A stochastic delay model for signal-free intersections

Alireza Soltani, David M. Levinson and Mohsen Ramezani
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Mohsen Ramezani: TransportLab, School of Civil Engineering, University of Sydney

Working Papers from University of Minnesota: Nexus Research Group

Abstract: This study presents a stochastic delay model that treats signal-free intersections as systems of servers where the probability of conflict between vehicles determines delay. Rather than relying on predetermined major-minor hierarchies, the model builds on interaction between any two approaching vehicles attempting to occupy the same conflict zone simultaneously. This conflict-probability framework applies across many traffic scenarios, from traditional unsignalized multi-modal intersections, merging sections, and roundabouts to signal-free intersections for autonomous vehicles (AVs). The model employs queuing theory formulations where service time depends on conflict probability and clearance time for conflict zones. The model extends to multi-movement intersections through dependent and independent conflict zone networks and accommodates time-varying demand through dynamic parameter adaptation. Theoretical analysis reveals that equal inflows maximize delays due to peak conflict probabilities. Validation using real-world trajectory datasets demonstrates improvements over Highway Capacity Manual and Austroads methods across diverse scenarios. Furthermore, the proposed delay model achieves mean absolute errors of 4.6 to 10.9 s using simulation of signal-free intersections for AVs under first-come first-served and communication-free distributed control algorithm protocols.

Keywords: Signal-free junction; stochastic modeling; probability of conflict; autonomous vehicles; conflict networks; queue theory (search for similar items in EconPapers)
JEL-codes: R40 (search for similar items in EconPapers)
Date: 2026
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Published in Transportation Research Part C 191 105813

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https://doi.org/10.1016/j.trc.2026.105813 Published version landing page, 2026 (text/html)

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Persistent link: https://EconPapers.repec.org/RePEc:nex:wpaper:paper-2026-18

DOI: 10.1016/j.trc.2026.105813

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