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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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      <title>The Effect of In-Stream Construction Activities on Turbidity, Suspended Sediment, and Sediment Loads</title>
      <link>https://trid.trb.org/View/2703847</link>
      <description><![CDATA[Transportation construction activities involving in-stream work can mobilize sediment and elevate turbidity, which can affect sensitive aquatic species such as freshwater mussels. Although cofferdams are used to isolate construction areas and limit sediment mobilization, their installation and removal create some degree of sediment release as a result of unavoidable streambed disruptions. To support more informed impact assessments and survey requirements for aquatic species protection, this study determined the transport distances of sediment associated with the installation and removal of cofferdams. Related objectives were to compare the effect of cofferdam-related construction events on sediment loads and to document the factors that affect recovery times and sediment loads. Streams associated with two bridge replacement projects in Virginia involving different but commonly used cofferdam types (sheet pile and sandbag or Jersey barrier) were instrumented with 19 turbidity sensors positioned upstream and up to 2,600 feet downstream of construction. In addition to continuous turbidity monitoring, data collection included water sampling and field measurements used to determine suspended sediment concentration and site-specific rating curve development. Suspended sediment loads were calculated using stream discharge, suspended sediment concentration, and duration of cofferdam-related construction events. Across both sites, peak turbidity increases occurred immediately downstream of the cofferdam, with values as high as 238 Formazin Nephelometric Units at Site 1 and 3,324 Formazin Nephelometric Units at Site 2, which returned to background levels within 50 to 100 feet downstream. Sediment loads attributable to construction ranged from 3 to 636 pounds, and for most cofferdam-related construction events, more than 75% of the sediment load occurred in the first 50 feet downstream. The use of sandbag or Jersey barrier cofferdams generated higher turbidity and sediment loads than sheet piles, largely because installation and removal required more streambed disturbance. For all cofferdam-related construction events, turbidity levels returned to background levels between 5 and 90 minutes. Sediment load calculations from evaluated precipitation events were one to three orders of magnitude higher than loads from cofferdam-related construction events. The findings can help inform assessments of potential mussel impacts from in-stream projects involving cofferdams conducted under comparable conditions. It is recommended that the Virginia Department of Transportation’s Environmental Division share this report with the Virginia Field Office of the U.S. Fish and Wildlife Service and aquatic program staff of the Virginia Department of Wildlife Resources to support agency evaluation of area-of-impact determinations and associated survey requirements for projects comparable with those this study examines.]]></description>
      <pubDate>Sat, 23 May 2026 18:35:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2703847</guid>
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    <item>
      <title>A novel hybrid algorithm for damage detection in bridge foundations under complex underwater environments using ROV capture pictures</title>
      <link>https://trid.trb.org/View/2657161</link>
      <description><![CDATA[Underwater damage detection in bridge foundations is challenged by light attenuation, scattering, and noise. This study proposes an improved DeepLabV3 + method integrating optimized image enhancement and lightweight segmentation. Key innovations include: (1) A multi-stage enhancement strategy (Adaptive color enhancement-contrast limited adaptive histogram equalization（ACE-CLAHE）fusion, sharpness-weighted blending, adaptive filtering to restore colors, boost contrast, and highlight defects; (2) A MobileNetV4-based model with Dense Atrous Spatial Pyramid Pooling + Strip Pooling (DenseASPP+SP) modules and enhanced multi-scale attention(EMA)-convolutional block attention module attention(CBAM), balancing accuracy and efficiency. The method was evaluated in nine simulated aquatic environments, incorporating different turbidity agents (sediment, blue/red dye) and varying turbidity levels (low, medium, high). The experimental results show that the method achieves 89.69 % mIoU and 94.90 % mPA, surpassing the conventional DeepLabV3 + by 2.59 % and 1.82 %, respectively. In terms of lightweight design, compared to the original DeepLabV3 + model with Xception backbone, the proposed model reduces the parameter count by 12.30 % and the FLOPs by 87.70 %. Field tests at China’s South Dongting Bridge demonstrate robust performance, with 87.20 % IoU for cracks and 86.40 % for exposed rebar, outperforming manual inspections. This hybrid approach addresses critical limitations in underwater structural health monitoring through computational efficiency and reliable defect recognition.]]></description>
