Clear, blue river ice with water moving underneath is less strong than lake ice. What should the load be reduced by?

• A. 5%
• B. 10%
• C. 15%
• D. 20%

Answer: (C)

In terms of ice strength, clear, blue river ice is generally less robust due to the presence of water moving beneath it, which can create varying pressure and reduce the overall stability of the ice structure. When there is moving water, it adds dynamic forces that can lead to potential weaknesses, making it more prone to cracking or failure under load compared to static lake ice, which typically has a consistent and stable base.

To ensure safety when assessing load capacities on such ice, a common reduction in load is recommended. A 15% reduction is generally advised in these scenarios, acknowledging that even though it might appear solid, the underlying dynamics of flowing water can significantly compromise its strength. This reduction helps protect against unexpected failures that could lead to hazardous situations.

Thus, a 15% reduction adequately reflects the compromise in strength and is a standard safety measure when dealing with clear, blue river ice in contrast to the more stable lake ice.