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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Approach Guardrail Transition Retrofit to Existing Buttresses &amp; Bridge Rails</title>
      <link>https://trid.trb.org/View/2433879</link>
      <description><![CDATA[The Nebraska Department of Transportation (NDOT) frequently applies roadway overlays to the surface of bridges to extend the bridge’s lifespan. To minimize repair costs, NDOT does not desire to replace or alter any bridge rails with adequate structural capacity and height. Bridge rails installed to National Cooperative Highway Research Program (NCHRP) Report 350 or Manual for Assessing Safety Hardware (MASH) standards are likely to remain in place, though their effective heights would be reduced by the overlay. This creates a problem of attaching new, 31-in. tall approach guardrail transitions (AGTs) to existing concrete bridge rails and buttresses (after an overlay) that were not designed for such connections and the resulting system may not be crashworthy to current safety standards. The objective of this project was to develop retrofit options for attachment of thrie-beam AGT systems to existing NDOT bridge railings and buttresses. The project began with a review of existing bridge railings and end buttresses used by NDOT to identify issues related to connection hardware alignment and crash safety performance. Retrofit options were then developed to address these issues while adhering to established design criteria. A new connector plate assembly was designed to facilitate the attachment of the thrie-beam terminal connector to these bridge railings and buttresses. Additionally, three retrofit concepts, including concrete fill, a steel assembly, and a curb, were considered to mitigate concerns related to vehicle snag below the thrie beam. These selected retrofit concepts were evaluated through a combination of structural analysis and computer simulated crash tests. All simulations of the AGT attached to these buttresses through these retrofit concepts met MASH Test Level 3 (TL-3) safety performance criteria.]]></description>
      <pubDate>Mon, 30 Sep 2024 17:21:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2433879</guid>
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    <item>
      <title>Centrifugal Model Test and Design Method for Temporary Retaining Wall Using Soil Buttress as Displacement Suppression</title>
      <link>https://trid.trb.org/View/2342138</link>
      <description><![CDATA[It is important to suppress the displacement of temporary retaining wall when excavating in urban areas close to existing structures. Soil buttresses have economic advantages compared to struts, such as in large-scale excavation works. On the other hand, a challenge in designing such temporary retaining walls is needed to consider displacement suppression mechanism using methods such as FEM. In this paper, the authors clarified the displacement suppression mechanism of soil buttresses using centrifuge model tests with excavation. Cutout shaped soil buttresses were proposed based on the test knowledge. In addition, the authors proposed a design method of temporary retaining walls using soil buttresses to suppress the displacement.]]></description>
      <pubDate>Fri, 12 Apr 2024 09:16:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/2342138</guid>
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    <item>
      <title>Study on force characteristics of catamaran buttress during floating</title>
      <link>https://trid.trb.org/View/1901261</link>
      <description><![CDATA[This paper puts forward a new method to measure the force characteristics of the buttress’ ship–pipe connection. First, the positions of stress sensors are determined by the numerical model, and the stress values at these positions are derived alongside a stress equation for the buttress. Then, the vertical stress values of the buttresses are obtained by using the established model; the results are in good agreement with the known external load. Considering the unevenness of the surface between the buttress and immersed tube, a horizontal stress equation for the whole buttress is put forward based on stress difference.Through analysis of data obtained from a real engineering project, it can be concluded that the vertical force on the buttresses fluctuates while the catamaran is floating, but within an acceptable range. The results can be used to guide future engineering projects.]]></description>
      <pubDate>Mon, 28 Feb 2022 09:53:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/1901261</guid>
    </item>
    <item>
      <title>Development of a Standardized Buttress for Approach Guardrail Transitions</title>
      <link>https://trid.trb.org/View/1763982</link>
