Optimization-based assisted calibration of traffic simulation models

David K. Hale, Constantinos Antoniou, Mark Brackstone, Dimitra Michalaka, Ana T. Moreno, Kavita Parikh

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Use of traffic simulation has increased in recent decades; and this high-fidelity modelling, along with moving vehicle animation, has allowed transportation decisions to be made with better confidence. During this time, traffic engineers have been encouraged to embrace the process of calibration, in which steps are taken to reconcile simulated and field-observed performance. According to international surveys, experts, and conventional wisdom, existing (non-automated) methods of calibration have been difficult or inadequate. There has been extensive research on improved calibration methods, but many of these efforts have not produced the flexibility and practicality required by real-world engineers. With this in mind, a patent-pending (US 61/859,819) architecture for software-assisted calibration was developed to maximize practicality, flexibility, and ease-of-use. This architecture is called SASCO (i.e. Sensitivity Analysis, Self-Calibration, and Optimization). The original optimization method within SASCO was based on "directed brute force" (DBF) searching; performing exhaustive evaluation of alternatives in a discrete, user-defined search space. Simultaneous Perturbation Stochastic Approximation (SPSA) has also gained favor as an efficient method for optimizing computationally expensive, "black-box" traffic simulations, and was also implemented within SASCO. This paper uses synthetic and real-world case studies to assess the qualities of DBF and SPSA, so they can be applied in the right situations. SPSA was found to be the fastest method, which is important when calibrating numerous inputs, but DBF was more reliable. Additionally DBF was better than SPSA for sensitivity analysis, and for calibrating complex inputs. Regardless of which optimization method is selected, the SASCO architecture appears to offer a new and practice-ready level of calibration efficiency.

Original languageEnglish
Pages (from-to)100-115
Number of pages16
JournalTransportation Research Part C: Emerging Technologies
Volume55
DOIs
StatePublished - 1 Jun 2015
Externally publishedYes

Keywords

  • Assisted calibration
  • Calibration
  • Microscopic simulation
  • SPSA
  • Simulation-based optimization
  • Traffic simulation

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