      <pubDate>Tue, 21 Apr 2026 14:30:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2657161</guid>
    </item>
    <item>
      <title>High-precision visual 3D measurement of bridge defects in high-turbidity water</title>
      <link>https://trid.trb.org/View/2692726</link>
      <description><![CDATA[Inspection of concealed underwater bridge piers faces challenges such as inaccessibility, poor visibility, and low measurement accuracy, limiting safety assessment and maintenance planning. This paper proposes a high-precision visual 3D measurement framework for detecting defects on underwater bridge piers in high-turbidity water, integrating a binocular system with a clean-water hood mounted on an ROV, a multi-medium refraction correction model, and a multi-sequence point cloud stitching method. Validation shows the clean-water hood preserves over 80% of point cloud reconstruction at 120 NTU turbidity, while refraction correction reduces checkerboard corner and cylindrical surface errors to within 0.2 mm and 0.8 mm, respectively. The point cloud stitching method improves accuracy by 50%. Field tests demonstrate over 60% improvement in defect size measurement along x and y directions. These results show that reliable 3D defect quantification is feasible in turbid underwater environments when turbidity, refraction, and stitching errors are jointly controlled.]]></description>
      <pubDate>Mon, 20 Apr 2026 09:25:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2692726</guid>
    </item>
    <item>
      <title>The application of structured light for external subsea pipeline inspection based on the underwater dry cabin</title>
      <link>https://trid.trb.org/View/2495452</link>
      <description><![CDATA[This study addresses the critical challenge of inspecting subsea pipelines in the highly turbid waters of the East China Sea, where visibility significantly hinders conventional methods. To overcome these limitations, the authors developed an advanced unmanned submarine light-scanning system that leverages structured light technology within a large-scale underwater dry cabin. This innovative setup enables high-precision, in-situ external inspections of pipelines by ensuring comprehensive scanning coverage even in poor visibility conditions. The core components of their system include the shipboard-controlled structured light scanning driving system (SLSDS) for precise motion control, enabling seamless full-pipeline coverage in a single deployment, and the shipboard electric control subsystem (SECS), which integrates power supply, sensing, communication, and control functionalities. Applied in the Zhoushan sea area, the dry-cabin scanning system demonstrated a 50–66.7 % reduction in inspection time and a tenfold improvement in data resolution over traditional technologies. These results highlight the system's effectiveness, efficiency, and safety advantages, offering a robust solution for pipeline inspections in offshore environments with compromised visibility. The system's capability to significantly enhance inspection accuracy and operational efficiency underscores its potential for broader application in similar high-turbidity settings.]]></description>
      <pubDate>Fri, 31 Jan 2025 11:45:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2495452</guid>
    </item>
    <item>
      <title>Assessing road construction effects on turbidity in adjacent water bodies using Sentinel-1 and Sentinel-2</title>
      <link>https://trid.trb.org/View/2467409</link>
      <description><![CDATA[Road construction significantly affects water resources by introducing contaminants, fragmenting habitats, and degrading water quality. This study examines the use of Remote Sensing (RS) data of Sentinel-1 (S1) and Sentinel-2 (S2) in Google Earth Engine (GEE) to do spatio-temporal analysis of turbidity in adjacent water bodies during the construction and operation of the E18 Arendal-Tvedestrand highway in southeastern Norway from 2017 to 2021. S1 radiometric data helped delineate water extents, while S2-Top of Atmosphere (TOA) multispectral data, corrected using the Modified Atmospheric correction for INland waters (MAIN), used to estimate turbidity levels. To ensure a comprehensive time series of RS data, the authors utilized S2-TOA data corrected with the MAIN algorithm