Identification and prioritization of key parameters of the Quality of Service at urban roundabouts based on a Delphi Survey

The ever-increasing use of roundabouts, especially in urban environment, has led to the development of an interest in obtaining an integrated measure of the operational efficiency and evaluation for that particular intersection type. According to the Highway Capacity Manual, roundabout evaluation is based on the quantitative measurements of the level of service. The same manual introduces the concept of quality of service as a measurement that corresponds to road users’perceived satisfaction. The main purpose of this study is twofold: a) to clarify the concept of QOS for roundabouts and b) to identify and prioritize the factors that affect road users’ perception. To address these issues, the aim of this study is to formulate a common list of factors affecting drivers’ behavior on urban roundabouts to guide stakeholders, engineers, transport designers in a structured base of familiarity in this specific intersection. To achieve this, the Delphi method is deployed in building consensus among independent experts, worldwide, in the field of transport. A predefined list of factors affecting driver’s behavior in roundabouts has to be evaluated and prioritized by the experts. The identification and prioritization of these factors provides a policy recommendation to better understand the issues that affect drivers’ behavior so that they can be addressed properly by the various stakeholders involving in roundabouts’ planning and operation.