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Geotechnical Services for New Jersey Route 18 Freeway

Dynamic compaction was performed with 20-ton weights dropped from heights of approximately 50 feet.
  • A stable roadway subgrade for New Jersey, Route 18 Freeway--Gannett Fleming.

    Deep dynamic compaction of the Tinton Falls Landfill beneath Route 18. 

New Jersey Department of Transportation

Eatontown, New Jersey

Our Role
Final Design, Lighting Design, Geotechnical Services, Soils Program, Value Engineering.

New Construction
  • Dynamic compaction of the Tinton Falls landfill beneath the embankments
  • Preloading and surcharging the embankments
  • Pile foundations for structures.

Gannett Fleming designed a 1.5-mile section of New Jersey Route 18 through Eatontown, which was known as the freeway’s missing link. This section of Route 18 connects the western and southern portions of the freeway and provides connector roadways and ramps directly to Route 36. The project includes eight new bridges on curved alignment and 11 new ramps. 

The project included the construction of seven 20- to 40-foot-high, roadway embankments, as part of the interchange with the Garden State Parkway. The embankments are located across a 25-foot-deep landfill containing mostly household trash.

What We Did

Gannett Fleming was responsible for all final design, including the preparation of right-of-way and construction plans, specifications, and cost estimates. The design included the soils program, lighting, signing, traffic control, erosion control, utility relocation, and permits. 

Where New Jersey Route 18 crosses the Tinton Falls Landfill, deep dynamic compaction was determined to be the most cost-effective approach to densify the landfill material, as well as provide a fairly high level of certainty that excessive settlement would be eliminated. Dynamic compaction was performed with 20-ton weights dropped from heights of approximately 50 feet. Very deep craters were the norm for the project. In many instances crater depths reached eight feet or more. The craters were backfilled with sand prior to performing a low-energy or ironing pass. 

Key Features

  • Extensive studies, including value engineering, archaeological, and environmental considerations
  • Design of two 1,100-foot viaducts over the Garden State Parkway
  • High-mast highway lighting in the central area of the interchange
  • Noise walls at specific locations in consideration of local residential communities
  • Staged construction that would open new ramps to Route 36 midway through the construction schedule.

Sustainability Features & Outcomes

  • Special consideration was given to preserve wooded areas and vegetation in their natural state with minimum areas used for highway construction 
  • In order to mitigate any potential impacts, all affected areas were replanted with grass and native trees to blend with its surroundings  
  • Noise walls were utilized at certain residential and apartment areas.

Awards & Recognition

  • Globe Award, 2005, Transportation Development Foundation, American Road & Transportation Builders Association Globe Awards
  • No. 3 Roads, 2005, Roads & Bridges, Top 10 Roads 
  • Project of the Year award, 2006, American Society of Highway Engineers, Outstanding Highway Engineering Awards
  • Honor Award, 2006, American Council of Engineering Companies of New Jersey Engineering Excellence Awards.

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