The term BRIDGE PART can refer to a variety of components that make up a bridge. The four-letter solution SPAN refers to the main structure of the bridge, which is the part that spans the gap between two points. The four-letter solution HELM is the part of the bridge that supports the deck and is usually located at the ends of the SPAN. The nine-letter solution GUARDRAIL is the part of the bridge that provides safety for vehicles and pedestrians by preventing them from falling off the edge. The four-letter solution ARCH is a curved structure that is used to support the weight of the bridge. The five-letter solution TRUSS is a structural frame that is used to support the bridge's deck. Finally, the seven-letter solution TRESTLE is a type of bridge that consists of a series of vertical posts and horizontal beams.