Meeting report documenting discussions on proposed amendments to the driver drowsiness alert warning (DDAW) system regulation. Topics addressed include: clarification of warning acknowledgement and continued monitoring; mandatory microsleep detection as a distinct safety-critical event; expanded operating conditions for system effectiveness; interaction between DDAW and Driver Control Assistance Systems (DCAS); system performance under driver occlusions such as eyewear; drowsiness warning thresholds and advisory information; false negative event classification methodology; test participant selection and validation procedures; specificity and positive predictive value as performance metrics; and Observer Rated Drowsiness (ORD) as an alternative to KSS measurement. The IWG discussed these proposals to inform development of a 01 series of amendments to UN Regulation No. 182.

Summary of research findings from DDADWS meetings 8 and 9 concerning driver drowsiness detection and warning systems. Topics covered include fatigue contributing to 15–30% of road crashes, the safety-critical nature of KSS levels 8 and 9, distinguishing drowsiness from microsleep events, eye-closure behaviour as a practical detection tool with 2-second minimum duration criteria removing 85% of false positives while preserving 90% of true positives, KSS as a validation reference measure, testing environments including simulators and on-road conditions, system performance metrics, observable signs of drowsy driving including lane deviations and ocular indicators, participant demographics and state, ensuring valid drowsiness testing, warning effectiveness and escalation strategies, and evidence-based design factors for drowsiness warnings.

Presentation on maintaining effective drowsiness monitoring when Driver Control Assistance System (DCAS) is active. A DDAW system using indirect means cannot effectively assess driver drowsiness when the driver is not nominally required to steer, brake, or accelerate. Hands-on or eyes-on engagement does not establish alertness. Either the DDAW system or an alternate system should meet prescribed DDAW system performance while DCAS is active, with no gap in coverage or performance. UN R171 02 series amendments do not prescribe DDAW-equivalent performance criteria for drowsiness determination.

Proposal to develop a mandatory, testable microsleep detection and warning capability for the 01 series. Microsleep is a brief loss of consciousness indicated by 1–3 second eye closure that presents an immediate and significant road safety risk. The system should detect eye closure over time, use supporting cues such as neck droop or body slump to confirm events, and provide a dedicated and appropriately forceful warning strategy. Detection logic may use primary criteria such as >95% eye closure for >2.5 seconds or combined criteria such as >85% eye closure for >1.8 seconds plus neck droop or body slump. Testing pathways include controlled simulation with deliberate eye-closure events and fatigued-driver testing to observe genuine microsleep events.

Proposal to expand minimum operating conditions for driver drowsiness and attention warning systems to include roads with absent or significantly faded lane markings requiring road-edge detection capability, strong direct light directed towards driver-facing and road-facing sensors, and cabin temperature and humidity conditions prone to causing camera fogging. The proposal applies technology-neutral consolidated performance requirements rather than distinguishing between direct and indirect system means. Data from Australian and Great Britain road networks show that the majority of road fatalities occur in rural areas on roads often unmarked or with degraded markings, and road-edge detection is already technically available and demonstrated by vehicles tested under ANCAP protocols.

Presentation summarising proposal 5 on drowsiness warnings acknowledgement. The 00 series permits warnings to cascade and intensify until driver acknowledgement but does not clearly prescribe acceptable driver actions or subsequent system response. Acknowledgement does not remove drowsiness risk. Proposal seeks to define acceptable acknowledgement actions, require continuous monitoring after acknowledgement, and mandate renewed warnings when safety conditions persist or return within a maximum time-period. Microsleep warnings must not be muted through acknowledgement of drowsiness warnings.

Presentation on proposal 6 summarising enhancements to DDAW system test methodology. Proposes setting clearer requirements for participant selection, pre-conditioning, repeated testing of each participant, continuation of testing after the first true positive warning, and capture and treatment of near-crash events. Addresses existing limitations including narrow participant coverage, limited lighting conditions, testing that ends after the first true positive, and exclusion of false negatives during learning phases. Proposes mandatory methodology for representative evidence including minimum test runs per participant, broader demographic and physical characteristic representation, fatigued and rested participant preparation, near-crash event capture, and shorter learning periods. Notes the interconnectedness to other 01 series proposals including drowsiness threshold, false negative classification, operating conditions, and performance metrics.