rather than S2-Bottom Of Atmosphere (BOA) data. They validated the MAIN algorithm's accuracy against GLORIA (Global Observatory of Lake Responses to Interventions and Drivers) observations of surface water reflectance in lakes, globally. Subsequently, the corrected S2 data is used to calculate turbidity using the Novoa and Nechad retrieval algorithms and compared with GLORIA turbidity observations. Findings indicate that the MAIN algorithm adequately estimates water-leaving surface reflectance (Pearson correlation > 0.7 for wavelengths between 490 and 705 nm) and turbidity (Pearson correlation > 0.6 for both algorithms), determining Nechad as the more effective algorithm. In this regard, the authors used S2 corrected images with MAIN to estimate turbidity in the study area and evaluated with local gauge data and observational reports. Results indicate that the proposed framework effectively captures trends and patterns of turbidity variation in the study area. Findings verify that road construction can increase turbidity in adjacent water bodies and emphasis the employing RS data in cloud platforms like GEE can provide insights for effective long-term water quality management strategies during construction and operation phases.]]></description>
      <pubDate>Fri, 20 Dec 2024 10:25:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2467409</guid>
    </item>
    <item>
      <title>Reducing the Environmental Impact of Road Construction</title>
      <link>https://trid.trb.org/View/2309261</link>
      <description><![CDATA[Construction of roads exposes large areas of soil which can lead to high erosion rates. Current best management practices are good at keeping larger sized particles on-site, but smaller particles still remain a problem for construction site stormwater discharges. Turbid water leaving construction sites can have detrimental impacts for the surrounding environment, especially for aquatic organisms such as mussels. Polyacrylamide (PAM) has been shown to help reduce turbidity of construction site stormwater. Additionally, good vegetation cover can help reduce erosion from construction sites. Typically grass is planted, but there has been increased interest in using wildflowers as they provide food and habitat for a variety of pollinator insects. The authors' research evaluated the effectiveness of (1) I-540 sediment basins on Swift Creek water quality (turbidity and total suspended solids [TSS]) and (2) different wildflower mixes with and without compost and fertilizer as a stormwater control measure (SCM). The monitoring of sediment basins and Swift Creek investigated water quality being discharged from the sediment basins and water quality in Swift Creek on a storm event basis. The results from the sediment basin monitoring confirmed PAM application will reduce the turbidity and TSS of water in sediment basins. Without PAM application, turbidity levels being discharged were exceeding that of Swift Creek. However, Swift Creek often rose 6-7’ during rain events, and the turbid discharge from the construction site was rarely evident in the Swift Creek monitoring. These results suggest that (1) PAM should be consistently applied to get the clearest construction site stormwater discharge and (2) the flashiness of Swift Creek might be diluting the turbid water from the construction site. Second, the field studies considered vegetation cover from grass, wildflowers, and grass-wildflower mixes with and without compost (30% by volume) and/or fertilizer. It was found in both field studies that compost can be used without fertilizer and get the same vegetation cover as compost plus fertilizer, and compost had increased infiltration rates compared to no compost. Grass-wildflowers mixes and wildflowers preformed the same as grass for vegetation cover up to one year after planting. Vegetation establishment was best when excelsior matting was used as the ground cover compared to hydromulch. Overall, the results suggest that wildflowers and grass-wildflower mixes can be used with compost and no fertilizer to get good vegetation cover. Compost is recommended on less steep slopes as it can increaser the infiltration rate of the soil, which is necessary for SCMs. It is unknown if these practices could be applied to steeper (>10%) slopes. Pollinator friendly vegetation appears to be a viable option for an alternative ground cover on less steep slopes.]]></description>
      <pubDate>Wed, 27 Dec 2023 10:29:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2309261</guid>
    </item>
    <item>
      <title>Impact of high-speed turbidity currents on offshore spanning pipelines</title>
      <link>https://trid.trb.org/View/2247952</link>
