Natural gas as a fuel is supplied in the most populous urban areas with the risk threatening public safety managed properly. Regulatory authorities in many countries are moving away from prescriptive approaches for keeping natural gas pipelines safe. As an alternative, risk management based on a quantitative assessment is considered to improve the level of safety. This work focuses on the quantitative risk assessment for the natural gas pipelines network and introduces parameters of fatal length and cumulative fatal length. The fatal length is defined as the integrated fatality along the pipeline associated with hypothetical accidents. The cumulative fatal length is defined as the length of pipeline section in which an accident leads to N or more fatalities. These parameters can be calculated easily within a geographic information system (GIS). For a new gas pipeline that will be installed in a suburban area, the risks are estimated simply in a few hours by using this method. This quantitative risk assessment may be useful for risk management during the planning and building stages of a new pipeline, modification of the pipeline, and to lower the risk of a buried pipeline network.