Tehran-Fasham road is one of the busiest access roads to the ski resorts situated on the north of Tehran province. Due to rockfall and slope instability of the road-side mountain each year there is loss of human life as well as financial losses. This paper presents the assessment of the rockfall hazards using innovative numerical and geotechnical methods. This includes a special laser scanning and mapping of all potential rockfall zones to find the most probable block size together with a corresponding 2Dtrajectory analysis and obtaining the amount of energy released by the projectile at the moment of impact with the barrier. Finally rockfall barriers with elastic and plastic nature were used for protection against rockfall hazards. The design of the system was done using Rockfall 6.1 software. When the project was completed at the delivery time a test of performance of the system was done on one of the executed zones. The rockfall barrier successfully neutralized the 4 tonne block and this is an indication of the reliability of this system which is widely used around the world.
Tehran-Fasham road in Kamarkhani area which is approximately 700 meters long extends from the beginning of Kamarkhani area to its end. This area is one of the most dangerous areas in terms of rockfalls in normal situations and especially after rainfalls or a change in temperature. The passing road in this area which has the elevation of approximately 1770 to 1790 meters from sea level is beside cliffs that are exposed to air that lead to Alborz mountains. Due to this exposure to air, the number of rocks was to the degree that the surface of the adjacent road was highly damaged causing different elevations and holes from the impact of falling rocks. Residents of the surrounding towns used to avoid driving through this road. Existence of a river with debris flow trend on the eastern wing of the road extending 700 meters and also the low width of the road that in some spots is only 6.5 meters added to this prevalent problem. In addition to the above, there is a high traffic volume because there are some important tourist areas at the end of Tehran-Fasham road and this is an evidence to the necessity of doing studies and making the road safe. Based on some statistics in the past years the number of vehicles passing through this road on Thursdays and Fridays (the weekend) sometimes exceeded hundred thousand that based on this figure the studies for the project of rockfall control and road safety in the form of EPC for the Kamarkhani area started that ultimately the goal was to create maximum safety for the road adjacent to the cliffs with rockfall potential. In this article technical aspects regarding studying and designing the rockfall barrier system from the beginning until the time that the executed system was tested has been discussed.