For architectural structures like bridges the U.S. Copyright Office lists them as ineligible for copyright registration:
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Ineligible Building Designs
The following building designs cannot be registered:
• Designs that were constructed, or whose plans or drawings were published,before December 1, 1990
• Designs that were unconstructed and created in unpublished plans or drawings on December 1, 1990, and were not constructed on or before December 31, 2002
• Structures other than buildings, such as bridges, cloverleafs, dams, walkways, tents, recreational vehicles, mobile homes, and boats
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Anyway to stay safe is always better to avoid anything from the real world that is not absolutely a generic type … like fruits meshes that afaik can’t be copyrighted that easily… obviously avoiding adding a real world brand name on them.