The system is a real-time, adaptive traffic control system (or the Internet of Smart Intersections, in the sense of Smart IoT) that optimally schedules dynamic traffic flows in complex urban road networks, by integrating traffic theory with artificial intelligence (AI).

As the lead inventor of the system, Dr. Xie has created the core control engine (the brain) of the system, including schedule-driven intersection control (SchIC) and decentralized coordination mechanisms. He has also designed and realized all strengthening strategies of the system to enable its real-world operations.

Some extended work also includes: multi-modal urban traffic control (integrated with machine learning and computer vision techniques), integration with decentralized route choice framework, vehicle-to-infrastructure (V2I) communication with connected vehicles, and data-driven traffic management.

Real-World Deployments

– Deployed the initial smart traffic lights for a road network of nine intersections in the East Liberty neighborhood, Pittsburgh, PA. The initial system has been running since June 2012.

– Expanded the smart traffic signals further to include nine more intersections in the Bakery Square region, Pittsburgh, PA. The expanded system has been running since October 2013.

% Improvement Travel Time Speed # of Stops Wait Time Emissions
East Liberty 25.79% 34.02% 31.34% 40.64% 21.48%
Bakery Square 24.10% 35.41% 40.42% 41.59% 20.69%

 Core Control Engine of Surtrac Surtrac control region Surtrac field equipment

Media Coverage

This work has been broadly reported in media and news since its successful deployments in the real world.