      <description><![CDATA[Approach guardrail transitions (AGTs) incorporate increased post and rail sizes, reduced post spacings, specialized buttress end geometries, and other roadway features to smoothly transition from deformable W-beam guardrail to rigid barriers. This transition in barrier lateral stiffness requires specific combinations of these components to function properly. Changing components, or even the addition or removal of a curb below the rail, can negatively affect the safety performance of an otherwise crashworthy system. However, recent full-scale crash testing has indicated that a properly-designed buttress at the downstream end of an AGT may be utilized with multiple thrie-beam AGT systems. Thus, the objective of this project was to develop a standardized buttress to reduce vehicle snag and be compatible with a wide variety of previously-developed, 31-in. tall, thrie-beam AGT systems, either with or without a curb. The standardized buttress was designed with a dual taper on its front upstream edge. A shallower lower taper was designed to mitigate tire snag below the rail, while a steeper upper taper was designed to prevent vehicle snag and limit the unsupported span length of the guardrail. This buttress design was evaluated in combination with a critical AGT (i.e., an AGT with lower stiffness than other crashworthy AGTs) without a curb, representing a worst-case scenario. The standardized buttress was successfully crash tested to the 2016 Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3) safety criteria. Guidance was provided for both the attachment of the buttress to various crashworthy thrie-beam AGTs as well as how to transition the shape of the buttress to adjacent bridge rails or rigid parapets downstream from the AGT.]]></description>
      <pubDate>Thu, 21 Jan 2021 13:37:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/1763982</guid>
    </item>
    <item>
      <title>34-in. Tall Thrie Beam Transition to Concrete Buttress</title>
      <link>https://trid.trb.org/View/1706830</link>
      <description><![CDATA[Roadway resurfacing and overlay projects effectively reduce the height of roadside barriers placed adjacent to the roadway, which can negatively affect their crashworthiness. More recently, bridge rails and concrete barriers have been installed with slightly increased heights to account for future overlays. However, adjacent guardrails and approach transitions have not yet been modified to account for overlays. The objective of this project was to develop an increased-height, approach guardrail transition (AGT) to be crashworthy both before and after roadway overlays of up to 3 in. (76 mm). A 34-in. (864-mm) tall, thrie beam transition was designed such that the system would be at its nominal 31-in. (787-mm) height following a 3-in. (76-mm) roadway overlay. Additionally, the upstream end of the AGT incorporated a symmetric W-to-thrie transition segment, which would be replaced by an asymmetric transition segment after an overlay in order to keep the W-beam guardrail upstream from the transition at its nominal 31-in. (787-mm) height. The 34-in. (864-mm) tall AGT was connected to a modified version of the standardized buttress to mitigate the risk of vehicle snag below the rail. The barrier system was evaluated through two full-scale crash tests in accordance with Test Level 3 (TL-3) of the American Association of State Highway Transportation Officials’ (AASHTO) Manual for Assessing Safety Hardware (MASH). Both MASH test nos. 3-21 and 3-20 were conducted near the upstream end of the rigid buttress and satisfied all safety performance criteria. Thus, the 34-in. (864-mm) tall AGT with modified transition buttress was determined to be crashworthy to MASH TL-3 standards. Finally, implementation guidance was provided for the increased height AGT and its crashworthy variations.]]></description>
      <pubDate>Tue, 19 May 2020 16:39:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/1706830</guid>
    </item>
    <item>
      <title>Case History and Remediation of a Troublesome Rock Cut in Georgia, Vermont</title>
      <link>https://trid.trb.org/View/1692628</link>
      <description><![CDATA[In the early 1970’s shortly after construction, two significant rockfall events occurred at a rock cut located on I-89 NB at Mile Marker 107.50 in the Town of Georgia, Vermont. The rockfalls blocked both travel lanes of the northbound barrel of the Interstate. Smaller chronic rockfall events continued into the late 1990’s. In 2007, the rock cut was ranked within Vermont’s Rockfall Hazard Rating System as the 9th highest hazard rock cut. The rock cut was constructed within the Lower Cambrian Dunham Formation consisting of steeply dipping curved beds of dolomite forming the east limb of a syncline with its axis nearly parallel to the roadway. Remnant bedding dips moderately to steeply to the west with at least three major joint sets parallel to cleavage planes, forming planar and wedge failure features. Significant rockfall events have originated from these areas. In 2014, the rock cut was programmed for remediation. Due to the complex geology of the site, and poor blasting practices in the original construction, remediation options were utilized consisting of trim blasting, hand scaling, rock dowel and shear key installation, rock drains, and constructing shotcrete buttresses. The condition of the rock cut presented challenges during construction including trim blasting to address back-break from original construction, additional rock reinforcement to mitigate poorer than anticipated deteriorated rock conditions, and construction of a substantial shotcrete buttress to address a remaining overhanging rock mass.]]></description>
