Mount Pleasant Road Bridge Pennsylvania

<figure id='attachment_8154' style='max-width:1334px' class='caption aligncenter'><img class="size-full wp-image-8154" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of the Completed Mount Pleasant Road Bridge." width="1334" height="1000" /><figcaption class='caption-text'> Figure 1. Completed Mount Pleasant Road Bridge. Source: PennDOT.</figcaption></figure>Location: Huston Township, Clearfield County, Pennsylvania Owner: Huston Township Year Constructed: 2011 National Bridge Inventory (NBI) Number: n/a Crossing Type: Roadway bridge over stream Superstructure Type: Timber Span: 18 feet Maximum Wall Height: 6.4 feet Maximum Wall Face Width (edge to edge): 30 feet Skew: 0 degrees Facing Type: Concrete Masonry Unit (CMU) Average Daily Traffic (ADT) (when constructed): 400 (less than) Contract Type: Design-Build (In-house) Unique Project Feature: The first GRS-IBS bridge in Pennsylvania; built by county work forceBackground: In July 2011, Huston Township in Clearfield County, Pennsylvania had to close the Mount Pleasant Road (T-522) Bridge because it was in deteriorating condition and posed a safety risk to crossing vehicles (see figure 3). The old bridge span was about 20 feet and had a low average daily traffic (ADT) of less than 400. The deficient bridge was located along a school bus route and it was imperative the new structure be constructed rapidly to minimize disruption to school bus service. An alternative school bus route was available, but it involved a steep road that was dangerous during colder months and the school district decided not to use the route after the end of October. The decision to forgo use of the alternative route inconvenienced families residing on the other side of the bridge, and families had to drop their children off at a certain location to be picked up by the bus. In addition to its location along a school bus route, the Mount Pleasant Road Bridge crossed a stream that supported spawning trout. As result, construction of a replacement bridge would not be allowed after October 1, when the trout spawning season began. While the Pennsylvania Fish Commission eventually extended this deadline to October 15, the timeframe still posed a challenge.<figure id='attachment_8155' style='max-width:1028px' class='caption aligncenter'><img class="size-full wp-image-8155" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Sketches of the project location. To the left, location of Clearfield County, Pennsylvania, to the right, location of Mount Pleasant Road Bridge." width="1028" height="496" /><figcaption class='caption-text'> Figure 2. (a) Location of Clearfield County, Pennsylvania and (b) Mount Pleasant Road Bridge. Source: Open Street Map, ESRI, FHWA.</figcaption></figure>To complete the replacement of the Mount Pleasant Road Bridge on time and in a cost-effective manner, Huston Township consulted the local Municipal Services Unit of Pennsylvania Department of Transportation (PennDOT). The Municipal Services Unit suggested using Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS), an innovative bridge replacement method to construct the bridge quickly and at low cost. GRS-IBS also boasted a relatively simple construction process that could be handled by the equipment and construction crews already possessed by Huston Township. After careful consideration, the township decided to use GRS-IBS to replace the Mount Pleasant Road Bridge. The project was the first GRS-IBS bridge in Pennsylvania and, as PennDOT had not yet developed GRS-IBS guidance documents, design of the project relied on plans and standards developed by Federal Highway Administration (FHWA).Deployment: The Mount Pleasant Road Bridge was constructed using local municipal equipment and construction crews, which reduced the cost of the project. Local contractors were hired to perform the excavation work and carry out guard rail installation.<figure id='attachment_8156' style='max-width:556px' class='caption aligncenter'><img class="size-full wp-image-8156" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of the old Bridge with deteriorating abutments." width="556" height="363" /><figcaption class='caption-text'> Figure 3. Old Bridge with deteriorating abutments. Source: PennDOT.</figcaption></figure>Construction on Mount Pleasant Road Bridge began on October 6, 2011. To minimize disturbance of the trout, GRS abutments and any needed construction around the stream were completed by October 15th. Concrete Masonry Unit (CMU) blocks were used to construct the facing of a six-foot tall wall. Upon completion of the GRS abutments, the prefabricated timber superstructure, spanning 18 feet, was delivered from a fabricator in Ohio and installed (see figure 4). Total construction time, from the beginning of excavation to the opening of the bridge to traffic, was 35 days. The total cost of the project was $102,000 and estimated project savings were at least 50 percent when compared to similar bridges in neighboring municipalities.<figure id='attachment_8157' style='max-width:560px' class='caption aligncenter'><img class="size-full wp-image-8157" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of the installation of prefabricated timber superstructure." width="560" height="345" /><figcaption class='caption-text'> Figure 4. Installation of prefabricated timber superstructure. Source: PennDOT.</figcaption></figure>The Mount Pleasant Road Bridge project generated a lot of interest among other municipalities in Pennsylvania, and many of these municipalities went on to deploy GRS-IBS technology with the help of PennDOT. As of this writing, 25 GRS-IBS bridges have been successfully completed in Pennsylvania. The GRS-IBS bridges constructed between 2011 and 2016 are presented in figure 5. Figure 5 demonstrates that the GRS-IBS technology has been deployed across almost all of the state’s districts. To help municipalities, PennDOT developed straightforward design guidance documents (e.g., MS-0460-0010 of Publication 447 and standard plans BD-697M) for GRS-IBS that were instrumental in Pennsylvania’s success deploying the technology.