      <description><![CDATA[Pipelines in the deep sea are at risk of damage due to submarine landslides, which can result in the loss of costly infrastructure and pollution stemming from hydrocarbon leaks. Submarine landslides can exhibit a wide range of flow characteristics, which in turn can affect how they interact with pipelines. Researchers have previously focused on pipelines impacted by submarine debris and/or mud flows described by non-Newtonian fluid rheological models and the laminar model. However, the impact of larger-scale and higher-speed submarine turbidity currents described by turbulence models on pipelines has been overlooked. In this study, the authors address this gap by utilizing a more accurate turbulence simulation method, namely, the large eddy simulation (LES) method, to analyze the effect of submarine turbidity currents on fixed spanning pipelines, and the authors validate the effectiveness of the proposed method via typical circular cylinder flow experiments and numerical simulations. The authors find that the lift force on the pipeline impacted by submarine turbidity currents under high-Reynolds number (Re) conditions is particularly significant relative to debris and/or mud flows under low-Re conditions. In parallel, the vortex shedding frequency increases with increasing Re, and the Strouhal number basically remains unchanged and ranges from 0.2–0.25 at 1,112 ≤ Re ≤ 333,559. Furthermore, the vortex structure and its arrangement behind the spanning pipeline become irregular with increasing Re, forming a turbulent vortex street, which reveals the mechanism of pipeline vibration. Finally, a methodology for predicting characteristic drag force and lift force coefficients is established for submarine pipeline design.]]></description>
      <pubDate>Thu, 21 Sep 2023 09:44:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2247952</guid>
    </item>
    <item>
      <title>Cohesive Sediment Resuspension: Experimentation and Analysis</title>
      <link>https://trid.trb.org/View/2153927</link>
      <description><![CDATA[The resuspension characteristics of cohesive bed sediment samples were assessed through laboratory experiments using a device called the "shaker." The samples were reconstructed in the laboratory from sediments obtained from ocean, estuarine, and riverine beds. Each sample was subjected to a series of increasing shear stresses, with each shear stress being maintained for a certain period. For each experiment, it was found that after a certain time into the resuspension process, the turbidity in the overlying water column reached a steady state indicating that net erosion at that time was equal to zero. The experimental observations affirm the theory that the bed armors after a finite amount of sediment has been resuspended into the water column due to the presence of underlying consolidated layers of greater shear strength. This prevents the underlying layers and particles from being exposed to the flow. At this point, the bed becomes armored. The steady state concentrations as well as the pre-steady state sediment concentrations in the overlying water column are influenced by the characteristics of the sediment bed and notably by the consolidation period of the sediment layers. For increasing bed shear stress, a longer time is required to attain steady-state concentrations in the water column. This is due to the variation in sediment strength with depth of the bed.]]></description>
      <pubDate>Tue, 25 Apr 2023 16:33:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/2153927</guid>
    </item>
    <item>
      <title>Optimizing Factors of Sediment Flocculation in Construction Site Runoff</title>
      <link>https://trid.trb.org/View/2012698</link>
      <description><![CDATA[Runoff from construction sites has received increased interest because high levels of turbidity can adversely impact aquatic life in receiving streams. The current practice is to use polyacrylamide (PAM) to flocculate and settle suspended particles prior to release of the storm water into the environment. Not much, however, is understood about factors that control the interactions between PAM and soil particles. The goal of this study was to both identify the factors that lead to optimal turbidity reductions and determine the best screening method that can be applied on construction sites. Soil from 22 counties in North Carolina were collected and tested for flocculation with 13 PAMs. These had charge densities from 0.0 to 30% and molecular weight in the ranges standard (STD), medium (SH), and high (VHM). During the preliminary screening, soil suspensions were prepared at 10 g/L and tested with PAM concentrations ranging from 1.0 to 250 mg/L. Upon hand shaking for 10 seconds and sedimentation for 30 seconds, the supernatant water turbidity was measured. Nonionic polymers were more effective in reducing turbidity than their anionic counterparts. PAM