For many years, reconstruction of roads has been built on the sampling of existing materials in the road structure. There are various methods to accomplish this, which means more or less damages in the road. From experience, we know that it may differ in material layer build up depending on where the roadbed samples are taken. Sides of the road may differ; slope and road surface often have different structure which makes it critical were sampling was done laterally in the road structure.
Efforts in a reconstruction is to obtain as similar final product as possible, i.e. about the same service life along the entire route. If you get significantly different results along the route it may result in maintenance operations must be carried out earlier or later than expected. Previously Scheduled actions can be if they are extensive clearly increase the cost of a LCC perspective (Life Cycle Cost), while oversizing on the other hand can result in increased costs in the construction phase. For Road Administration planning, it is important that the right action is taken. It must be a balance between representativeness, road safety and cost when selecting sampling method.
During three bearing capacity projects on existing roads in northern Sweden it has been sampled from both the road verge and the roadway. Sampling has been done to receive layer structure build-up from each sampling method on each section.
The purpose of the study is to examine whether there is a difference between the two sampling methods, and if there is a risk that the wrong reconstruction action is selected based on the results. The report presents results from sampling along three roads, road 779Andersfors–Storbrännan, 897 Ålund– Jakobsfors and 726 Bygdsiljum–Burträsk. The results have been analysed whether there are systematic differences or similarities between the location of sampling and how these are related to the Transport Administration's rules for sampling, as described in TDOK2014: 0151 "Sampling of unbound materials."