Roundabouts have become an alternative for traditional intersections due to the safer operational performance. Previous research has provided crash modification factors (CMFs) as a criterion based on before-after studies as to evaluate the safety performance of roundabouts. One drawback of assessment based on crash modification factors, however, is that a before-after study includes too many variations at a time that it only provides a general idea of the safety performance for roundabouts. Since the industrial world is interested in the safety outcome of converting traditional intersections to roundabouts, safety performance functions (SPFs) will provide more specific details on estimating crashes than that of crash modification factors. This thesis will adopt a similar methodology that has been used in the current Highway Safety Manual (HSM) to develop safety performance functions for roundabouts based on Oregon data. The outcome of this thesis will help the Oregon Department of Transportation (ODOT) to evaluate existing roundabouts in the State of Oregon. Furthermore, this thesis will function as an additional case study from Oregon to contribute to the national effort of evaluating the safety performance of roundabouts. / Graduation date: 2013