<figure id='attachment_8158' style='max-width:1450px' class='caption aligncenter'><img class="size-full wp-image-8158" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Sketch showing the distribution of GRS-IBS bridges across Pennsylvania. Numbers in red represent state’s districts." width="1450" height="753" /><figcaption class='caption-text'> Figure 5. Distribution of GRS-IBS bridges across Pennsylvania. Numbers in red represent state’s districts. Source: PennDOT.</figcaption></figure>Project Challenges and Solutions: The general challenges and solutions described below are related to the Mount Pleasant Road Bridge and other early GRS-IBS projects completed in Pennsylvania. Municipalities in Pennsylvania and at PennDOT learned from these challenges and have applied this knowledge to future GRS-IBS projects.Attention to detail during construction Attention to detail is critical when it comes to GRS-IBS construction. This is especially true for Reinforced Soil Foundation (RSF) construction. One of the major challenges in constructing the RSF, a granular fill material that is compacted and encapsulated with a geotextile, is maintaining a leveled surface. Since an unleveled surface can create difficulties in constructing a straight facing wall, it is integral that the RSF be leveled prior to placement of the first layer of geosynthetic reinforced soil; this should be done through close communication with construction crews and by constantly checking the RSF surface.Lack of CMU blocks meeting FHWA recommended material properties Current GRS-IBS guidance documents developed by PennDOT recommend the use of CMU blocks. However, CMU blocks that meet GRS-IBS specifications can be difficult to source in Pennsylvania. As a solution, the GRS-IBS design guidelines allow for the use of other blocks upon approval from PennDOT. The flexibility to use other blocks along with the procurement of CMU blocks that meet the material properties recommended by FHWA from other states has been helpful in constructing GRS-IBS bridges in Pennsylvania. The facing is not a structural component and just needs to stand up to the environment over time. The important aspect of the facing is to make sure the material can last and will meet the owner's aesthetic requirements.Promoting GRS-IBS technology GRS-IBS technology has to be promoted to ensure interested parties are aware of its advantages. As with any new technology, some feel that there are risks to implementing GRS-IBS. To spread the word about the benefits of GRS-IBS, significant efforts have been made to promote GRS-IBS technology in Pennsylvania. These efforts involved numerous presentations, training sessions, and publications. Since 2011, PennDOT has collaborated with FHWA to present at various districts in Pennsylvania, webinars, Every Day Counts (EDC) summits, the Transportation Research Board, the International Bridge Conference, and other organizations or events. The Pennsylvania GRS-IBS bridges have been featured in many magazines and newsletters. Additionally, PennDOT has been collecting and analyzing its GRS-IBS bridge costs and comparing them to conventional bridge projects of similar geometry and site conditions. The results of these cost comparisons revealed that GRS-IBS generates an average savings of 50 percent. These efforts have greatly contributed to the spread of GRS-IBS technology within the state and nationwide. Sharing GRS-IBS knowledge through presentations and publications has created a conversation between proponents of the technology and those that have reservations about GRS-IBS; this communication has enriched the discussion around GRS-IBS technology and both parties have been able to learn from each other.Conclusion: The replacement of Mount Pleasant Road Bridge proved that GRS-IBS can be an economical solution for municipalities in Pennsylvania. Since completion of the Mount Pleasant Road Bridge, GRS-IBS has become a part of the “toolkit” for replacement of low-ADT local roads in the state. Success with low-ADT bridges led PennDOT to start developing design guidance documents for GRS-IBS bridges serving higher ADT roads with more frequent truck traffic. This work involves collection of information on existing GRS-IBS bridges serving high-ADT roads (e.g. Echo Bridges in Echo, Utah) and identifying similar candidates in Pennsylvania. This progression in the use of GRS-IBS technology is a testament to PennDOT’s confidence in GRS-IBS technology and will result in more bridges built using this method.Project Contact: Randy Albert, P.E. Municipal Services Supervisor Pennsylvania Department of Transportation galbert@pa.gov (814) 765-0408Project Technical Paper: A technical paper has not been published for this project.REFERENCES“Bridge to Success: Bridge replacement technology saves township time and money”, Moving Forward: A quarterly Review of news and information about Pennsylvania local roads”, PennDOT Local Technical Assistance Program. Retrieved from: <a href="http://www.dot.state.pa.us/public/pdf/BPR_PDF_FILES/Documents/LTAP/Fina…;. Accessed June 21, 2017.“GRS-IBS Implementation Review” (presentation, Pennsylvania Department of Transportation, September 15, 2015).Adams, M. and Nicks, J. E., “Design and Construction Guidelines for Geosynthetic Reinforced Soil Abutments and Integrated Bridge Systems DRAFT”, Federal Highway Administration, McLean, VA, 2017.Commonwealth of Pennsylvania Department of Transportation, “Publication 447 - Approved Products for Lower Volume Local Roads, MS-0460-0011” (design guidance document, Pennsylvania Department of Transportation).Commonwealth of Pennsylvania Department of Transportation, “Standard Geosynthetic Reinforced Soil Integrated Bridge System Plans – BD-697M” (standard plans, Pennsylvania Department of Transportation, 2014).Daniel Alzamora, phone conversation with the author of this document, May 16, 2017Randy Albert, “PennDOT GRS-IBS Perspective” (presentation, Pennsylvania Department of Transportation, 2015).Randy Albert, phone conversation with the author of this document, June 20, 2017.

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Technology

Mechanically Stabilized Earth Wall System