Proposal to clarify UN R171 on Driver Control Assistance Systems (DCAS). The modifications include clarifications to definitions, adding “Highway-like road” definition; clarifications to system boundary detection, manoeuvre initiation, and driver disengagement requirements; amendments permitting withholding of hands-on requests on highway-like roads up to 130 km/h; clarifications on Risk Mitigation Function terminology; amendments allowing alternative strategies for lower-speed lane changes; addition of operational phase safety management processes; and clarifications on testing requirements and non-rule-based algorithm repeatability.

Consolidated version based on WP.29/2025/7 as amended by WP.29-195-05, WP.29/2025/144, GRVA-24-18, and GRVA-24-19. See GRVA/2026/18 for the proposed amendments.

Proposal to delete the draft “Reserved” paragraph 5.3.7.2.4.3. in GRVA/2026/18. Reserving paragraph 5.3.7.2.4.3. in the 01 series would mean that the subsequent paragraphs would be out of line with the numbering in the 02 series, making future amendments to UN R171 unnecessarily challenging.

Proposal to amend the original version (GRVA/2026/15), insert para. 5.3.7.2.1.13. to require the manufacturer to describe in the safety concept the system behaviour in case the driver is detected to be disengaged during a manoeuvre; amend the original version and the 01 series (GRVA/2026/15 and GRVA/2026/17), amend para. 3.5.1. of Annex 3 to require the manufacturer to demonstrate to the Type Approval Authority at least every three years that the safety management system continues to comply with requirements; amend the 01 and 02 series (GRVA/2026/17 and WP.29/2026/86), amend para. 2.3.2. of Appendix 2 of Annex 3; amend the 02 series (WP.29/2026/86), amend para. 4.2.5.2.19.2.1. of Annex 4; and amend the original version, 01 series and 02 series (GRVA/2026/15, GRVA/2026/17 and WP.29/2026/86), amend para. 4.2.5.2.14.1.2. of Annex 4 and para. 4.2.5.2.14.2.1. of Annex 4.

Proposal to:

• Amend Introduction para. 17 to clarify DCAS development based on current technology and data
• Amend para. 2.11 to delete “the” before “travel”
• Insert new para. 2.28.1. defining “Highway-like road” with characteristics including at least two lanes, designated speed limit of at least 80 km/h, physical separation dividing opposite traffic, and absence of at-grade pedestrian crossings, rail crossings, or road intersections
• Amend para. 5.3.5.1 to specify system shall leave active mode with exception of driver unavailability response
• Amend para. 5.3.7.1.4 to delete “the” before “front tyre”
• Amend para. 5.3.7.2.1.1 to change “detected” to “deemed” and specify disengagement duration of more than 2s
• Insert new para. 5.3.7.2.1.13 requiring manufacturer to describe system behaviour if driver detected disengaged during manoeuvre
• Amend para. 5.3.7.2.3.1 to delete requirements reference and require sufficient time for driver confirmation
• Amend para. 5.3.7.2.5.3.1 to add “or highway-like road” to highway operation requirements
• Delete para. 5.3.7.2.4.3 and renumber paras. 5.3.7.2.4.4 to 5.3.7.2.4.11 as 5.3.7.2.4.3 to 5.3.7.2.4.10
• Amend para. 5.3.7.3.1 to reference systems driver unavailability response and RMF requirements of 04 series UN R79
• Amend para. 5.3.7.3.3 to specify system capable of lane changes during driver unavailability response in compliance with RMF requirements
• Amend para. 5.5.4.2.2.3 to renumber and require warning strategies prioritize simultaneously activated emergency assistance systems
• Amend paras. 5.5.4.2.5.2 and 5.5.4.2.5.2.1 to specify visual disengagement criteria, dashboard consideration limited to 3 seconds, and visual re-engagement duration of at least 200 milliseconds
• Amend para. 5.5.4.2.6.5 to allow HOR withholding on highway-like roads at speeds up to 130 km/h and require verification of road characteristics for at least 500 m or 30 seconds, demonstration of safe cyclist operation, and HOR at least 7s before end of highway-like road
• Amend paras. 5.5.4.2.7 and 5.5.4.2.7.1 to add assessment of gaze direction changes and insert new para. 5.5.4.2.7.1
• Amend para. 6.2.4.1 to permit deviation from assessment at speeds up to 60 km/h with manufacturer explanation to Type Approval Authority
• Amend para. 14.2 to change “definitely” to “definitively”
• Amend Annex 1 to add para. 6.4.1 for system capability of withholding HORs on highway-like roads
• Delete Annex 3 paras. 2.15 and 2.16 defining “Highway” and “Non-Highway”
• Amend Annex 3 para. 3.1.1 to change “definitely” to “definitively”
• Renumber Annex 3 para. 3.5.7 to 3.4.5 and amend to require system information strategy