EuroGeo 6 25-28 September 2016 1147 1 INTRODUCTION The technique of soil-improvement using geosynthetics is extensively used in the construc- tion of unpaved roads. Geosynthetic reinforcement becomes increasingly effective as the dis- placements become large, so when the substantial surface rutting is acceptable. This assump- tion is usually correct in the case of unpaved structures. Unpaved roads are usually used for temporary roads. They remain in service for only short periods (often less than 1 year), and are usually subjected to low volume traffic (less than 10000 load applications). This kind of roads include detours, access roads and tracks, low cost roads and stabilized working bases for heavy machinery. When the subgrade is weak, due to its poor consistency and high com- pressibility, generally, a geosynthetic reinforcement (geogrid and/or geotextile) is placed over the subgrade followed by a compacted granular fill layer. This technique is particularly effective because the performances of reinforced unpaved roads are enhanced by reducing permanent rut deformation for a given number of axle loads. Therefore the goals of geosyn- thetic reinforcements are an increase of the road service life; a decrease of the construction cost by decreasing the base layer thickness (if the cost of the geosynthetic reinforcement is less than the cost of the saved base material); a decrease of the time required for the construc- tion and of the periodic maintenance interventions. In literature, on this topic, several meth- ods for unpaved road design as well as some numerical and experimental works have been presented. Conventional design procedures differ for subgrade failure mode, type of load dis- tribution and type of reinforcement support mechanism. This paper deals with the results of a Reinforced unpaved roads: parametrical analysis of design procedures L.S. Calvarano* “Mediterranea” University of Reggio Calabria, Italy (lidia.calvarano@unirc.it) N. Moraci & G. Leonardi & R. Palamara “Mediterranea” University of Reggio Calabria, Italy (nicola.moraci@unirc.it), “Mediterranea” University of Reggio Calabria, Italy (giovanni.leonardi@unirc.it), “Mediterranea” University of Reggio Calabria, Italy (rocco.palamara@unirc.it ABSTRACT: Geosynthetics are commonly used for unpaved roads with a low volume of traffic. Unpaved roads, consisting of unbound granular bases overlying cohesive subgrades, are usually temporary roads, rural roads and haul roads. These roads are subject to problems like excessive rutting and mud-pumping, making the road unusable for the traffic. Conven- tional design procedures differ for subgrade failure mode, type of load distribution and type of reinforcement support mechanism. This paper deals with the results of a parametric analy- sis varying soil and geosynthetic mechanical properties, allowable rut depth and traffic condi- tions. The main objective of the present study is to compare these different design procedures aimed at estimating the base thickness required for unpaved roads reinforced with different geosynthetics. Keywords: unpaved road, geosynthetic, reinforcement mechanisms type, design methods.