What is a key benefit of using precast prestressed units in bridge design?

The key benefit of using precast prestressed units in bridge design is the lower overall weight of these components. Precast prestressed concrete elements are designed to be lighter than traditional cast-in-place concrete structures, which helps in reducing the load on the supporting infrastructure, such as piers and abutments. This reduction in weight allows for more efficient material use and potentially lowers construction and transportation costs. Additionally, the reduced dead load can facilitate the construction of longer spans, thus enabling more flexible design options in bridge planning.

The other options highlight potential benefits of precast units but do not capture the most significant advantage in the context of bridge design. While faster on-site assembly is a related benefit, the reduced weight is more fundamentally advantageous for overall structural efficiency. Improved aesthetic versatility can be a consideration in some cases, but it is not as critical as the impact of weight on structural performance. Greater resilience in extreme conditions may also be a consideration, but it varies widely depending on design and materials used, making it an unreliable blanket statement in this context.