Category Archives: FAQ Answered

Other than on movable bridge projects, when should a grid deck be considered?

Grid deck systems are often associated with movable bridges, which is not surprising because you won’t drive over many that don’t have an open steel grid deck, and you can’t miss the noise and ride quality they produce.  However, when you drive over a concrete filled steel grid or Exodermic bridge deck on a fixed span structure or newer movable bridge, you almost certainly won’t know it’s a grid deck because it has a top concrete surface just like a conventional reinforced deck.

As a comparison, by square footage, there has been 3-4x more concrete filled steel grid decks (including Exodermic) installed in the last 6-7 years as there has been open grid.   Concrete filled grid and Exodermic bridge decks are often used on truss bridges, suspension bridges, cable stay bridges, and even newer movable bridges for weight savings.  They are also used quite frequently on accelerated construction projects when speed of installation is of utmost importance.  These systems can be precast and installed in weekend, or even overnight closures to reduce the impact on motorists.  Here is a list of just a couple bridges that people may not realize have a concrete filled steel grid deck:

  • Mackinac Bridge, MI
  • Brooklyn Bridge, NY
  • Manhattan Bridge, NY
  • Walt Whitman Bridge, PA
  • NB South Grand Island Bridge, NY
  • Henry Hudson Bridge, NY
  • Mathews Bridge, FL

Aren’t grid decks noisy and unsafe?

Most grid deck systems are installed with a concrete roadway surface similar to a conventional cast-in-place rebar deck and therefore are typically unnoticed by motorists. However, open grid deck systems can be more noisy and lead to anxiety by drivers’ crossing over long span structures. Slip resistance often is a concern for open grid deck systems. Studies have shown that serrations on the top of the main bars improves traction and diagonal open grid decks are less prone to wheel tracking along the cross bars.