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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <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>Delineation of Linear Roadside Hardware Systems and Roadside Obstacles</title>
      <link>https://trid.trb.org/View/2682135</link>
      <description><![CDATA[This report provides information on the practices for delineating linear roadside hardware systems and roadside obstacles, including their descriptions, effectiveness, and appropriate applications. This information was developed from (1) a review and evaluation of current practices relevant to the delineation of linear roadside hardware systems and roadside obstacles, (2) an analysis of crash data and the effectiveness of delineation practices in reducing crash severity or crash frequency, and (3) a human factors study evaluating the effectiveness of several roadside hardware and roadside obstacle delineation practices. The information contained in this report will help highway agencies and other organizations concerned with safety aspects on highways make informed decisions regarding the delineation of roadside hardware and obstacles to reduce crashes and improve safety.]]></description>
      <pubDate>Sun, 22 Mar 2026 17:18:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2682135</guid>
    </item>
    <item>
      <title>Audible Warning System on TMA and Maintenance Trucks</title>
      <link>https://trid.trb.org/View/2675924</link>
      <description><![CDATA[The project aims to increase the safety of truck-mounted attenuators by developing a system that uses automated audible and visual warnings to detect potential collisions and notify drivers. Researchers will optimize the design of audible warning devices based on physical, engineering and human factors to increase performance in complex operating environments. The research will help the Illinois Department of Transportation build and test prototypes in real-world conditions, especially around work zones, helping to reduce collisions, damage to equipment and traffic disruptions.]]></description>
      <pubDate>Mon, 02 Mar 2026 11:25:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2675924</guid>
    </item>
    <item>
      <title>Autonomous Truck-Mounted Attenuator Prioritization Study for Work Zones</title>
      <link>https://trid.trb.org/View/2672764</link>
      <description><![CDATA[Work zone safety is a critical concern for Utah Department of Transportation (UDOT) and other transportation agencies due to the high incidence of crashes involving roadside operations. One of the most vulnerable roles in these settings is the Truck Mounted Attenuator (TMA) driver. TMAs are designed to protect road crews by absorbing the impact of errant vehicles, but the presence of a driver in these vehicles inherently places them at significant risk. Despite efforts to improve work zone safety, rear-end collisions involving TMAs continue to result in severe injuries and fatalities nationwide. This ongoing issue underscores a significant gap in safety that persists despite advancements in signage, barriers, and traffic control strategies. To address this issue, Autonomous Truck Mounted Attenuator (ATMA) technology has been developed with the objective of removing the driver from the TMA vehicle. This technology aims to reduce risk exposure for workers by allowing the impact vehicle to operate without an onboard driver during mobile operations such as striping, sweeping, and debris collection. By removing the driver from the most dangerous vehicle in the work zone -- the impact truck -- agencies can significantly mitigate the risk of fatal injuries resulting from rear-end collisions. Several state DOTs, including Florida, Indiana, Tennessee, and California, have piloted this technology, providing valuable insights into both its potential and limitations. Their findings indicate a range of operational, legal, and technical challenges that must be addressed prior to broad deployment. Common operational issues include system reliability in global positioning system (GPS)-compromised areas, limited obstacle detection in constrained environments, communication delays in remote or urban canyon settings, and more complex tasks requiring stop-and-go movements or precise maneuvers in tight spaces. Given Utah's diverse roadway environments, ranging from dense urban corridors to expansive rural highways, this research is expected to address multiple interrelated challenges on the adoption of ATMA technology: whether current Utah laws permit autonomous commercial vehicle operations such as ATMAs and what updates would be needed for eventual implementation, how well the technology performs under Utah's operational and environmental conditions, and whether the economic investment is justified given both the anticipated safety benefits and the operational constraints. Factors such as weather-related impacts (snow, ice, dust), varying road geometries, and a wide range of traffic volumes further complicate direct adoption without local validation.]]></description>
      <pubDate>Sun, 22 Feb 2026 10:29:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/2672764</guid>
    </item>
    <item>
      <title>Highway Workers’ Perception of Autonomous Truck-Mounted Attenuator: A Case Study in Indiana’s DOT</title>
      <link>https://trid.trb.org/View/2562231</link>
