Mitigating Cascading Failures for Safety in Transportation Networks in the Era of Autonomous Vehicles

Bridge collapses, road closures, disruptions in the public transportation system, and major issues caused by autonomous vehicles (AVs) are everyday realities of our transportation infrastructure that not only cause inconvenience to the public but also constitute a major safety concern. When a particular component of the transportation system fails (e.g., due to an AV blocking a road), the failures and the associated congestion will likely be propagated to other parts of the transportation system, which may lead to further failures, and so on, potentially leading to a cascade of failures and a catastrophe in the whole city. A real-world example of this phenomenon took place on July 21, 2012, when a heavy rain shut down a metro line in Beijing and caused 100 bus routes to detour, skip stops, or cancel operation completely. Similarly, increasing deployment of AVs in the form of robotaxis by companies like Waymo and Cruise have not only led to several accidents but also events where seemingly confused AVs blocked certain roads for several hours. Cities such as Pittsburgh are particularly vulnerable to such cascade of failures and congestion propagation due to harsh weather conditions and existence of many bridges/tunnels creating bottlenecks. Given also the fact that increased congestion levels will likely lead to an increase in traffic incidents, there is a clear need for a better understanding of the impact of these cascading failures on the safety of the transportation system and the role that AVs play, both positive and negative, in them. This project aims to study the cascading effects of transportation network failures with an eye towards developing mitigation policies that maximize overall public safety. The research team will be particularly interested in accounting for the increased presence of AVs, both to understand their impact on initiating or amplifying these failures, and to reveal how AVs can help mitigate cascading failures. For example, a prior project supported by Mobility 21/Big Ideas fund laid out the initial work demonstrating how AVs can help reduce congestion more effectively by their ability to react in real time to vehicles around them, and their ability to be remotely and centrally controlled by fleet owners. Building on these initial results where the goal was to minimize the overall delay/congestion, this project will seek to reveal the impact of AVs on the safety of the overall transportation system. The plan is to develop a comprehensive model that quantifies the safety impact of different failure events while taking into account the potential cascading effects. For example, a stalled robotaxi blocking an intersection in San Francisco would initially pose a safety threat to vehicles and pedestrians in its vicinity. In addition, depending on how long it blocks the road, this event may cause a congestion which can then cascade to neighboring roads, potentially leading to increased accident rates in the entire city. To the best of the team's knowledge, this project will be developing the first set of metrics for quantifying the safety impacts of these failures with their cascading effects also included. The team would like to add that this project is synergistic with a concurrently submitted proposal entitled “Evaluating Autonomous Vehicles’ Safety Benefits in Mixed Autonomy Scenarios,” where the goal is to evaluate the safety impact of AVs from the perspective of their accident rates with other vehicles and human pedestrians. The current project on other hand focuses on revealing the overall safety impact of AVs including their impact on congestion and cascading road failures. As such, the two projects will nicely complement each other can be combined together at a total budget of $150,000 if so preferred.


  • English


  • Status: Active
  • Funding: $150000
  • Contract Numbers:


  • Sponsor Organizations:

    Carnegie Mellon University

    Safety21 National UTC for Promoting Safety
    Pittsburgh, PA  United States  15213

    Office of the Assistant Secretary for Research and Technology

    University Transportation Center Program
  • Managing Organizations:

    Carnegie Mellon University

    Safety21 National UTC for Promoting Safety
    Pittsburgh, PA  United States  15213
  • Project Managers:

    Stearns, Amy

  • Performing Organizations:

    Carnegie Mellon University

  • Principal Investigators:

    Yagan, Osman

  • Start Date: 20230701
  • Expected Completion Date: 20240630
  • Actual Completion Date: 0
  • USDOT Program: University Transportation Centers

Subject/Index Terms

Filing Info

  • Accession Number: 01900372
  • Record Type: Research project
  • Source Agency: Safety21
  • Contract Numbers: 69A3552344811
  • Files: UTC, RIP
  • Created Date: Nov 21 2023 8:14PM