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NJDOT Builds First Orthotropic Deck in New Jersey


Overview

  • Roadway improvements of two 12’ lanes, one 12’ auxillary lane, and 8-10’ shoulder all on both sides.
    • Will also include an 8’ median barrier to separate opposing traffic.
    • 6’ sidewalk, will accommodate pedestrian and bicycle traffic.
  • Improved vertical clearance of 70’ when closed compared to originally 35’.
  • 135’ vertical clearance when raised will remain.
    • Reduced opening & closing by 75%.
    • Will result in reduced delays and disruptions to traffic.

What is an Orthotropic Deck?

  • Steel Orthotropic Deck
    • Developed in Germany in the 1930’s, similar to United States (U.S) Battleship decks.
    • A thin steel plate has a series of longitudinal “ribs” and floor beams, wearing surface.
    • 100% steel superstructure.
    • Can see same principles on everyday level with some types of cardboard.

      Steel Orthotropic Deck design image

Why is it being used?

  • Pros
    • Prefabricated in a shop, which results in faster construction and higher quality control.
    • Lightweight, which is a critical characteristic for movable bridges.
    • A lighter weight allows the bridge to be more efficient, and also allows for faster operation.
      • Since the bridge is more efficient, it will require less maintenance, which will reduce lifecycle costs.
    • Highly redundant system; minor cracking is often just a nuisance rather than a serious structural threat.
    • Allows for longer span lengths, which provides a better riding surface than others since it contains less connections.
    • Good cold weather constructability, since there is not a temperature requirement for concrete to cure.
    • Corrosion resistance has historically been very good, partially from wearing surface and closed ribs.
  • Cons
    • Unique challenges in terms of design and fabrication because of very complex welds.
    • Up to this point, not very standard or common in the United States.
    • Higher initial fabrication cost, but offset in the long run since less maintenance costs.

Research with Lehigh University

  • Examined Prototypes of Verrazano-Narrows, Williamsburg, Bronx-Whitestone bridges (All in New York).
  • Done to understand and analyze how they perform.
  • Orthotropic decks are the only deck that can achieve a 100 Year Design Life, according to Dr. John Fisher.
  • NJDOT looked at prototype for this deck with Dr. Sougata Roy.
    • Examined 3 different connection options.
    • Overall successful performance.
    • Also determined critical stresses and load distribution.

Manufacturer

  • Oregon Iron Works-Vigor is manufacturing the deck.
  • Expected to be completed in 2017.
  • Transferred in 5 pieces for 1 month by ship.
    • Shipped in 5 pieces to avoid extend closures, as less risk of delays since less field work required
  • Coast Guard says channel (Hackensack River) can be closed for a max of 21 straight days.
    • Erection process expected to last 14 days.

Where else are they?

  • Utilized successfully for thousands of bridges worldwide (Mainly in Europe, Asia, and South America)
  • “Up and Coming” type of bridge deck in the U.S. today; approximately 100 in the U.S.
  • Golden Gate Bridge (California, Replacement of concrete deck in 1985 with an orthotropic deck)
  • Bronx-Whitestone Bridge (NY) , Verrazano-Narrows Upper Deck (NY) (Orthotropic used as replacements)
  • New decks on Tacoma Narrows Bridge (Washington), Alfred Zampa Memorial Bridge (California)
  • Many movable bridges in Alaska as well constructed with orthotropic decks
 
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  Department of Transportation
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  Trenton, NJ 08625-0600
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  Last Updated:  May 25, 2017