Vulnerability of pipeline systems were studied for the city of Adapazari based on available information on the performance of the water and sewage pipeline systems during 1999 Kocaeli, Turkey Earthquake. The water supply pipeline system in Adapazari experienced extensive damage. The main damage was observed in transmission and distribution systems primarily due to brittle asbestos cement (AC) pipes used in the system combined with the fracturing effect of ground deformations associated with liquefaction and softening of alluvial sediments. Recently, pipeline damage inventory was compiled based on repair reports and interviews with water works technicians. Since the entire system was replaced after the earthquake only limited number of repair reports was available. The geotechnical and geological site conditions were evaluated based on available borings, and in-situ tests. Vulnerability of water pipelines due to ground shaking and liquefaction was evaluated separately. Variation of earthquake characteristics on the ground surface was estimated based on 1D site response analyses using the outcrop motion recorded in Adapazari during the 1999 Earthquake as input motion. Liquefaction susceptibility was estimated based on a simplified liquefaction analysis and SPT blow counts obtained during the site investigations. Distribution of damage predicted by means of empirical vulnerability functions proposed in literature was compared to the pipeline damages observed during the 1999 Earthquake
