Researchers compared three different mobile tools to determine road strength.
For forest roads to be able to carry traffic, especially heavy vehicles such as those used for log transport, the forest roads need to have sufficient strength. Roads of high bearing strength are able to resist deforming when exposed to the mass transmitted through a tyre. However, it can be difficult to obtain an indication of the subgrade or pavement strength on site. The bearing capacity of forest roads also varies with different weather conditions and seasons. Due to cost limitations, forestry roads are often made with poor materials, and the constructed layers may be mixed with subgrade. A bearing capacity assessment can provide valuable information when trafficability is uncertain and rutting could occur. Researchers carried out bearing capacity measurements with a light falling weight deflectometer (LFWD), a dynamic cone penetrometer (DCP) and the conventional falling weight deflectometer (FWD). The aim was to compare their measurement results in relation to road characteristics and moisture conditions. The research was carried out on 35 test road sections in four consecutive springs and during one summer. The test road sections had measurement points both on the wheel path and the centre line. The results showed that light portable tools, the DCP and the LFWD, could be used in most cases to determine road surface strength, reducing the need for more expensive tests.
The research was titled “Applicability of portable tools in assessing the bearing capacity of forest roads”, and was published in Silva Fennica, Vol. 49(2) 2015. The authors were T Kaakkurivaara, N Vuorimies, P Kolisoja and J Uusitalo. Source: http://www.silvafennica.fi/article/1239