      <description><![CDATA[Highway maintenance operations have been associated with high rates of crashes, leading to workers’ injuries and fatalities. To protect the state Department of Transportation (DOT)’s maintenance workers, autonomous systems have been implemented in various work zone maintenance operations, including the Autonomous Truck-Mounted Attenuator (ATMA). Though the ATMA has been tested in several DOTs, DOT workers’ perception of the ATMA has not been well studied. To understand workers’ perception of the ATMA system, this study collected evaluations from 14 Indiana DOT workers after 6 weeks of closed-road and open-road tests. The test was conducted during four mobile work zone operations and under different roadway conditions. The findings of this study suggest that workers believe the ATMA system improves their safety and productivity in these operations. Additionally, longer exposure to ATMA operations leads to more positive evaluations. Although previous studies suggest that age is a key factor that influences users’ evaluations of emerging technologies, this study does not reveal any age-related differences. The findings of this study provide insights into future autonomous system implementation and suggest that proper training is an indispensable step for the adoption of such technologies.]]></description>
      <pubDate>Fri, 20 Feb 2026 15:28:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2562231</guid>
    </item>
    <item>
      <title>Vortex-induced vibration of box girders with non-uniformly arranged crash barriers</title>
      <link>https://trid.trb.org/View/2632207</link>
      <description><![CDATA[This study investigates the aerodynamic influence of Non-Uniformly Arranged Crash Barriers (NUACB) on box girder vortex-induced vibration (VIV) through large-scale sectional model wind tunnel tests. The analysis covers spectral characteristics, velocity field and spanwise evolution, as well as spatial distributions of turbulence intensity and streamwise turbulence integral length scale. The results show that the girder exhibits pronounced vertical bending VIV at 3° and 5° angles of attack (AoAs). Its drivers include spectral energy concentration near the lock-in frequency in leeward and wake regions; accelerated windward shear-layer growth with associated leeward flow separation; elevated overall turbulence intensity; and formation of spanwise-coherent vortical structures on the top surface and in the wake. NUACB effectively suppresses VIV by attenuating resonance-frequency spectral peaks, inhibiting shear-layer maturation, stabilizing leeward flow attachment, and promoting wake recovery. It also significantly reduces turbulence intensity and streamwise integral length scales in critical zones, thereby disrupting spanwise coherence of vortex shedding. Although localized vortices persist near blocked segment edges, sustained spanwise synchronization is eliminated. Based on these findings, we propose the Turbulence-Regulated Vibration Suppression Theory (TRVST). TRVST holds that targeted aerodynamic interventions can reconfigure bluff-body turbulence, disrupt shear-layer evolution, and preclude spanwise vortex formation from inception. This approach is validated by combined turbulence-based metrics and offers a new framework for aerodynamic VIV suppression in bridge engineering.]]></description>
      <pubDate>Thu, 22 Jan 2026 09:24:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2632207</guid>
    </item>
    <item>
      <title>Automating the Lateral Strength Assessment of the American Association of State Highway and Transportation Officials (AASHTO) Standard and Substandard Concrete Barriers</title>
      <link>https://trid.trb.org/View/2655577</link>
      <description><![CDATA[One of the important outcomes of the KTRAN: KSU-21-6 project that concluded in May 2023 is the development of a closed form procedure to assess the ultimate lateral strength of sub-standard concrete barriers using a rigorous yield line analysis beyond the prediction capabilities of the current American Association of State Highway and Transportation Officials (AASHTO) procedure. This method was confirmed by a truss analogy approach and finite element analysis. The closed form equations developed in that project were tedious to carry out by hand or Excel and the establishment of a computer software is deemed to be the most efficient and useful tool to add to the Kansas Department of Transportation (KsDOT)’s assessment capabilities. The findings of the earlier study revealed the fact that the lateral ultimate strength of sub-standard barriers exceed the current strength classification of AASHTO standard barriers leaving the geometrical height of the sub-standard barrier as the only deficiency to overcome in order to make such barriers as good as the standard barriers in mitigating truck crashes. Accordingly, the PI’s are proposing to develop a software package that implements a rigorous yield line analysis procedure incorporating the material-specific properties (steel and concrete) in determining the lateral ultimate strength of barriers. The software will be equally applicable to standard and sub-standard barrier assessments. It is expected to yield a powerful tool that can optimize the strength design of any concrete barrier. This is expected to lead to improvements in both the geometry, concrete and reinforcement properties in realizing an optimum target design. It will also allow examining various types of barrier designs to make the best educated engineering decisions on implementing one type over the other as well as coming up with new designs. 

