Framework for Considering a Diverging Diamond Interchange to Improve Operations and Safety

Abstract

Innovations on intersection design have been the focus of recent developments in the US and around the world. The second installment of the Every Day Counts initiative (EDC-2) from the Federal Highway Administration (FHWA) promoted five new intersection designs. One of them was the Diverging Diamond Interchange (DDI). This innovative design has been implemented in several cities in the US to improve operations and safety. Puerto Rico is currently building its first DDI in the intersection of an arterial street and a freeway in the Municipality of Gurabo. This paper discusses the main characteristics of the DDI and presents a design framework from conception to implementation. This framework considers the geometric, environmental, and cultural influence in the design of a DDI, while also paying attention to the influence of non-motorized users and the continuous evaluation of the intersection by using driving simulation as part of the effective project implementation. Other topics discussed include safety evaluation, signaling, traffic influence, and the use of driving simulation into the determination of operational safety at a DDI. Also, the comparison between the conventional diamond interchange and the DDI, potential DDI issues from an operational point of view, and the objectives or goals of this type of intersection design are presented. A discussion of the benefits of using a driving simulator as a tool to evaluate a DDI and the importance of the data gathered in the process are also explained. Details of the implementation of this framework in Puerto Rico are presented as concluding remarks.