The bridge type in which the deck is located on the bottom of the main structure.

• A. Deck Bridges
• B. Through Bridge
• C. Half-Through Bridge
• D. Curved Bridges

Answer: (B)

The key idea is how the roadway sits within the supporting framework. When the deck is at the bottom of the main structure, the traffic sits inside the frame and you travel "through" the exposed sides of the bridge. That setup defines a through bridge: the main structural elements (the trusses or frames) rise above and to the sides of the deck, so you pass through the framework as you drive.

If the deck were on top of the supports, it would be a deck bridge, with the truss or frame underneath or at the sides but not surrounding the deck. If the deck sits roughly halfway up, you’d have a half-through bridge, where you’re partly enclosed by the structure. Curved bridges refer to the plan shape, not where the deck sits relative to the main structure.