The specific three main research tasks include: 1) Developing the lateral ultimate strength assessment software for standard and sub-standard barriers; 2) Generalizing the input parameters to explore new barrier geometries; 3) Writing and submitting the final project report and the developed comprehensive software.]]></description>
      <pubDate>Thu, 15 Jan 2026 12:25:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/2655577</guid>
    </item>
    <item>
      <title>Development of a Crash Cushion Utilising Waste Tires as an Impact Absorber</title>
      <link>https://trid.trb.org/View/2633348</link>
      <description><![CDATA[This paper presents the development of a crash cushion or crash attenuator utilising recycled automobile tires as an energy absorber. The study investigates the characteristics of waste tire stiffness, focusing on the effects of tire size and tire quantity. A mathematical model is proposed using numerical integration, implemented in MATLAB/Simulink to simulate the crash cushion’s behaviour under impact conditions. To validate the accuracy of mathematical model, comprehensive experimental crash tests are conducted. The results obtained from acceleration-time and deformation-time responses are meticulously compared between the experimental and simulated responses. The good agreement confirms the mathematical model’s accuracy and reliability in predicting crash cushion performance. Additionally, a parametric study is undertaken using the validated model, exploring the influence of impact speed, tire quantity, and tire stiffness on the crash cushion’s overall performance. The findings in this study offer valuable guidance for the design and optimisation of crash attenuators using recycled automobile tires. Ultimately, this research contributes to advancing sustainable and cost-effective road safety solutions by harnessing recycled materials for crash mitigation purposes. It underscores the potential of waste tires as effective energy absorbers in enhancing road safety infrastructure.]]></description>
      <pubDate>Tue, 13 Jan 2026 09:20:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2633348</guid>
    </item>
    <item>
      <title>A novel GFRP lattice-foam sandwich anti-collision island: Design, experimental, numerical investigation and application</title>
      <link>https://trid.trb.org/View/2619286</link>
      <description><![CDATA[Conventional concrete anti-collision islands are prone to structural damage due to their high stiffness and limited energy absorption capacity, which increases the risk of personal injury during vehicle impacts. To address these shortcomings, this study proposes a novel flexible anti-collision island composed of a Glass Fiber Reinforced Polymer (GFRP) lattice–foam sandwich structure, inspired by the successful application of lattice–foam systems in bridge pier protection, where their lightweight and deformable features have been proven effective in dissipating impact energy. Drop-weight impact tests were first conducted to characterize the mechanical response of typical curved sandwich components under impact loading. Thereafter, a finite element model was developed to further assess the peak impact force and deformation of the proposed anti-collision island under real-life vehicle collision scenarios. The results indicate that the curved sandwich component significantly reduced the depth of damage to the concrete structure and effectively preserved overall structural integrity. Compared to traditional rigid concrete designs, the new flexible anti-collision island reduced peak impact forces by up to 57.6 %. It also effectively mitigated the “climbing effect” of vehicles. The proposed structure has already been implemented in real-world projects, demonstrating its reliable reproducibility and potential for broader application in constructing flexible impact-resistant infrastructures.]]></description>
      <pubDate>Wed, 31 Dec 2025 10:56:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2619286</guid>
    </item>
    <item>
      <title>From Experimental Investigation to Optimized Design: A Time-Efficient Methodology for Carbon Fiber Composite Crash Structures in Formula Student Applications</title>
      <link>https://trid.trb.org/View/2610747</link>
