Safe Operations at Roadway Junctions - Design Principles Drawn from Automated Guideway Transit

J. Lott, Stanley Young, Lei Zhu

Research output: NRELNewsletter


The complexity of major roadway signalized intersections within an urban area can be quite challenging when automobile, pedestrian/bicycle, and transit modes are all vying for right of way, and even more so when adding automated/autonomous vehicles (AVs) to the mix. Even without automated vehicles, about 36% of collisions occur at intersections, with most occurring upon left turns (22.2%) or crossing over (12.6%), and only a small percentage (1.2%) while turning right at an intersection. Of this 36%, about half (52.5%) of those vehicles were traveling through a signalized intersection. AV operation for the purpose of public transportation must operate safely in dense urban districts where their services are needed most, while mitigating any crash hazards. The authors have proposed in a paper recently published in the SAE International Journal of Advances and Current Practices in Mobility that safely navigating such complexity calls for enhanced roadway infrastructure. It is asserted that advanced sensing technology combined with digital communications is necessary not only to enable safe AV operations in dense urban environments, but also to address current safety issues with conventional traffic. Given this high number of collisions that occur at intersections - with failure to yield being the primary cause of crashes - intersection safety that provides an additional layer of protection from vehicles that fail to yield is critical for effective AV deployment.

NREL Publication Number

  • NREL/NS-5400-83289


  • automated mobility districts
  • automated vehicles
  • infrastructure perception
  • intelligent infrastructure
  • smart infrastructure


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