Paper presented at the 16th European-African Regional Conference of the ISTVS
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Title: Implementation of moving loads on ice in NRMM
Authors: Susan Frankenstein and Kathleen Jones
Abstract: Fording capabilities are common in cross country mobility models. They are limited in capability however due to their dependence on timely water level inputs and are best used for planning purposes based on monthly averages. Few, if any, include water velocity effects when crossing rivers and stream. Less common still are winter crossing considerations. To accurately predict vehicle speed on an ice cover the ice thickness, ice properties, and water depth are required. To solve for the speed an iterative process is needed which is prohibitive in mobility models. In order to implement in NRMM critical speed curves were generated for 37 ice thicknesses ranging from 0.01 – 5 m and 3000 water depths spanning 0.1 – 300 m. Using these curves, two equations, one for the steady state velocity and a second for the critical velocity as functions of water depth and ice thickness were developed. If the water depth is known, the final speed is the minimum of the two otherwise it is set to 6.7 m/s. In NRMM, the minimum ice thickness needed to support a single non-moving vehicle is calculated. Adjustments to the minimum ice thickness can be made for weaker ice. If the ice thickness is greater than the minimum thickness, then the speed and minimum vehicle spacing are calculated.
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