      <pubDate>Thu, 02 Apr 2020 09:43:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1692628</guid>
    </item>
    <item>
      <title>Development of a 34-in. Tall Thrie-Beam Guardrail Transition to Accommodate Future Roadway Overlays</title>
      <link>https://trid.trb.org/View/1577002</link>
      <description><![CDATA[Roadway resurfacing and overlay projects effectively reduce the height of roadside barriers placed adjacent to the roadway, which can negatively affect their crashworthiness. More recently, bridge rails and concrete barriers have been installed with slightly increased heights to account for future overlays. However, adjacent guardrails and approach transitions have not yet been modified to account for overlays. The objective of this project was to develop an increased-height approach guardrail transition (AGT) to be crashworthy both before and after roadway overlays of up to 3?in. The 34-in. tall, thrie-beam transition detailed here was designed such that the system would be at its nominal 31-in. height following a 3-in. roadway overlay. Additionally, the upstream end of the AGT incorporated a symmetric W-to-thrie transition segment that would be replaced by an asymmetric transition segment after an overlay to keep the W-beam guardrail upstream from the transition at its nominal 31-in. height. The 34-in. tall AGT was connected to a modified version of the standardized buttress to mitigate the risk of vehicle snag below the rail. The barrier system was evaluated through two full-scale crash tests in accordance with Test Level 3 (TL-3) of AASHTO’s Manual for Assessing Safety Hardware (MASH) and satisfied all safety performance criteria. Thus, the 34-in. tall AGT with modified transition buttress was determined to be crashworthy to MASH TL-3 standards. Finally, implementation guidance was provided for the 34-in. tall AGT and its crashworthy variations.]]></description>
      <pubDate>Fri, 01 Feb 2019 17:02:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1577002</guid>
    </item>
    <item>
      <title>Development of a Standardized Buttress for Approach Guardrail Transitions</title>
      <link>https://trid.trb.org/View/1493150</link>
      <description><![CDATA[Approach guardrail transitions (AGTs) incorporate increased post and rail sizes, reduced post spacings, and specialized buttress end geometries to smoothly transition from deformable W-beam guardrail to rigid barriers. This transition in barrier stiffness makes AGTs sensitive systems that require specific combinations of these components to function properly. Changing components, or even the removal of a curb below the rail, can negatively affect the safety performance of an otherwise crashworthy system. However, recent full-scale crash testing has indicated that a properly designed buttress at the downstream end of an AGT may be utilized with multiple AGT systems. Thus, the objective of this project was to develop a standardized buttress to reduce vehicle snag and be compatible with a wide variety of previously developed Thrie beam AGT systems, either with or without a curb. The standardized buttress was designed with a dual taper on its front upstream edge. A longer lower taper was designed to mitigate tire snag below the rail, while a shorter upper taper was designed to prevent vehicle snag and limit the unsupported span length of the rail. This buttress design was evaluated in combination with a critically weak AGT without a curb, which represented the worst-case scenario. The standardized buttress was successfully crash tested to MASH TL-3. Guidance was provided for both the attachment of the buttress to various Thrie beam AGTs as well as how to transition the shape of the buttress to adjacent bridge rails or rigid parapets downstream of the AGT.]]></description>
      <pubDate>Thu, 26 Apr 2018 14:04:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/1493150</guid>
    </item>
    <item>
      <title>Development of a Transition Between an Energy-Absorbing Concrete Barrier and a Rigid Buttress</title>
      <link>https://trid.trb.org/View/1482523</link>
      <description><![CDATA[From 2010 to 2015, MwRSF researchers developed the RESTORE barrier, which is a restorable MASH TL-4 median barrier with a steel and concrete rail supported by elastomer posts and steel skids. The research effort reported herein describes the initial development of a transition from the RESTORE barrier to a rigid TL-4 concrete buttress.  The previously-developed RESTORE barrier LS-DYNA model was validated against three full-scale vehicle crash tests. Several design concepts were generated through a series of brainstorming efforts. The primary transition concept consisted of a pin and loop connection between the RESTORE barrier and rigid concrete buttress, which was designed and evaluated with LS-DYNA computer simulation. Vehicle and system behavior were investigated using MASH test designation nos. 4-20, 4-21, and 4-22. Six horizontal gusset plates and drop-down pin allowed for limited deflection and rotation at the transition joint, but provided shear continuity between the two systems. A rounded-edge cover plate mitigated vehicle snag on the transition joint hardware. Eleven impact points were evaluated with each vehicle model to determine critical impact points for use in a future full-scale crash testing program. All occupant risk measures and vehicle stability were within MASH limits. Further design modifications are recommended to limit stresses in the transition joint hardware and to reduce excessive occupant compartment deformation that occurred when the small car impacted the concrete buttress end.]]></description>
