Bowman Road Bridge Defiance County Ohio

<figure id='attachment_8148' style='max-width:1396px' class='caption aligncenter'><img class="size-full wp-image-8148" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of the Completed Bowman Road Bridge." width="1396" height="1047" /><figcaption class='caption-text'> Figure 1. Completed Bowman Road Bridge. Source: Warren Schlatter.</figcaption></figure>Location: Defiance County, Ohio Owner: Defiance County Year Constructed: 2005 National Bridge Inventory (NBI) Number: 2039060 Crossing Type: Roadway bridge over stream Superstructure Type: Adjacent Precast Concrete Boxes Span: 79 feet Maximum Wall Height: 17 feet Maximum Wall Face Width (edge to edge): 34 feet Skew: 24 degrees Facing Type: Concrete Masonry Units (CMU) with split face (see figure 3) Average Daily Traffic (ADT) (when constructed): 345 Contract Type: Design-Bid-Build Unique Project Feature: The first GRS-IBS bridge in the nationBackground/Deployment: The Bowman Road Bridge, the focus of this case history, crosses Powell Creek and is in the southeast corner of Defiance County, Ohio. The bridge is approximately four miles south of the city of Defiance, the seat of the county. Despite experiencing a fairly low volume of traffic, Average Daily Traffic (ADT) volume of 345 vehicles per day, the Bowman Road Bridge is an important connection for local communities and provides an additional access route to the city of Defiance.<figure id='attachment_8149' style='max-width:1150px' class='caption aligncenter'><img class="size-full wp-image-8149" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Sketches of the project location. To the left, location of Defiance County, Ohio, to the right, location of Bowman Road Bridge." width="1150" height="575" /><figcaption class='caption-text'> Figure 2. (a) Location of Defiance County, Ohio and (b) Bowman Road Bridge. Source: Open Street Map, ESRI, FHWA.</figcaption></figure>Prior to replacement, the Bowman Road Bridge was located on a substandard horizontal curve that posed safety risks and limited vehicle speed. The Bowman Road Bridge was a truss bridge and its structure was in a failing state, which compounded safety issues. Given the safety issues, the Bowman Road Bridge required immediate replacement. However, due to lack of funds, replacement was not possible.Defiance County, the owner of Bowman Road Bridge, had to come up with a creative solution to replace the bridge in the most cost-efficient manner. Defiance County engineers had recently heard about Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS), a new, cost-effective bridge technology developed by FHWA, and decided to consider it for this project. GRS-IBS proved to be a good fit for the Bowman Road Bridge because the technology featured vertical abutment walls, as opposed to the longer slopes of traditional spill-through bridges, and could significantly reduce the superstructure’s span length. In the case of Bowman Road Bridge, a shorter span was preferable because it would cost less and better accommodate the curved alignment and superelevation. After carefully researching the GRS-IBS technology, Defiance County engineers were convinced to go ahead and construct the first bridge in the country featuring this technology.Project Challenges and Solutions: Many of the challenges Defiance County engineers encountered during construction of the Bowman Road Bridge replacement project were due to the fact that they were the first team in the country to build a GRS-IBS bridge. As pioneers working with GRS-IBS technology, Defiance County engineers did not have any resources to contact for construction advice. Rather, with the help of FHWA, Defiance County engineers had to resolve any issues on the spot. To streamline the process, Defiance County used their own in-house construction crews and equipment to construct the bridge abutments. The close collaboration between Defiance County’s engineers and construction workers provided an important knowledge sharing platform and was an integral component to the county’s success with GRS-IBS. The challenges listed below resulted from the Bowman Road Bridge and other GRS-IBS projects completed in Defiance County.<figure id='attachment_8150' style='max-width:439px' class='caption aligncenter'><img class="size-full wp-image-8150" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of Split face CMU block." width="439" height="361" /><figcaption class='caption-text'> Figure 3. Split face CMU block. Source: Every Day Counts (EDC) GRS-IBS brochure.</figcaption></figure>Constructing abutments from the channel Construction of the very first GRS abutment was started from the channel side. This method was chosen because it allowed for ease of access to both abutments. However, engineers and workers quickly realized that GRS abutments were more easily built from behind the walls (see figure 4). Building the GRS abutments from behind the walls allowed the construction crew to have more visibility since the workers could remain on top of the wall at all times. Another benefit of this construction method was that it allowed crews to avoid working in the channel, which is generally challenging and requires additional environmental permits.Determining an efficient crew size and equipment placement Once it was established that it was easier to construct a GRS abutment from behind the wall, it was necessary to determine the right crew size. The trial and error method revealed that the most efficient crew consisted of one excavator operator and four workers to lay out the wall. It was also determined that the excavator should be placed in the middle of the abutment with the materials strategically placed around it. This placement increased the efficiency of the crew by increasing accessibility, reducing excavator movements to only spinning in place, and allowing the excavator to stay in one position rather than moving across the abutment (see figure 4). Having an excavator bucket with a wrist, which allowed the bucket to be twisted, also increased efficiency. This configuration allowed the crew to pour the backfill stone out of the bucket corner, which made it easier to place the fill in corners and narrow openings.