What factor primarily contributes to uneven compaction in small fills?

Uneven compaction in small fills is primarily influenced by the size of the area. When working with smaller fills, the compactness of the soil can be affected by how the compaction equipment interacts with the area being worked on. Smaller areas may not allow for consistent application of pressure or uniform access of compaction equipment, leading to variations in soil density and compaction levels.

In contrast, larger areas tend to provide a more uniform distribution of weight and pressure across the fill material, which helps achieve consistent compaction. Factors such as soil type, moisture content, and the amount of traffic certainly play a role in the overall compaction process, but in the context of small fills, the size of the area directly impacts the compaction efficiency and uniformity.