      <pubDate>Mon, 25 Sep 2017 14:10:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/1482523</guid>
    </item>
    <item>
      <title>Geologic Causation and Mitigation Design for the US-89 Landslide Disaster, Bitter Springs, Arizona</title>
      <link>https://trid.trb.org/View/1472983</link>
      <description><![CDATA[Large ancient rock landslides or "megaslides" exist throughout much of the Grand Canyon area in Arizona. On February 20, 2013, a 500-foot-long section of pavement failed, closing US 89 in the Bitter Springs area. The Echo Cliffs of Northern Arizona consists of steep Triassic sedimentary rock that has been tectonically uplifted into a large monocline. Vertical relief of the cliffs is 1,500 feet. Slope failures along part of the Echo Cliffs are unique because they occur in the upper 1,000 feet and do not extend to the base of the cliffs. Geomorphic mapping and extensive subsurface exploration indicates that the cliffs initially went through a period of extensive debris slide failures (Pleistocene). Successive erosion and exposure of Chinle Formation claystone, along with the wet Pleistocene climate, resulted in the formation of large translational megaslides. Individual blocks are thousands of feet wide and range from 300- to 500-feet-thick. This translational failure is part of the toe of the ancient megaslide. Failure occurs along a relatively shallow dipping slip surface. Subsurface exploration indicates that, the re-activation of the landslide occurred under "dry" conditions. Re-activation of the landslide is considered to be due to long-term and episodic erosion at the base of the megaslide as well as long-term creep and plastic deformation of the Chinle Formation. To rebuild, a new road alignment shifted just east of the active slide, an extensive rock cut and subsequent massive rock buttress fill with an estimated volume of 1,000,000 yd.³ is proposed to stabilize the landslide.]]></description>
      <pubDate>Mon, 31 Jul 2017 16:36:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/1472983</guid>
    </item>
    <item>
      <title>Effectiveness of Buttress and Cross-Wall in Deep Excavations</title>
      <link>https://trid.trb.org/View/1417230</link>
      <description><![CDATA[Buttress and cross-wall have been widely adopted with success in soft ground excavation work. The interaction between the soil, buttress/cross-wall and diaphragm wall is a three dimensional (3D) problem but in practice the problem is commonly simplified into a two-dimensional problem. This study compared the contribution of buttress and cross-wall on the displacement of diaphragm wall via a series of 3D finite element (FE) analysis. The numerical procedure was first calibrated against the field data obtained from a 16 m deep excavation project in Taipei City. The model was then used in the subsequent parametric study to evaluate the efficiency of buttress and cross-wall for a diaphragm wall supported excavation. Result showed that cross-wall and buttress were equally efficient in restraining the lateral displacement of diaphragm wall.]]></description>
      <pubDate>Mon, 29 Aug 2016 11:14:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/1417230</guid>
    </item>
    <item>
      <title>An Innovative Case Study on the Use of Launched Nails for Landslide Repair</title>
      <link>https://trid.trb.org/View/1329679</link>
      <description><![CDATA[A record snowfall throughout the Rocky Mountains during the winter of 2010/2011 combined with torrential spring rainfall led to infrastructure damage throughout Montana, Wyoming, and North Dakota. Many roadways were closed due to flooding and landslides. Interstate 90 - between Hardin, MT and Buffalo, WY - experienced multiple deep-seated landslides and several shallow slips. One of the landslides occurred at MM 16.3 on the westbound on-ramp, a critical access point to I-90 due to the vicinity of the Wyoming Port of Entry. A 3-m to 4-m (10-ft to 12-ft) scarp near the guardrail led the Wyoming Department of Transportation (WYDOT) to look for innovative techniques to quickly stabilize the ramp to permit safe traffic flow. Safety and right-of-way concerns also complicated the design and construction of any earthwork structures. WYDOT chose launched (ballistic) soil nails faced with reinforced shotcrete to provide temporary stabilization of the near-vertical scarp. The temporary stabilization allowed for stability of the roadway platform and also permitted construction of a large earthen buttress. Due to the time and safety constraints involved, as well as the innovative technology selected, unique approaches in the slope stability modeling, onsite design, and construction planning were required.]]></description>
