| "To avoid the risk of landslides, which can cause destructive damages to road structures such as tunnels and bridges, the risk should be understood at initial stages of highway planning. The risk of bedrock landslides and other kinds of landslides, which are difficult to detect since they show no clear landslide landforms should be carefully examined by: 1) Investigating the possibility of landslide when deformation of road structures is found over a large area even when the bedrock is relatively fresh, 2) Conducting field exploration of the upper slopes exceeding the range of assumed landslides, for at least twice the width of the affected section and up to the ridge when possible, to check deformation of the slope attributable to landslides, when a landslide is suspected for, and 3) Conducting field surveys by experts of landslide. When the field surveys show suspicion for landslide, precise surveys in order to detect landslide should be conducted by preparing precise topographic maps using laser profilers and analyzing the topograohy." |
