A major problem that faces the highways engineer is the failure of roads side slopes, specially after being opened to traffic. In most cases this obstacle is treated either by building gravity or reinforced concrete walls. In fact, these types of retaining structures have proven successful if they are well designed and constructed. However; they are time consuming and they necessitate excavating large volumes of soils, in some cases requiring the construction of a temporary retaining system and importing a better sandy soil for refilling behind the wall.
Other methods of earth slope stabilization are by geosynthetics reinforcement or by nailing. The purpose of this study is mainly to highlight nailing as in situe reinforcement technique that does not need any deep cutting of side slopes and in most cases does not cause any disturbance of road pavement.
The principles of side slope nailing are firstly reviewed. Secondly, a laboratory model of sand slope has been constructed and tested for cyclic loads simulating traffic loads. The slope face deformation have been recorded before and after nailing with three types of nails of different rigities, lengths, inclinations and spacing. It was found that reinforcing highway's side slopes by nailing is a new promising technique, it can help in solving the problem of side slopes failture due to traffic loads. Our lab experience with this stabilizing method has established a significant improvement of side slope safety by nailing.