      <pubDate>Wed, 26 Nov 2014 15:07:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1329679</guid>
    </item>
    <item>
      <title>Geotechnical Challenges in Reclamation of a Soft Soil Site</title>
      <link>https://trid.trb.org/View/1302897</link>
      <description><![CDATA[This paper highlights the geotechnical challenges faced during reclamation of a soft soil site for an international container shipping terminal in Southern Vietnam. The terminal incorporates a pile-supported wharf with a barge quay and a 60-hectare (150-acre) upland development for container storage. This paper focuses on the settlement and slope stability challenges associated with reclamation of the upland portion of the terminal. Prior to development, the site comprised an intertidal salt marsh with ground surface elevation ranging from about -1 to +3.5 meters (-3.5 to +11.5 feet). Geotechnical exploration and testing indicated that the site was underlain by up to about 45 meters (150 feet) of very soft to stiff, highly compressible clay soils overlying medium dense to very dense sand deposits. In order to accommodate the design tidal range, development plans called for raising site grades to an average elevation of +6 meters (+19.5 feet). Settlement analysis indicated that consolidation settlement in excess of 3 meters (10 feet) could occur in the area of the container yard when site grades were raised and working loads applied. In order to reduce post-construction settlement, a preloading program using closely spaced prefabricated vertical drains was undertaken. Slope stability analysis indicated that placing fill over the weak clay soils would destabilize the waterside slope. Through a series of iterations of geotechnical design and collaboration between the civil/structural and geotechnical engineers, a buttressing system using a thickened section of blanket stone and armor stone was constructed to maintain the stability of the slope.]]></description>
      <pubDate>Mon, 05 May 2014 07:51:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/1302897</guid>
    </item>
    <item>
      <title>Liquefaction Mitigation on South Carolina Highway Bridge Projects</title>
      <link>https://trid.trb.org/View/1119356</link>
      <description><![CDATA[Until approximately the mid-1990s, the South Carolina Department of Transportation (SCDOT) seismic design was based on American Association of State Highway and Transportation Officials (ASHTO) Division 1A seismic specifications with a uniform hazard of 10% probability of exceedance in 50 years. In the mid to late 1990s, select projects were designed for an earthquake with a 2% probability of non-exceedance in 50 years and this design philosophy was incorporated into the SCDOT seismic design specifications in 2001. Many soil deposits in the South Carolina Coastal Plain are potentially liquefiable under the larger seismic hazard. As a result, various liquefaction mitigation measures have been incorporated into the final designs of SCDOT bridges and embankments. Mitigation methods have included vibro-replacement stone columns, vibro-concrete columns, geocomposite drains, and stabilizing buttresses. A comprehensive summary of SCDOT projects that have included some form of liquefaction mitigation is presented in this paper. Additional details on the subsurface conditions and design objectives are provided for selected case histories.]]></description>
      <pubDate>Tue, 25 Oct 2011 11:46:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/1119356</guid>
    </item>
    <item>
      <title>120-Inch Olmsted and 90-Inch Alpine Aqueducts Landslide Crossings</title>
      <link>https://trid.trb.org/View/759537</link>
      <description><![CDATA[The Olmsted Flowline is a vital link in delivering the Central Utah Water Conservancy District's municipal and industrial water.  In the last 20 years, three active landslides have interrupted the service of the Flowline and one of its branches, the Alpine Aqueduct (AA-1).  For each landslide crossing, the District has determined the causes, identified solutions, engineered remedies, and constructed replacement facilities to improve the reliability of these aqueducts.  The causes of the three landslides were similar--weak geologic formations and groundwater--but their movement rates varied from under 3 mm (1/8 in.) per year to over 6.1 m (20 ft) per day.  Accordingly, design approaches for circumventing or crossing the landslides varied with their movement rates.  Constructed facilities included a tunnel (horizontal and vertical realignment in bedrock), two above-ground pipes, surface and groundwater removal, slope buttressing, and soil nailing.  This paper presents how the reliability and maintenance problems of multiple active and inactive landslides under two major aqueducts were addressed through the design and construction of various types of replacement conduits and slope stabilization facilities.]]></description>
      <pubDate>Tue, 23 Aug 2005 15:39:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/759537</guid>
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