What is a primary characteristic of deep foundation systems like caissons?

Deep foundation systems, such as caissons, are designed to transfer structural loads deep into the ground, which is their primary characteristic. This is particularly important when building on sites with weak surface soils that cannot adequately support the weight of structures. By extending the foundation deep into more stable soil layers or bedrock, caissons provide the necessary support and load-bearing capacity required for tall buildings, bridges, and other heavy structures.

The ability to transfer loads deep into the ground also helps mitigate issues related to settlement and stability, especially in challenging soil conditions. This ensures that the structural integrity of the building remains sound over time, as the loads are safely distributed to layers that can support them effectively.

The other options, while they might describe features related to different types of foundations, do not accurately define caissons' function or typical usage.