concentrations of 1.0 and 5.0 mg/L led to the lowest turbidities in all soils tested, and increasing PAM concentrations gradually resulted in increased turbidities. The effect of PAM molecular weight was found to be dependent on the charge density of the PAM in use. Larger turbidity reductions were observed in soils with higher clay and silt content relative to the sandy soils. Using a jar tester, the soil suspensions were also mixed with PAM at different intensities (G = 48, 130, and 640 s⁻¹) for periods of 20 to 600 seconds. The results indicated that mixing intensity plays a key role in the flocculation of sediments. Only G values of 130 and 640 s⁻¹ resulted in measurable turbidity reduction compared to the hand shaking test. The highest turbidity reductions were achieved at G = 130 s⁻¹. In contrast to the hand-shaking results, anionic PAMs were more effective at reducing turbidity than the nonionic one. This suggests that the choice of the most effective PAM also is dependent upon the screening method used. Increasing mixing time using the hand-shake test negatively affected the performance of the nonionic PAM with the soils with substantial clay and silt content. However, on the jar tester, an increase in mixing time resulted in reduced turbidity for all soils, regardless of the PAM used. To evaluate the effectiveness of PAM on the field relative to the laboratory experiments, two 17-meter-long model ditches were constructed at the Sediment and Erosion Control Research and Education Facility (SECREF) of the Crop and Soil Sciences Department of North Carolina State University. Four PAMs having charge density 0, 3, 10, and 30%, respectively, were used. Following the flocculation tests, conducted with 0, 1, and 3 check dams installed across the channels, the anionic PAM with 3% charge density consistently achieved the highest turbidity reductions in all soils tested. This suggests that the jar tests may better predict PAM performances on construction sites, compared to the hand-shake method. Furthermore, no significant difference was found between the effects of 1 and 3 check dams on turbidity reduction in all soils used for the tests.]]></description>
      <pubDate>Wed, 31 Aug 2022 11:17:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/2012698</guid>
    </item>
    <item>
      <title>Stream Flow Turbidity Monitoring during Construction</title>
      <link>https://trid.trb.org/View/1895366</link>
      <description><![CDATA[Any in-stream construction work requires permits from US Fish and Wildlife Service. The permitting is based on assumptions of turbidity extent and intensity, which impacts fish health and survival. The permitting restricts us to in stream work so having better quality turbidity data should open work windows, since current assumptions are very likely conservative. This is based on our experience.
Currently the study team assumes that turbidity could go 1000 feet downstream from cofferdam placement and other activities at levels that could cause harm to fish.  There is not a good body of literature to understand and support these assumptions.  If the study team can show that the effects are lesser in extent and severity, it will help us angle for more flexible in water work windows.  
Turbidity data collection supports the Maine Department of Transportation (MaineDOT) and the U.S. Fish and Wildlife Service programmatic agreement. Over the past two years, MaineDOT has hired Stantec to establish baseline data and determine future turbidity limits related to in-water construction events and their effects on Atlantic salmon (Salmo salar) and its critical habitat protected under the Endangered Species Act. This included turbidity data collection at two sites with in-water construction in 2020 and four project sites in 2021. 
The tasks in above mentioned work include establishing monitoring points prior to construction, collecting pre-construction (baseline) and syn-construction (during construction) turbidity samples, reviewing laboratory results, and providing a summary report for each project site. The water sample data collection will be performed as described in Appendix C and D of the “User’s Guide for the Maine Atlantic Salmon Programmatic Consultation (MAP) Version 1.0, March 2017”. 
The study team has developed turbidity monitoring protocols and recently hired Stantec to collect measurements. The study team has a protocol to follow to determine turbidity levels and there’s solid research on extent and severity that can cause harm to fish. However, turbidity is very specific to the location and stream bed composition among other things. More data collection at sites with in stream work is required and a comprehensive analysis of the data before impactful results (more flexible in stream work windows) can be determined.