      <description><![CDATA[This study presents the design and numerical validation of a composite impact attenuator, with Formula Student serving as a proof of concept. The research methodology involved an initial calibration phase, where simulations of simple test geometries were iteratively refined to match experimental data from dynamic tests within a 1% error margin. These validated material parameters were then applied to a final impact attenuator design featuring a five-tube configuration. To enhance time and cost efficiency, physical testing was conducted only at the intermediate component level, where simulation models were calibrated. The final crash structure was then optimized entirely through virtual simulations, eliminating the need for full-scale physical prototyping. Finite element simulations demonstrated that the proposed structure meets established deceleration and energy dissipation criteria with a significant safety margin. Additionally, compared to a commercially available aluminum honeycomb attenuator, the composite design achieved equivalent energy absorption characteristics while reducing weight by 13%. These findings validate the proposed methodology and highlight the advantages of composite crash structures for high-performance applications.]]></description>
      <pubDate>Mon, 15 Dec 2025 10:32:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/2610747</guid>
    </item>
    <item>
      <title>ATMA for Work Zone Safety: Data Management Plan</title>
      <link>https://trid.trb.org/View/2625420</link>
      <description><![CDATA[The Autonomous TMA (ATMA) for Work Zones project features a multi-state application, led by the Colorado Department of Transportation (CDOT), Minnesota Department of Transportation (MnDOT), Oklahoma Department of Transportation, Wisconsin Department of Transportation (WisDOT), and academia partners: Pennsylvania State University (PennState), University of California-Davis (UCD), University of Oklahoma, and University of Wisconsin. This project aims to build internal buy-in and partnerships at a national level, evaluate and integrate the technology under a diverse set of operational design domains and environments, and carry out the needed planning to identify and address current barriers that have prevented State DOTs from deploying the innovative technology at scale. These planning efforts are essential to support the Stage 2 implementation that will feature a variety of deployment of ATMA at each state, to significantly expand deployment of autonomous maintenance technology to operational design domains, environments, and scenarios that are critical for safety in work zones and also demonstrate proof of a DOT capability to integrate the innovation in their operations.]]></description>
      <pubDate>Thu, 11 Dec 2025 09:44:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/2625420</guid>
    </item>
    <item>
      <title>ATMA for Work Zone Safety [supporting dataset]</title>
      <link>https://trid.trb.org/View/2625419</link>
      <description><![CDATA[We collected and archived operational log messages from Autonomous TMA (ATMA) systems deployed in Colorado, Wisconsin, Minnesota, and Oklahoma. The log files are automatically generated by each ATMA’s onboard control computer and record detailed information on system behavior, vehicle dynamics, and navigation status during deployment. The dataset totals approximately 1.4 GB and includes around 3,800 CSV files organized by state and date of collection.]]></description>
      <pubDate>Thu, 11 Dec 2025 09:44:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/2625419</guid>
    </item>
    <item>
      <title>Development of Autonomous Truck Mounted Attenuator (ATMA) Deployment Guidelines Considering Traffic and Safety Impacts</title>
      <link>https://trid.trb.org/View/2636014</link>
      <description><![CDATA[The Autonomous Truck Mounted Attenuator (ATMA) system represents a specialized application of connected and autonomous vehicle (CAV) technologies, designed to enhance worker safety during roadway maintenance operations. Despite its growing adoption across state agencies, formalized deployment criteria remain absent from national guidelines such as the MUTCD, prompting individual DOTs to define their own standards. This study addresses a critical deployment challenge: identifying the appropriate traffic conditions—i.e., the Operational Design Domain (ODD)—under which ATMA can be safely and effectively used. The research begins by analytically modeling the reduced discharge rate resulting from ATMA-induced moving bottlenecks on multilane highways. Using this as a foundation, microscopic traffic simulation is applied to assess the resulting impacts on vehicle delay and traffic density—key metrics for determining Level of Service (LOS) as per the Highway Capacity Manual (HCM). Through this modeling framework, a functional relationship is established between Average Annual Daily Traffic (AADT) and LOS. The approach is validated using high-resolution NGSIM trajectory data, which confirms the model’s ability to accurately reflect capacity reductions caused by slow-moving ATMA vehicles. Sensitivity analyses further reveal that roadway performance is highly influenced by K and D factors, as well as ATMA travel speed. Results suggest that, to maintain LOS at grade C, an AADT threshold of approximately 40,000 vehicles per day provides a practical design guideline.]]></description>
