All of the following are important design principles for forest roads except:

Increasing traffic volumes is not considered an important design principle for forest roads. While it may seem beneficial in terms of accessibility or economic activity, focusing on traffic volumes can lead to negative impacts on the environment, such as increased soil compaction, erosion, and habitat fragmentation.

In forestry road design, the emphasis is placed on maintaining ecological balance and minimizing disturbances to the surrounding forest ecosystem. Important design principles include maintaining appropriate distances, which helps to manage the spacing between roads and resources, thus preventing overutilization of specific areas. Avoiding unstable soil types is critical to ensuring the longevity and safety of the roads, as unstable soils can lead to road failure and increased maintenance costs. Reducing soil disturbance is also vital, as it helps preserve soil health and water quality, preventing issues such as runoff and sedimentation.

In summary, while promoting road access is important, prioritizing ecological integrity and stability is fundamental in forest road design, making the focus on increasing traffic volumes counterproductive to good forestry practices.