The article proposes an approach to determine relative terrorist-related security risk levels of pipeline transportation. Pipeline routes are divided into smaller route segments. Subsequently, likelihood scores of possible terrorist-related incidents are determined per route segment and per transport route. A likelihood grade (LG) per pipeline transport route is determined. Next, the consequences of incident scenarios are quantitatively assessed and a consequence grade (CG) is determined. Using the LGs and CGs, pipeline routes terrorist risk levels are determined. This leads to a user-friendly threat assessment tool, which can be used by pipeline security management to screen pipeline networks for terrorist-related risks. © 2012 Macmillan Publishers Ltd.