Which pair of loads are both considered secondary live loads?

• A. Vehicles and Parapets
• B. Dead Load and Fatigue
• C. Pedestrian Load and Ice Pressure
• D. Primary Live Load and Ice Pressure

Answer: (C)

Secondary live loads are the extra, non-primary live loads a bridge may experience in service, beyond the main traffic the structure is designed to carry. Pedestrian load qualifies as a live load because it comes from people crossing, but it is typically not the primary design load; it’s an additional, less frequent demand that must be accounted for. Ice pressure is a seasonal, transient load on the deck that isn’t a permanent dead load, so it’s treated as another secondary live load in many design guides. Together, these two loads represent secondary live loads because they are variable and not the main design vehicle load.

The other options mix different categories: vehicles are a primary live load, parapets contribute to dead/structure loads rather than a live load, dead load and fatigue aren’t live loads, and including the primary live load disqualifies them from being both secondary.