______ decks are found on many older bridges and movable bridges.

______ decks are found on many older bridges and movable bridges.

• A. Concrete
• B. Timber
• C. Steel
• D. Masonry

Answer: (C)

Steel decks are found on many older bridges and movable bridges because steel provides the combination of strength, durability, and compatibility with moving spans that these structures require. On movable bridges such as bascules or lifts, the deck must endure frequent opening and closing, heavy wheel loads, and precise alignment with the mechanism. Steel decks—often as plates or panel systems—offer high load capacity while being relatively lightweight, easy to fabricate and replace, and able to be integrated directly with the girders and operating equipment without adding excessive stiffness or weight. Timber decks can wear out and rot under weather and traffic, concrete decks are more typical of newer or rehabilitated bridges, and masonry decks are not practical for modern movable or long-span bridges. So steel decks best fit the needs of older bridges and movable types.

Steel decks are found on many older bridges and movable bridges because steel provides the combination of strength, durability, and compatibility with moving spans that these structures require. On movable bridges such as bascules or lifts, the deck must endure frequent opening and closing, heavy wheel loads, and precise alignment with the mechanism. Steel decks—often as plates or panel systems—offer high load capacity while being relatively lightweight, easy to fabricate and replace, and able to be integrated directly with the girders and operating equipment without adding excessive stiffness or weight. Timber decks can wear out and rot under weather and traffic, concrete decks are more typical of newer or rehabilitated bridges, and masonry decks are not practical for modern movable or long-span bridges. So steel decks best fit the needs of older bridges and movable types.