Algorithm for queue estimation with loop detector of time occupancy in off-ramps on signalized motorways

G. Qian, B. Lee, E. Chung

Research output: Journal article publicationJournal articleAcademic researchpeer-review

11 Citations (Scopus)


Long traffic queues on off-ramps significantly compromise the safety and throughput of motorways. Obtaining accurate queue information is crucial for countermeasure strategies. However, it is challenging to estimate traffic queues with locally installed inductive loop detectors. This paper deals with the problem of queue estimation with the interpretation of queuing dynamics and the corresponding time-occupancy distribution over motorway off-ramps. A novel algorithm for real-time queue estimation with two detectors is presented and discussed. Results derived from microscopic traffic simulation validated the effectiveness of the algorithm and revealed some of its useful features: (a) long and intermediate traffic queues could be accurately measured, (b) relatively simple detector input (i.e., time occupancy) was required, and (c) the estimation philosophy was independent with signal timing changes and provided the potential to cooperate with advanced strategies for signal control. Some issues concerning field implementation are also discussed.

Original languageEnglish
Pages (from-to)50-56
Number of pages7
JournalTransportation Research Record
Issue number2278
Publication statusPublished - 12 Jan 2012
Externally publishedYes

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Mechanical Engineering


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