<figure id='attachment_8151' style='max-width:434px' class='caption aligncenter'><img class="size-full wp-image-8151" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of Five workers and a track-hoe excavator." width="434" height="309" /><figcaption class='caption-text'> Figure 4. Five workers and a track-hoe excavator. Source: Every Day Counts (EDC) GRS-IBS brochure.</figcaption></figure>To measure crew efficiency, Defiance County engineers and contractors measured the rate of block placement. During construction of the early GRS-IBS bridges, a rate of 200 to 300 blocks per day was considered efficient. Currently, given advances and increased familiarity with the process, Defiance County has tripled its productivity and can place about 1,000 blocks per day.135 vs 90-degree GRS wall angles The wing walls of the Bowman Road Bridge were at a 135-degree angle with the wall under the deck (see figure 1). This obtuse angle, combined with narrow walls under the deck, saved both backfill material and concrete masonry unit (CMU) blocks because it “cut off” the corners that would be needed if the walls were at a 90-degree angle (see figure 5). However, unlike 90-degree angles, obtuse angles required cutting blocks for a proper fit, which was very time consuming. The time and effort spent cutting the blocks offset any material cost savings associated with the use of 135-degree walls. Given these issues, 90-degree angled abutment walls were used for future GRS-IBS bridges.<figure id='attachment_8152' style='max-width:444px' class='caption aligncenter'><img class="size-full wp-image-8152" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of the GRS abutment with 90-degree angle. Source: Every Day Counts (EDC) GRS-IBS brochure." width="444" height="310" /><figcaption class='caption-text'> Figure 5. GRS abutment with 90-degree angle. Source: Every Day Counts (EDC) GRS-IBS brochure.</figcaption></figure>Conclusion: As the first bridge constructed using GRS-IBS technology, Bowman Road Bridge provides great insight into the performance of the technology. As of this writing, the bridge is 12 years old and still in very good condition. The bump normally formed in non-GRS-IBS bridges, due to uneven settlement between the superstructure and the substructure, is still not present within the Bowman Road Bridge; this has ensured users experience a smooth ride. Bowman Road Bridge has settled evenly due to the fact that, unlike with deep foundation supported bridges, the superstructure and substructure rest on the same soil. The integrated approach, created by constructing the reinforced soil layers between the approach embankments and the superstructure, also reduces differential settlement ensuring a smooth ride over the structure.In addition to constructing a well performing bridge, GRS-IBS technology allowed Defiance County to cut project costs by about 25 percent. These savings are estimated against single span bridges with traditional spill-through abutments and has made it possible for Defiance County to replace 34 deficient bridges using mostly local funds since 2005. As of 2017, Defiance County has the most GRS-IBS bridges in the country. Between 2005 and the time of this case history the average age of the bridges replaced by Defiance County was over 80 years. The newly constructed GRS-IBS bridges turned the average age of the Defiance County's bridge inventory to 35 years. GRS-IBS has allowed Defiance County to significantly reduce the average age of their inventory by replacing many of their older structures. By this measure, Defiance County has done a tremendous job improving its infrastructure.The lessons learned from the challenges encountered by Defiance County engineers were valuable and have contributed to the success of the GRS-IBS projects that followed in Defiance County and the rest of the country. The Defiance County engineers have continued to build GRS-IBS bridges and often share their knowledge through presentations at Every Day Counts (EDC) events, conferences, universities, ASCE chapters, and other professional societies. One of these presentations sparked interest in GRS-IBS among engineers in Hamilton County, Indiana and, since then, Hamilton County has successfully implemented their own GRS-IBS bridge improvement program.Project Contact: Warren Schlatter Defiance County Engineer Defiance County, OH <a href="mailto:dce@defiance-county.com">dce@defiance-county.com</a>(419) 782-4751Project Technical Paper: A technical paper has not been published for this project.REFERENCES“Geosynthetic Reinforced Soil (GRS) Integrated Bridge System (IBS) Technology”, (brochure, American Council of Engineering Companies of Massachusetts, 2016). GRS-IBS Brochure. Retrieved from: <a href="http://www.acecma.org/acecma/file/grs_ibs_brochure.pdf">http://www.acec…;. Accessed April 18, 2017.“Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) – Technology Overview”, (presentation, U.S. Department of Transportation, Federal Highway Administration). Retrieved from: <a href="https://www.ltap.org/resources/edc/downloads/EDCgrs-ibs.pdf">https://ww…;. Accessed April 19, 2017.Chris Kelsey, “NACE Report #3, April 19 – More GRS Experience Is Shared”, Geosynthetica, 2011. Retrieved from: <a href="http://www.geosynthetica.net/nace-report-3-april-19-more-grs-experience…;. Accessed April 19, 2017.Daniel Alzamora, phone conversation with the author of this document, May 16, 2017Warren Schlatter, phone conversation with the author of this document, June 6, 2017.Mike Adams, “The GRS bridges of Defiance County”, Geosynthetics, April/May 2008. Vol. 26. No. 2.Warren Schlatter, “Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) in Defiance, Ohio” (presentation, Ohio Department of Transportation, 2014). Retrieved from: <a href="https://www.dot.state.oh.us/Divisions/Planning/LocalPrograms/LTAP/Docum…;. Accessed April 19, 2017.Zheng, Y., Fox, P. J., and McCartney, J. S., “Numerical Study of the Compaction Effect on the Static Behavior of a Geosynthetic Reinforced Soil-Integrated Bridge System”, Geotechnical Frontiers, 2017, GSP 278.

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Technology

Mechanically Stabilized Earth Wall System