CAVs and Roundabouts: Research on Traffic Impacts and Design Elements

Well-designed roundabouts improve capacity, safety performance and offer other benefits such as air quality. However, the development of the existing roundabouts, combined with gradual changes in vehicle characteristics means that these layouts need to be examined to a wider range of scenarios. Nowadays, the modern automotive industry is facing a revolution that is possible to lead to the introduction of Automated Vehicles for use in everyday traffic. According to this framework, it is anticipated that Connected and Autonomous Vehicles (CAVs) will create a challenge for transport and network operators in the coming decade. It is claimed that CAVs have the opportunity to reduce emissions and the cost of travel, increase road safety, the shared mobility, as well as the capacity of the road networks. Research on this sector and especially on the impacts by the use of CAVs on roundabouts is limited. In the light of the above, this paper investigates the traffic impacts, as well as the possible changes in the design elements needed by the implementation of automated and connected vehicles on double lane roundabouts. As the use of CAVs is still at an experimental stage, the methodology of micro-simulation was selected to be used for the purposes of the study. The effectiveness of the proposed approach lies on the ability of the simulation of driving behavior characteristics of autonomous vehicles. The modification of particular vehicle behavior parameters can represent a plausible future for CAVs. As a result, two double-lane roundabouts were investigated in traffic scenarios in order to evaluate the traffic impacts by the use of conventional and fully autonomous cars. The case study roundabouts located in the cities of Larissa and Volos were selected for the purposes of the study. Roundabouts’ performance was filmed with the use of an Unmanned Aerial Vehicle (UAV) during morning and evening peak periods in the Christmas holidays of 2018. Video processing, as well as semi-automatic data analysis were performed by using the open source software Tracker Video Analysis and Modeling tool, which allowed the extraction of the traffic kinematic characteristics and parameters. The interpretation of the processed data was valuable in order to understand the behavior and trend of the road users. Their applicability was useful for the development, calibration and validation of the micro-simulation traffic models by the use of PTV Vissim 11 traffic simulation software. Subsequently, the development of traffic scenarios by the modeling of automated and connected vehicles on the network allowed the investigation and evaluation by varying penetration rates of autonomous vehicles, as well as the determination of the traffic impacts on the network. The trajectories of the vehicles were able to extract useful data for the calculation of emissions and capacities. Finally, optimal changes in roundabout design were critically reviewed according to the results. Peering into the future is a fun exercise, but there is a need for cities and engineers to be prepared for a future that might be not too far away from now. Extensive research in the possible opportunities, as well as in the key challenges that autonomous vehicles are able to introduce, should be done.


  • English

Media Info

  • Media Type: Digital/other
  • Pagination: 18p
  • Monograph Title: European Transport Conference 2019

Subject/Index Terms

Filing Info

  • Accession Number: 01749307
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 13 2020 3:51PM