Forest Road Engineering Guidebook - Ministry of Forests

Forest Road Engineering Guidebook
Figure 15. Overlanding cross-section with corduroy.
Figure 16. Overlanding cross-section with inverted stumps.
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Geosynthetics can also be used to separate the underlying soil from the road
fill. This is a method for separating materials and reinforcing the subgrade,
but it requires careful preparation of the pioneer trail. A relatively smooth
surface is preferred to prevent underlying debris and rock puncturing the
geosynthetic. Where the risk of puncture is high, heavier geosynthetics are
required to cover coarse ballast rock, or stumps.
Geosynthetics can also be used to reinforce the road fill structure. The subgrade
and road fill must be built and compacted carefully to develop the necessary
friction (or cohesion) between the fabric and adjacent material. The
geosynthetic should be “anchored” within the structure to enable tensile