U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000


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Construction

GRS-IBS

What is GRS?

GRS–IBS is a form accelerated bridge construction (ABC) that lowers cost, slashes construction time, improves durability, and increases safety — all at the same time. For budget–challenged Federal, State, and local transportation agencies, that is a life-saver.

GRS–IBS technology uses alternating layers of compacted granular fill material and fabric sheets of geotextile reinforcement to provide support for the bridge. GRS-IBS also provides a smooth transition from the bridge onto the roadway, and alleviates the "bump at the bridge" caused by uneven settlement between the bridge and approaching roadway. The technology offers unique advantages in the construction of small bridges, including:

  • Reduced construction time and cost, with costs reduced 25 to 60 percent from conventional construction methods.
  • Easy to build with common equipment and materials; easy to maintain because of fewer parts.
  • Flexible design that’s easily modified in the field for unforeseen site conditions, including utilities, obstructions, existing structures, variable soil conditions, and weather.
GRS process step 1: Lay a row of facing blocks. GRS process step 2: Add a layer of compacted fill to the height of the facing blocks. GRS process step 3: Add a layer of geosynthetic fabric (reinforcement).

How Does It Work?

Rather than installing a deep foundation, this reinforced soil method builds up the substructure in a faster, simpler way. A GRS integrated bridge system is similar to a layer cake!

Step 1:  Lay a row of facing blocks.

How Does It Work?

Rather than installing a deep foundation, this reinforced soil method builds up the substructure in a faster, simpler way. A GRS integrated bridge system is similar to a layer cake!

Step 1:  Lay a row of facing blocks.

Step 2:  Add a layer of compacted fill to the height of the facing blocks.

How Does It Work?

Rather than installing a deep foundation, this reinforced soil method builds up the substructure in a faster, simpler way. A GRS integrated bridge system is similar to a layer cake!

Step 1:  Lay a row of facing blocks.

Step 2:  Add a layer of compacted fill to the height of the facing blocks.

Step 3:  Add a layer of geosynthetic fabric (reinforcement). Repeat until desired height is achieved.


What are the Benefits of GRS?

  • Reduced construction time and cost, with costs reduced 25-60 percent from conventional methods.
  • Easy to build with common equipment and materials; easy to maintain because of fewer parts.
  • Flexible design that's easily modified in the field for unforeseen site conditions, including utilities, obstructions, existing structures, variable soil conditions and weather.
  • Alleviates the "bump at the bridge" problem caused by uneven settlement between the bridge and the road.
  • Non-specialized labor -Typically a 5 person crew.
  • Built with simple machinery and hand tools.
  • Built with readily available materials.
  • Start-to-finish in days.

Publications:

Updated: 08/10/2015
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000