      <pubDate>Tue, 09 Dec 2025 09:18:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/2636014</guid>
    </item>
    <item>
      <title>Fracture behavior and enhancement of crash cushion with bolted reinforced honeycomb under large deformation</title>
      <link>https://trid.trb.org/View/2569346</link>
      <description><![CDATA[This study uncovers an often-overlooked fracture mechanism in single shear bolted honeycomb structures under large deformations and proposes a double shear bolted reinforcement to resolve it. Quasi static compression tests on subdomain and full-scale specimens reveal that single shear connections concentrate stresses around bolt holes, promoting localized fractures that derail the intended negative Poisson’s ratio (auxetic) transition and weaken energy absorption. By contrast, the newly introduced double shear bolted configuration uniformly redistributes loads, postpones crack initiation, and preserves stable auxetic deformation. A further derivation further clarifies how cell rotation leads to a negative Poisson’s ratio, markedly boosting the specific energy absorption. Finally, a real car crash test validates that this enhanced reinforced honeycomb maintains structural integrity and efficient energy dissipation under extreme impact loading, thus ensuring controlled large deformation. These findings demonstrations that double shear bolting not only mitigates fractures but also leverages the negative Poisson’s ratio effect in honeycomb crash cushions. The resulting structure offers a lightweight, cost effective, and robust solution for highway safety applications, marking a significant advance in vehicular collision protection.]]></description>
      <pubDate>Mon, 15 Sep 2025 10:34:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/2569346</guid>
    </item>
    <item>
      <title>MASH Allowable Flare Rates for Portable Single-Slope Concrete Barriers</title>
      <link>https://trid.trb.org/View/2589146</link>
      <description><![CDATA[Portable concrete barriers (PCBs) are commonly used to provide positive protection in work zones. They also shield work-zone personnel from errant motorists when activities are being performed near the edge of the roadway. The exposed ends of PCBs can pose a hazard to motorists if left untreated. A common practice is to install a suitable crash attenuator at the end of the barrier to mitigate this hazard. However, this solution can be costly and time-consuming. When space permits, an alternative is to flare the PCB away from traffic to a point where the exposed end is outside the clear zone for adjacent traffic. Currently, limited guidance exists on the acceptable flare rate for PCBs under the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) 2016 guidelines. This paper evaluates the flare rate of the Texas Department of Transportation’s (DOT) freestanding 42-in. single-slope PCB through finite element (FE) analysis and crash testing according to the safety-performance criteria included in MASH. The flared single-slope PCB met the performance criteria for MASH Test Level 3 (TL-3) longitudinal barriers according to the implementation guidance provided.]]></description>
      <pubDate>Thu, 21 Aug 2025 09:19:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2589146</guid>
    </item>
    <item>
      <title>Developing an Enhanced Protection of Median Openings Between Parallel Bridge Structures</title>
      <link>https://trid.trb.org/View/2589092</link>
      <description><![CDATA[The objective of this project was to develop a method to prevent errant motorists from entering the median openings between parallel bridge structures. This project identified characteristics that could be used to target potential sites for implementation of a median opening protection system (MOPS). In this identification process, the research team completed a systematic approach analysis on the available crash data to determine these characteristics. Because of the risk associated with larger vehicles being involved with this type of crash, the research team was tasked with investigating both the crashes involving median opening areas and the crashes involving buses. Additionally, this project investigated readily available technologies for their application in a vehicle arresting system. This system would be implemented in median openings between parallel bridge structures and would arrest errant vehicles before they plunged into the hazard below the bridge. Last, the research team developed a MOPS using readily available technologies and evaluated the MOPS through full-scale crash testing.]]></description>
      <pubDate>Wed, 20 Aug 2025 11:56:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2589092</guid>
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