]]></description>
      <pubDate>Fri, 03 Dec 2021 12:42:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/1895366</guid>
    </item>
    <item>
      <title>Hydrodynamic response of three- and four-column semi-submersibles supporting a wind turbine in regular and random waves</title>
      <link>https://trid.trb.org/View/1890630</link>
      <description><![CDATA[The experimental and numerical investigations of the hydrodynamic response on 3-column and 4-column semi-submersible floaters with the same displacement, supporting a wind turbine in regular and random waves have been carried out in the present study. Experiments have been conducted in a laboratory wave flume using 1:75 scale models with the catenary mooring system. The numerical simulations have been performed for identical waves using a panel method based hydrodynamic software, Ansys-AQWA. The simulations were performed on prototype and were validated against the scaled up measurements. The simulated responses compare reasonably well with experiments. It was found that the 4-Column semi-submersible has lower hydrodynamic response and it is more suitable to support a floating wind turbine as compared to 3-column semi-submersible.]]></description>
      <pubDate>Mon, 29 Nov 2021 11:32:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1890630</guid>
    </item>
    <item>
      <title>Evaluation of Concrete Grinding Residue (CGR) as a Soil Amendment for Erosion Control</title>
      <link>https://trid.trb.org/View/1853325</link>
      <description><![CDATA[Discarded or landfilled construction debris specifically from roadway projects may have untapped recycling potential for soil stabilization. However, blending some types of debris may not produce the desired results in all soils. Concrete diamond-grinding work on pavement projects generates a non-hazardous waste by-product called concrete grinding residue (or CGR). CGR has known cementitious characteristics that suggest a latent use as a soil-stabilizing amendment, especially for poor and problematic soils. In this study, Western Iowa loess soil was amended with CGR and subjected to rainfall simulations to measure the erodibility of several soil mixtures. To evaluate rain erosivity at different rainfall intensities, simulated rainfall experiments were performed on CGR-amended soils at 20% CGR dosages. This study reviewed different methods for collecting CGR discharge, discussed design, construction, and use of a uniform compaction apparatus; and analyzed stormwater runoff from soil forms tested in an indoor rainfall simulator. Pre-rainfall investigation of CGR-amended soils included standard Proctor compaction tests. Post-rainfall analysis included turbidity and total suspended-solids tests. Standard Proctor tests found the CGR-amended loess had only slightly different optimum moisture contents (OMCs) and maximum dry densities (MDDs) compared to untreated loess, while lab tests on rainwater runoff samples on CGR-amended loess exhibited dramatically higher turbidity and total suspended solids (TSS). Turbidity for CGR-amended loess increased from 2.5 to 7.5 times that of the loess (control) soil, while TSS increased from 1.8 to 4.7 times that of the control soil. Future lab-based wind simulations will be performed on CGR-amended soils to evaluate wind erosivity due to “wind whip” from passing vehicles. Additional Class A-1 highway shoulder soils will be tested for wind erodibility at several CGR dosages in lab-based simulations, and pre- and post-soil bearing strength and soil loss measurements will be used to evaluate the effects of CGR dosages on each shoulder aggregate.]]></description>
      <pubDate>Wed, 09 Jun 2021 17:19:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/1853325</guid>
    </item>
    <item>
      <title>Robustness verification of 3D pose estimation adaptive against lighting and turbid underwater varieties with active 3D marker and docking experiment in real sea</title>
      <link>https://trid.trb.org/View/1844466</link>
      <description><![CDATA[Aiming at developing underwater battery recharging system, the authors have been researching on automatic docking of an underwater robot using stereo-vision-based visual servoing and 3D marker. The docking function deems to be an important role not only for battery recharging but also for other advanced applications, such as information transmissions. The authors have proposed a optical docking system and conducted real sea experiments to verify the practicability of the proposed system composed of stereo-vision-based 3D pose (position and orientation) realtime measurement system. However, the proposed system sometimes failed the docking operation in the dusk and turbid environment since the recognition method lost the 3D marker in the natural lighting environment that changes every moment. In this paper, therefore, the authors proposed a new fitness function for improving the robustness against the lighting change. To improve the robustness, firstly, the authors propose a fitness function composed of color (HSV) and brightness evaluation for overcoming the difficulties to estimate in realtime 3D pose of the underwater vehicle