GRS Bridge Abutment

The challenge

The Hamilton County Highway Department required four bridges be replaced.  The County wanted to engage in innovative construction of its infrastructure.  Downtime of the bridges needed to be minimized to reduce impact to residents.  The Federal Highway Administration (FHWA) standard for Geosynthetic Reinforced Soil (GRS) in an Integrated Bridge System (IBS) needed to be updated to allow consideration for alternate products.  Alternate products would provide options for the county to save cost and reduced construction time. 

The solution

Hamilton County, the engineering firms and Reading Rock consulted with the FHWA to educate and implement the modification of the construction techniques and standards to identify Allan Block Segmental Retaining Wall (SRW) units as an approved product.

Allan Block units met specification requirements and were installed in conjunction with Strata GRS 4800 and GRS 7200 geotextile product that reduced construction time to weeks versus months.  By constructing a GRS-IBS system using SRW units, there was no need to install deep foundations or to pour concrete such as footings, abutments or wing walls, again reducing time and overall costs of the project.

The results

Hamilton County delivered a savings to its tax payers across all the bridge projects.  The reinstallment of the bridges was completed within the strict time constraints.  Additionally, the installation of the SRW system reduces future maintenance costs.  Aesthetically the abutment is attractive.  The entire system is flexible and coherent, all moving with the induced forces reducing the traditional “bump” drivers experience at each crossing.  

GRS-IBS system allowed for the utilization of on-site soils which greatly reduced impact on the local environment.  The GRS-IBS system will also work to prevent future soil erosion and undermining of the bridge structure.

Nationally, the FHWA continues to realize structures are built better, faster and for less by using a GRS-IBS system.  Under the “Every Day Counts” initiative, dollars spent are kept within the local government providing significant cost savings.  Local communities are able to improve the safety of their roadways with minimal financial impact to the residents.