Proposal to distinguish optional early information from mandatory warning thresholds by allowing optional soft information at Karolinska Sleepiness Scale (KSS) levels 6–7 and requiring mandatory hard warnings at KSS 8 or above. The proposal sets one mandatory threshold for warning classification and performance criteria, allowing visual advisory messages with limited audible tone at KSS 6–7 without driver acknowledgement required, and requiring clear visual indicators, audible warnings with minimum duration and volume, and haptic escalation at KSS 8 or above. Hard warnings would be subject to validation testing for sensitivity, specificity, and positive predictive value classification.

Proposal to record successive false negative events for each interval where the driver remains at or above Karolinska Sleepiness Scale (KSS) 8 and no warning is given, after a defined grace period of [X] minutes following the initial false negative. Currently, under the 00 series of UN R182, only one false negative is recorded per KSS transition, regardless of warning delay duration. The proposal introduces a time-based penalty to penalise delayed detection and make sensitivity metrics better reflect actual system performance.

Proposal to include specificity and positive predictive value (PPV) as complementary performance metrics in the 01 series alongside sensitivity. Specificity measures how well the system avoids warning non-drowsy drivers; PPV measures how often a warning corresponds to genuine drowsiness. Both metrics address the false-positive burden not adequately shown by the 00 series, which focuses on sensitivity alone. Separate criteria should be set for drowsiness monitoring and microsleep detection, developed together with revised test methodology rather than simply added to the existing methodology.

Proposal to:

• Add microsleep detection capability to DDAW systems,
• Require DDAW or equivalent monitoring when partial automation is active,
• Define broader driving conditions for effective operation including unmarked roads and direct lighting,
• Establish DDAW functionality under driver occlusions such as sunglasses,
• Set requirements for drowsiness warnings and acknowledgement by drivers,
• Enhance test methodology including continuation after first warning and demographic diversity,
• Establish mandatory drowsiness warning threshold at KSS level 8 with optional soft warnings at KSS levels 6–7,
• Introduce time-based penalties for delayed detection of drowsiness,
• Include specificity and positive predictive value as performance metrics.

Proposal to insert a definition of Observer Rating of Drowsiness (ORD) as a methodology for assessing driver drowsiness, amend paragraphs 5.5.2. and 5.5.2.1. to establish drowsiness warning thresholds using both the Karolinska Sleepiness Scale and ORD, amend Annex 4 to include ORD validation requirements including assessor training with minimum concordance rate of 0.70, rating procedures with at least 2 assessors, measurement intervals of 5 minutes or less, video quality standards, and calculation of final ratings as averages of assessors’ ratings, amend paragraph 6.3.1. to permit alternative measurement methods including sleep video analysis by at least 3 sleep experts, amend paragraph 6.3.2. to require evidence of validity and equivalence to KSS levels, delete former paragraph 6.3.2.1., amend paragraph 6.4.1. to permit complementary measurements, and amend paragraphs 7, 7.1., 7.2., and 8.1. to establish equivalence requirements between alternative measurements and KSS or ORD thresholds.

The agenda includes:

• DDAW system warnings and driver acknowledgement,
• microsleep detection requirements,
• system effectiveness under varied driving conditions and when DCAS is active,
• system functionality where driver occlusions occur,
• drowsiness thresholds for warnings,
• criteria for classifying false negatives,
• test methods,
• specificity and positive predictive value as performance metrics,
• observer-rated drowsiness,
• timing of future meetings.

Proposal to add Observer Rating of Drowsiness (ORD) as a primary drowsiness assessment method alongside the Karolinska Sleepiness Scale (KSS) for the Driver Drowsiness Alarm Warning (DDAW) system. The proposal modifies warning thresholds to reference ORD level [D4], updates validation testing requirements in Annex 4 to include ORD assessment procedures with specified assessor training and concordance rate standards, and establishes measurement intervals of 5 minutes or less. Japan is conducting a driving simulator study to validate appropriate ORD warning thresholds for submission after the October 2026 session.