in lighting and turbid varieties. Secondly, the authors modify the fitness function to improve sensitivity by adding a heuristic rule that increases the evaluation value when the all color balls of the model overlap real 3D marker in the camera images. This approach enables the docking system to apply to the natural lighting environment that changes every moment for increasing success rate of the docking operations. Thirdly, the effectiveness of the proposed fitness function adaptive to the changing lighting environment has been confirmed in the outdoor pool environment. Finally, the proposed docking system has been verified to be robust against lighting environment varieties, by successful repeated docking experiments in turbid environment with lighting condition changes from daytime to sunset in real sea.]]></description>
      <pubDate>Mon, 12 Apr 2021 17:48:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/1844466</guid>
    </item>
    <item>
      <title>Current-adaptive docking station for building submarine recharging system of underwater robot</title>
      <link>https://trid.trb.org/View/1844464</link>
      <description><![CDATA[Aiming at developing underwater battery recharging system, the authors have been researching on automatic docking of an underwater robot using stereo-vision-based visual servoing and 3D marker. The docking function deems to be an important role not only for battery recharging but also for other advanced applications, such as information transmissions. The authors have proposed a optical docking system and conducted real sea experiments to verify the practicability of the proposed docking system composed of stereo-vision-based 3D pose (position and orientation) realtime measurement system. The docking experiments have forced laboratory members to endure heavy burdens of preparing, conducting, and dismantling the experimental devices at sea, which hinders the efficiency of experiments at real sea. To improve the efficacy, firstly, the authors report that permanent stage for underwater robot experiments has been constructed on a shallow sea. Secondly, the authors propose a docking station that can adapt and change its docking direction to the current direction, through which the burden of controlling the underwater robot’s heading can be reduced. Thirdly, the effectiveness of the docking station adaptive to the changing current direction has been proven by successful repeated docking experiments in the environment with fluctuating current and turbidity disturbances in real sea. This also has shown that the combined system of the stereo-vision based 3D pose estimation and the current-adaptive docking station can improve the adaptive abilities against current changing disturbances, having shown the practicality of the combined system has been enhanced.]]></description>
      <pubDate>Mon, 12 Apr 2021 17:48:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/1844464</guid>
    </item>
    <item>
      <title>Non-Contact Scour Monitoring System for Railroad Bridges</title>
      <link>https://trid.trb.org/View/1747448</link>
      <description><![CDATA[Local scour poses potential damage to the bridge piers. Although researchers have developed instrumentation for scour detection around bridge piers, the current state-of-the-art practice relies upon visual inspection by divers. As a potential alternative to the traditional methods, this research explored the possibilities of using non-contact and remote sensing-based laser ranging technique for scour mapping and monitoring. This research report summarizes the existing methodologies along with required mathematical models, laboratory and field-based experiments. The first stage of the project analyzed the existing literature on scour and instrumentation to measure its rate. Then, the research continued exploring the factors affecting the demonstrated green laser-based non-contact measuring system including turbidity and refraction correction. As this non-contact technique will not have any contact with water to measure the scour, the laser shot from above water level will travel both air and water mediums that will require refraction correction to be applied to the derived topography. Scour is the process that typically occurs around the bridge piers which will require the green laser system to move around. Hence, this research demonstrated necessary mathematical models to apply refraction correction and direct georeferencing. The second stage of the project explored the feasibility of the developed research methodology in both laboratory and field setups. The laboratory setup included developing a scour hole based on published literature. The ability of the green laser to map the scour hole dimensions under varying turbidity conditions is demonstrated and presented in the report. Finally, the research team performed field testing on railroad and highway bridges in static and stop and go modes to demonstrate the typical procedure to retrieve underwater topography and scour using a green laser mapping system.]]></description>
      <pubDate>Thu, 29 Oct 2020 12:57:24 GMT</pubDate>
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