Protocol for the REVELIO test-track pilot study: A randomised, controlled, single-centre trial in healthy recreational cannabis users investigating real-time in-vehicle detection of cannabis-impaired driving.

Deuber R.; Bechny M.; Heck C.; Brügger J.; Pfäffli M.; Jovanova M.; Fleisch E.; Wortmann F.; Weinmann W. · PloS one · 2026

**Background & Methods** This is a randomised, controlled, single-centre pilot study conducted on a closed test track enrolling 45 healthy recreational cannabis users to assess the feasibility of developing a multimodal in-vehicle detection system for cannabis-impaired driving. Participants are randomised to either an intervention group receiving controlled cannabis or a reference control group, with all participants completing baseline and three subsequent standardized 50-minute driving sessions over approximately six hours, alongside biological sampling and pre-driving assessments. **Key Findings** This protocol describes a planned study and does not report findings, as data collection and analysis remain pending. The study aims to generate standardized reference data on temporal dynamics of cannabis-related driving impairment using machine-learning models integrating vehicle dynamics, driver monitoring, physiological signals, and biological THC concentrations. Secondary analyses will examine associations between functional driving performance measures and biological THC levels to inform real-time detection algorithms. **Dosage & Administration** A single controlled inhalative cannabis dose of 0.67 mg THC per kilogram of body weight was administered to the intervention group via inhalation. The reference control group received no cannabis. All participants underwent identical driving and assessment protocols regardless of allocation. **Safety & Adverse Effects** Not reported. This protocol document does not describe adverse events, as the study remains in the planning phase. Safety monitoring procedures and adverse event reporting protocols are not detailed in the abstract provided. **Evidence Quality** This is a methodological protocol paper describing a planned pilot study rather than a completed trial with reported outcomes. As a prospective protocol, the evidence quality cannot yet be assessed. Study limitations include the single-centre design on a controlled test track (limiting real-world generalizability), open-label design (potential bias), and exclusive recruitment of healthy recreational users (limiting applicability to diverse populations). The relatively small sample size (n=45) reflects its pilot nature. Strengths include standardized procedures, multimodal data collection, and rigorous biological sampling. Registration at ClinicalTrials.gov (NCT07401628) enhances transparency. Results from this pilot will be essential for determining feasibility and informing future larger-scale validation studies of in-vehicle cannabis impairment detection systems.

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