The Light Weight Deflectometer (LWD) was designed to test the compaction or bearing capacity of in-place aggregate base-course materials. This study evaluated the potential of the LWD to also characterize groomed snow and ice surfaces as the ability to characterize the strength, or bearing capacity, of winter surfaces is crucial for evaluation of vehicle mobility in cold climates.LWD tests were run on a variety of groomed snow and ice surfaces over asphalt pavement, gravel, and soil in the winter of 2018 in both Montana and Michigan. The LWD measures load and deflection, enabling calculation and backcalculation of stiffness parameters for the test surface layers. The initial results were reasonable for the snow layers analyzed. The Impulse Stiffness Modulus, calculated as the impact load divided by the deflection response, presents as a reasonable property for analysis, requiring no assumptions about other snow layer properties. However, the LWD components, specifically the rubber load buffers, may have issues with the effects of low temperature testing. These effects need to be considered when testing snow and ice surfaces. Additionally, the stress and compaction levels that most represent the conditions of interest for mobility purposes need to be determined. Specific and consistent LWD equipment configuration and test procedures need to be determined and implemented in further testing of winter surfaces.

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The Geospatial Remote Assessment for Ingress Locations (GRAIL) efforts under the Army Terrestrial-Environmental Modeling and Intelligence System (ARTEMIS) program have made significant advances in the remote assessment of terrain and soils for locating potential landing zone and drop zone (LZ and DZ) sites for military operations. The project identified sources of high-quality geospatial data, defined preprocessing requirements to produce global datasets for analysis, and created the GRAIL Tools software. The GRAIL Tools algorithms analyze and filter geospatial datasets to search for areas suitable for aircraft ground operations. GRAIL Tools then applies geometric criteria to determine if the required LZ/DZ will fit within the areas of suitable terrain and displays the potential LZs and DZs superimposed over geospatial imagery. Verification of the GRAIL Tools concept at Fort Hunter Liggett, California, developed and trained the suitability filter algorithms with regard to vegetation, obstructions, and soil strength. Further work served to enhance the algorithms and develop the full toolkit. Future work at a variety of sites, including work in northern regions with snow, ice, and freezing/thawing soils, will evolve the GRAIL Tools to handle the full spectrum of global terrain conditions for military operations. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.

The criteria for landing zones (LZs) and drop zones (DZs), also known as austere entry surfaces, are extensive and varied. They range from very specific guidance on required geometry to more general guidance on required bearing strength of unprepared surfaces, such as soil or ice, and the smoothness of those surfaces. Current practice for siting LZs and DZs includes site surveys by trained personnel, often in hostile environments. Additionally, with the continued advancement of image analysis, it may be possible to identify potential LZ and DZ sites remotely and thus to reduce the need to expose personnel to dangerous conditions. This review intends to summarize existing Federal, Department of Defense, and other criteria for unsurfaced, unimproved LZs and DZs. The purpose of the summary is to consolidate criteria so that the criteria may be considered in the process of developing and refining methods to remotely locate and assess potential LZs and DZs by using satellite imagery.