Smart and Scalable Urban Signal Networks

This system is a real-time adaptive traffic control system, which combines artificial intelligence (AI) and traffic theory to optimize highly dynamic traffic flow in urban road networks. The system (smart, adaptable traffic signals) is listed as 25 Great Things about Computer Science at Carnegie Mellon.

As the lead inventor of the system, Dr. Xie has created its core control engine, which combines schedule-driven intersection control (SchIC) with decentralized coordination mechanisms (in the sense of Internet of Smart Intersections, an instance of Smart IoT). He has also designed and realized the strengthening strategies to enable the real-world operations of the system in the field.

➥ Please visit here for our recent transportation research and studies on smart mobility and road safety beyond this work. Examples include:

  • X. Xie and Z. Wang, “Combined traffic control and route choice optimization for traffic networks with disruptive changes,” Transportmetrica B: Transport Dynamics, vol. 7, iss. 1, pp. 814-833, 2019. [DOI] [Bibtex]
    @Article{Xie2018RCTC2,
    Title = {Combined traffic control and route choice optimization for traffic networks with disruptive changes},
    Author = {Xiao-Feng Xie and Zun-Jing Wang},
    Journal = {Transportmetrica B: Transport Dynamics},
    Volume = {7},
    number={1},
    Pages = {814-833},
    Doi = {10.1080/21680566.2018.1517059},
    Year = {2019}
    }
  • X. Xie and Z. Wang, “Examining travel patterns and characteristics in a bikesharing network and implications for data-driven decision supports: Case study in the Washington DC area,” Journal of Transport Geography, vol. 71, pp. 84-102, 2018. [PDF] [DOI] [Bibtex]
    @Article{Xie2018Bike,
    Title = {Examining travel patterns and characteristics in a bikesharing network and implications for data-driven decision supports: Case study in the {Washington DC} area},
    Author = {Xiao-Feng Xie and Zun-Jing Wang},
    Journal = {Journal of Transport Geography},
    Volume = {71},
    Pages = {84--102},
    PDF={http://www.wiomax.com/team/xie/paper/JTRG18Pre.pdf},
    Doi = {10.1016/j.jtrangeo.2018.07.010},
    Year = {2018}
    }
  • X. Xie and Z. Wang, “SIV-DSS: Smart in-vehicle decision support system for driving at signalized intersections with V2I communication,” Transportation Research Part C, vol. 90, pp. 181-197, 2018. [PDF] [DOI] [Bibtex]
    @Article{Xie2018SIV,
    Title = {{SIV-DSS}: Smart in-vehicle decision support system for driving at signalized intersections with {V2I} communication},
    Author = {Xiao-Feng Xie and Zun-Jing Wang},
    Journal = {Transportation Research Part C},
    Volume = {90},
    Pages = {181--197},
    PDF={http://www.wiomax.com/team/xie/paper/TRC18Pre.pdf},
    Doi = {10.1016/j.trc.2018.03.008},
    Year = {2018}
    }
  • X. Xie and Z. Wang, “Multiscale crash analysis: A case study of integrating FARS, Maryland’s crash data, and Montgomery County’s traffic violation data,” in Transportation Research Board (TRB) Annual Meeting, Washington, DC, 2018. [PDF] [DOI] [Bibtex]
    @InProceedings{xie2018multiscale,
    title={Multiscale crash analysis: A case study of integrating {FARS}, {Maryland}'s crash data, and {Montgomery County}'s traffic violation data},
    author={Xie, Xiao-Feng and Wang, Zun-Jing},
    Booktitle = {Transportation Research Board (TRB) Annual Meeting},
    number={18-2283},
    Address = {Washington, DC},
    LNK={https://trid.trb.org/View/1495254},
    PDF={http://www.wiomax.com/team/xie/paper/TRB18.pdf},
    year={2018}
    }

Real-World Deployments

– (East Liberty) Deployed the the initial smart traffic lights for a network with nine intersections in the East Liberty neighborhood, Pittsburgh, PA. The system has been running since June 2012. Improvements of over 25% reductions in travel times, over 40% reductions in idle time, and a projected reduction in emissions of over 21% were achieved.

– (Bakery Square) Expanded the intelligent traffic signal control system further to include nine more intersections in the Bakery Square neighborhood, Pittsburgh, PA. The expanded system has been running since Oct 2013. Improvements of over 24% reductions in travel times, over 41% reductions in idle time, and a projected reduction in emissions of over 20% were achieved.

  • Xiao-Feng Xie, S. Smith, G. Barlow, and Ting-Wei Chen. Coping with real-world challenges in real-time urban traffic control. In Transportation Research Board (TRB) Annual Meeting, number 14-2103, 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}
    }
  • Xiao-Feng Xie, S. Smith, Ting-Wei Chen, and G. Barlow. Real-time traffic control for sustainable urban living. In IEEE International Conference on Intelligent Transportation Systems, pages 1863-1868, Qingdao, China, 2014. [PDF] [PPT] [Video] [DOI] [Bibtex]
    @InProceedings{Xie2014ITSC,
    Title = {Real-time traffic control for sustainable urban living},
    Author = {Xiao-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},
    VID={https://www.youtube.com/watch?v=UBu6QtNiJVY},
    DOI={10.1109/ITSC.2014.6957964},
    Pages = {1863-1868}
    }
  • Xiao-Feng 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), pages 1271-1272, Valencia, Spain, 2012. [PDF] [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},
    PDF={http://www.wiomax.com/team/xie/paper/AAMAS12.pdf},
    PPT={http://www.wiomax.com/team/xie/demo/AAMAS12_demo_Surtrac.pdf},
    LNK={http://dl.acm.org/citation.cfm?id=2343958},
    Pages = {1271-1272}
    }
  • Xiao-Feng Xie, S. Smith, Liang Lu, and G. Barlow. Schedule-driven intersection control. Transportation Research Part C, 24: 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}
    }
  • Xiao-Feng Xie, S. Smith, and G. Barlow. Schedule-driven coordination for real-time traffic network control. In International Conference on Automated Planning and Scheduling (ICAPS), pages 323-331, Sao Paulo, Brazil, 2012. [PDF] [Video] [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},
    VID={https://www.youtube.com/watch?v=d_BCzByquGg},
    Address = {Sao Paulo, Brazil},
    Pages = {323--331}
    }
  • Xiao-Feng 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, pages 879-884, Washington, DC, USA, 2011. [PDF] [Video] [DOI] [Bibtex]
    @InProceedings{Xie2011,
    Title = {Platoon-based self-scheduling for real-time traffic signal control},
    Author = {Xiao-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},
    VID={https://www.youtube.com/watch?v=gkDsgMG1eg0},
    DOI={10.1109/ITSC.2011.6082849},
    Address = {Washington, DC, USA},
    Pages = {879--884}
    }

– This work was supported in part by the Robotics Institute of CMU, with support from the Hillman Foundation, the Heinz Endowments, and the R. K. Mellon Foundation.