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Main Publications
  • X. Xie, Y. Feng, S. Smith, and L. K. Head, “Unified route choice framework: Specification and application to urban traffic control,” Transportation Research Record, vol. 2466, pp. 105-113, 2014. [PDF] [DOI] [Bibtex]
    @Article{Xie2014bj,
    Title = {Unified route choice framework: Specification and application to urban traffic control},
    Author = {Xiao-Feng Xie and Yiheng Feng and S. Smith and K. Larry Head},
    Journal = {Transportation Research Record},
    Year = {2014},
    Pages = {105-113},
    PDF={http://www.wiomax.com/team/xie/paper/TRB14RCTC.pdf},
    DOI={10.3141/2466-12},
    Volume = {2466}
    }
  • X. Xie, S. Smith, T. Chen, and G. Barlow, “Real-time traffic control for sustainable urban living,” in IEEE International Conference on Intelligent Transportation Systems, Qingdao, China, 2014, pp. 1863-1868. [PDF] [PPT] [Bibtex]
    @InProceedings{Xie2014ITSC,
    Title = {Real-time traffic control for sustainable urban living},
    Author = {Xaio-Feng Xie and S. Smith and Ting-Wei Chen and G. Barlow},
    Booktitle = {IEEE International Conference on Intelligent Transportation Systems},
    Address = {Qingdao, China},
    Year = {2014},
    PDF = {http://www.wiomax.com/team/xie/paper/ITSC14.pdf},
    PPT={http://www.wiomax.com/team/xie/demo/ITSC14_demo_MMTC.pdf},
    Pages = {1863-1868}
    }
  • X. Xie, S. Smith, G. Barlow, and T. Chen, “Coping with real-world challenges in real-time urban traffic control,” in Transportation Research Board (TRB) Annual Meeting, Washington, DC, 2014. [PDF] [PPT] [DOI] [Bibtex]
    @InProceedings{Xie2014a,
    Title = {Coping with real-world challenges in real-time urban traffic control},
    Author = {Xiao-Feng Xie and S. Smith and G. Barlow and Ting-Wei Chen},
    Booktitle = {Transportation Research Board (TRB) Annual Meeting},
    Year = {2014},
    number={14-2103},
    PDF={http://www.wiomax.com/team/xie/paper/TRB14UTC.pdf},
    PPT={http://www.wiomax.com/team/xie/demo/TRB14_demo_Surtrac_Uncertainty.pdf},
    LNK={https://trid.trb.org/View/1288134},
    Address = {Washington, DC}
    }
  • X. Xie, S. Smith, G. Barlow, and Z. Rubinstein, “Accounting for real-world uncertainty in real-time adaptive traffic control,” The Robotics Institute, Carnegie Mellon University 2012. [PDF] [Bibtex]
    @TechReport{xie2012tr00,
    Title = {Accounting for real-world uncertainty in real-time adaptive traffic control},
    Author = {Xiao-Feng Xie and S. Smith and G. Barlow and Z. Rubinstein},
    Institution = {The Robotics Institute, Carnegie Mellon University},
    PDF={http://www.wiomax.com/team/xie/paper/ATCSTR12.pdf},
    Year = {2012}
    }
  • X. Xie, S. Smith, and G. Barlow, “Coordinated look-ahead scheduling for real-time traffic signal control,” in International Joint Conference on Autonomous Agents and Multiagent Systems (AAMAS), Valencia, Spain, 2012, pp. 1271-1272. [PPT] [DOI] [Bibtex]
    @InProceedings{Xie2012b,
    Title = {Coordinated look-ahead scheduling for real-time traffic signal control},
    Author = {Xiao-Feng Xie and S. Smith and G. Barlow},
    Booktitle = {{International Joint Conference on Autonomous Agents and Multiagent Systems (AAMAS)}},
    Year = {2012},
    Address = {Valencia, Spain},
    PPT={http://www.wiomax.com/team/xie/demo/AAMAS12_demo_Surtrac.pdf},
    LNK={http://dl.acm.org/citation.cfm?id=2343958},
    Pages = {1271-1272}
    }
  • X. Xie, S. Smith, L. Lu, and G. Barlow, “Schedule-driven intersection control,” Transportation Research Part C, vol. 24, pp. 168-189, 2012. [PDF] [DOI] [Bibtex]
    @Article{Xie2012,
    Title = {Schedule-driven intersection control},
    Author = {Xiao-Feng Xie and S. Smith and Liang Lu and G. Barlow},
    Journal = {Transportation Research Part C},
    Year = {2012},
    Pages = {168-189},
    Volume = {24},
    PDF={http://www.wiomax.com/team/xie/paper/TRC12.pdf},
    Doi = {10.1016/j.trc.2012.03.004}
    }
  • X. Xie, S. Smith, and G. Barlow, “Schedule-driven coordination for real-time traffic network control,” in International Conference on Automated Planning and Scheduling (ICAPS), Sao Paulo, 2012, pp. 323-331. [PDF] [PPT] [Bibtex]
    @InProceedings{Xie2012c,
    Title = {Schedule-driven coordination for real-time traffic network control},
    Author = {Xiao-Feng Xie and S. Smith and G. Barlow},
    Booktitle = {{International Conference on Automated Planning and Scheduling (ICAPS)}},
    Year = {2012},
    PDF={http://www.wiomax.com/team/xie/paper/ICAPS12.pdf},
    PPT={http://www.wiomax.com/team/xie/demo/ICAPS12_talk_Surtrac_Coordination.pdf},
    Address = {Sao Paulo},
    Pages = {323--331}
    }
  • X. Xie, G. Barlow, S. Smith, and Z. Rubinstein, “Platoon-based self-scheduling for real-time traffic signal control,” in IEEE International Conference on Intelligent Transportation Systems, Washington, DC, USA, 2011, pp. 879-884. [PDF] [PPT] [DOI] [Bibtex]
    @InProceedings{Xie2011,
    Title = {Platoon-based self-scheduling for real-time traffic signal control},
    Author = {Xaio-Feng Xie and G. Barlow and S. Smith and Z. Rubinstein},
    Booktitle = {IEEE International Conference on Intelligent Transportation Systems},
    Year = {2011},
    PDF={http://www.wiomax.com/team/xie/paper/ITSC11.pdf},
    PPT={http://www.wiomax.com/team/xie/demo/ITSC11_demo_PBSS.pdf},
    DOI={10.1109/ITSC.2011.6082849},
    Address = {Washington, DC, USA},
    Pages = {879--884}
    }

- Supported in part by the Robotics Institute, with support from the Heinz Endowments, the Hillman Foundation, and the R. K. Mellon Foundation.