What is a key characteristic of multi-girder bridges?

Answer: B — They can span over 500 feet.

A key characteristic of multi-girder bridges is their ability to span long distances, often exceeding 500 feet. These bridges utilize multiple girders to distribute loads more evenly and provide greater structural integrity, which allows them to cover substantial spans. The design of multi-girder bridges enables them to support heavier loads and withstand various environmental factors, making them suitable for various applications, including highway overpasses and railways. The other options do not accurately reflect the characteristics of multi-girder bridges. For example, while some multi-girder bridges may incorporate wood as a material, they are not typically made entirely of wood; rather, they are more commonly constructed from steel or concrete. Furthermore, multi-girder bridges are not limited to shorter spans; they are specifically designed to handle longer spans efficiently. Lastly, the definition of a multi-girder bridge inherently involves more than one girder; therefore, stating that they consist of only one girder contradicts their fundamental design.