in subsurface soil conditions along the corridor.
• Insufficient contingency planning for differing site conditions.

Impacts Due to the Issue, Problem, or Challenge

• Project delay of 6 months due to design revisions and additional ground improvement.
• Increased costs for additional materials, equipment, and labor.
• Impacted overall project schedule and stakeholder confidence.

Corrective Actions Taken

1. Conducted extensive additional soil borings and testing to characterize subsurface conditions.
2. Redesigned embankment foundations incorporating deep soil stabilization techniques.
3. Improved pre-construction geotechnical investigation requirements for future projects.
4. Implemented contractual provisions to address differing site conditions proactively.

Lessons Learned

• Thorough geotechnical investigations are critical to identifying site variability.
• Historical data should be supplemented with detailed, current site explorations.
• Contingency planning for differing site conditions mitigates risks and delays.

Audit & Prevention: Project Control Questions to Ask on Future Projects to Help Control the Situation

• Are comprehensive soil investigations completed before construction?
• Is variability of subsurface conditions accounted for in design and planning?
• Are contractual terms clear regarding differing site conditions?