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  • Terrain Coefficients for Predicting Energy Costs of Walking over Snow

    Abstract: Predicting the energy costs of human travel over snow can be of significant value to the military and other agencies planning work efforts when snow is present. The ability to quantify, and predict, those costs can help planners determine if snow will be a factor in the execution of dismounted tasks and operations. To adjust predictive models for the effect of terrain, and more specifically for surface conditions, on energy costs, terrain coefficients (ƞ) have been developed. By applying knowledge gained from prior studies of the effects of terrain and snow, and by leveraging those existing dismounted locomotion models, we seek to outline the steps in developing an improved terrain coefficient (ƞ) for snow to be used in predictive modeling. Using published data, methods, and a well-informed understanding of the physical elements of terrain, e.g., characterization of snow sinkage (z), this study made adjustments to ƞ-values specific to snow. This review of published metabolic cost methods suggest that an improved ƞ-value could be developed for use with the Pandolf equation, where z=depth (h)*(1 - (snow density (ρ0)/1.186)) and ƞ=0.0005z3 + 0.0001z2 + 0.1072z + 1.2604. This paper provides data-driven improvements to models that are used to predict the energy costs of dismounted movements over snow.
  • Snow-Covered Obstacles’ Effect on Vehicle Mobility

    ABSTRACT:  The Mobility in Complex Environments project used unmanned aerial systems (UAS) to identify obstacles and to provide path planning in forward operational locations. The UAS were equipped with remote-sensing devices, such as photogrammetry and lidar, to identify obstacles. The path-planning algorithms incorporated the detected obstacles to then identify the fastest and safest vehicle routes. Future algorithms should incorporate vehicle characteristics as each type of vehicle will perform differently over a given obstacle, resulting in distinctive optimal paths. This study explored the effect of snow-covered obstacles on dynamic vehicle response. Vehicle tests used an instrumented HMMWV (high mobility multipurpose wheeled vehicle) driven over obstacles with and without snow cover. Tests showed a 45% reduction in normal force variation and a 43% reduction in body acceleration associated with a 14.5 cm snow cover. To predict vehicle body acceleration and normal force response, we developed two quarter-car models: rigid terrain and deformable snow terrain quarter-car models. The simple quarter models provided reasonable agreement with the vehicle test data. We also used the models to analyze the effects of vehicle parameters, such as ground pressure, to understand the effect of snow cover on vehicle response.
  • PUBLICATION NOTICE: Seasonal Effects on Vehicle Mobility: High-Latitude Case Study

    Abstract: Seasonality plays a key role in altering the terrain of many military operating environments. Since seasonality has such a large impact on the terrain, it needs to be properly accounted for in vehicle dynamics models. This work outlines a variety of static and dynamic seasonal terrain conditions and their impacts on vehicle mobility in an austere region of Europe. Overall the vehicles performed the best in the dry season condition. The thaw season condition had the most drastic impact on mobility with all but the heavy tracked vehicle being almost completely NOGO in the region. Overall, the heavy tracked vehicle had the best performance in all terrain conditions. These results highlight the importance of incorporating seasonal impacts on terrain into NRMM or any vehicle dynamics model. Future work will focus on collecting more data to improve the empirical relationships between vehicles and seasonal terrain conditions, thereby allowing for more accurate speed predictions.
  • USACE Nashville District Hosts Leadership Training at Lock C in Indian Mound Tenn.

    INDIAN MOUND, Tenn. (July 13, 2020) -- Something huge made a commotion in the water, sending ripples in every direction, and making the hair on your skin stand on end.
  • PUBLICATION NOTICE: Improved Ribbon Bridge Structural Response Validation Testing

    Abstract: vehicles and trucks up to Military Load Capacity 96. The Bridge Supplemental Set (BSS) includes Bridge Erection Boats and an anchorage system to allow for the positioning and securing of the bridge in moving water. Designed to function as either a floating bridge or a raft, the IRB and BSS give military commanders multiple options with regards to the tactical river crossings. The US Army Engineer Research and Development Center (ERDC) was contracted by Product Manager Bridging to provide a structural analysis via high-fidelity numerical modeling of various IRB spans and water flow rates. To this end, a finite element model (FEM) of the IRB was constructed using field measurements of IRB interior bays. To ensure accurate structural response characteristics of the FEM and to build confidence in the simulation results, a validation test series was devised to generate empirical data to correlate against. This report documents the IRB structural response validation testing conducted at ERDC in March 2018. The data contained in this report was used to validate the IRB structural FEM.
  • PUBLICATION NOTICE: Structural Analysis of an Improved Ribbon Bridge Subjected to Hydrodynamic and Vehicular Loading

    Abstract: Structural modeling and simulations were performed to determine limit states of an Improved Ribbon Bridge (IRB) subjected to hydraulic and vehicle loadings. Measurements of as-built IRB bays were used to construct a three-dimensional, computer-aided design model. The model was used to create a computational finite element model (FEM) that was validated through correlations of simulation results and empirical data. The validated FEM was used to establish limit states (i.e., maximum current and vehicular loading conditions for 110 and 210 m IRB crossings). Analyses revealed that the primary structural failure mode was yielding in the steel pins that link IRB bays. Assuming the IRB is adequately restrained at the shores, a 110 m IRB can withstand currents up to 11 ft/s with no vehicle traffic; a 210 m IRB can endure up to 7 ft/s under the same conditions. For risk crossings, one Military Load Classification-70 vehicle on the bridge, 110 and 210 m IRBs can tolerate currents up to 9 and 7 ft/s, respectively. Under normal crossing conditions vehicle spaced 100 ft apart, a 110 m IRB has the structural capacity to endure currents up to 9 ft/s; the maximum current for a 210 m IRB is 5 ft/s.
  • NR 19-044: Corps reassigning control of Lock C to Fort Campbell

    NASHVILLE, Tenn. (Sept. 19, 2019) – The U.S. Army Corps of Engineers Nashville District is in the process of reassigning the Lock C site to the U.S. Army Garrison at Fort Campbell, Kentucky.
  • U.S Army Corps Awards Construction Contract for New VA Stockton Clinic

    VA Palo Alto Health Care System and the U.S. Army Corps of Engineers, Sacramento District awarded a $143.5 million construction contract on August 29 to S. J. Amoroso Construction Company of Redwood City, California, to build a new patient care facility near Stockton.
  • Corps awards $21.6M contract for Fort Hunter Liggett microgrid

    The U.S. Army Corps of Engineers Sacramento District awarded a $21.6 million construction contract April 12 to Ameresco of Framingham, Massachusetts to construct an electrical distribution microgird and 5 megawatt photovoltaic power generation at Fort Hunter Liggett. Ameresco is expected to break ground this spring and complete the project in 2021.
  • Corps awards $19.46M contract for Hill AFB fuel distribution system, pump house

    The U.S. Army Corps of Engineers Sacramento District awarded a $19.46 million construction contract March 29 to CTI Construction of Ogden, to replace an aging petroleum, oil and lubricants facility at Hill Air Force Base.