Enhancing privacy and accuracy in probe vehicle-based traffic monitoring via virtual trip lines

Baik Hoh, Toch Iwuchukwu, Quinn Jacobson, Daniel Work, Alexandre M. Bayen, Ryan Herring, Juan Carlos Herrera, Marco Gruteser, Murali Annavaram, Jeff Ban

Research output: Contribution to journalArticlepeer-review


Traffic monitoring using probe vehicles with GPS receivers promises significant improvements in cost, coverage, and accuracy over dedicated infrastructure systems. Current approaches, however, raise privacy concerns because they require participants to reveal their positions to an external traffic monitoring server. To address this challenge, we describe a system based on virtual trip lines and an associated cloaking technique, followed by another system design in which we relax the privacy requirements to maximize the accuracy of real-time traffic estimation. We introduce virtual trip lines which are geographic markers that indicate where vehicles should provide speed updates. These markers are placed to avoid specific privacy sensitive locations. They also allow aggregating and cloaking several location updates based on trip line identifiers, without knowing the actual geographic locations of these trip lines. Thus, they facilitate the design of a distributed architecture, in which no single entity has a complete knowledge of probe identities and fine-grained location information. We have implemented the system with GPS smartphone clients and conducted a controlled experiment with 100 phone-equipped drivers circling a highway segment, which was later extended into a year-long public deployment.

Original languageEnglish (US)
Article number5871633
Pages (from-to)849-864
Number of pages16
JournalIEEE Transactions on Mobile Computing
Issue number5
StatePublished - May 2012


  • Algorithms
  • GPS
  • data integrity
  • design
  • experimentation
  • privacy
  • security
  • traffic

ASJC Scopus subject areas

  • Software
  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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