SLR-76 session documents are available on the SLR website. Actions include: correcting errors in UN R150 for submission to GRE-94; preparing Stage 2/Step 2 baseline documents for UN R48, R53, R74, and R86; finalizing simplification of paragraphs 6.×.4 and 6.×.5; discussing apparent surface methodology; approving technological neutrality amendments to UN R48 and R149; collecting literature on rear direction indicator visibility; and reviewing harmonization requirements. SLR-77 meeting scheduled April 15-17, 2026 in Brussels.

OICA presents research findings on direction indicator perceptibility when stop lamps activate simultaneously. Key findings indicate that spatial separation between functions, increased direction indicator intensity, and relative signal dominance improve perception. Research shows stop lamp luminance can reduce direction indicator recognition, particularly in near-field viewing. OICA concludes that minimum size requirements proposed in the German proposal exceed available evidence and may create unintended consequences without demonstrated safety benefits.

The document analyzes separating direction indicators and stop lamps. It examines how drivers recognize lighting functions through visual perception and notes that irregular lamp shapes increase reaction time. The document states that “apparent surface”, currently defined only through manufacturer drawings, lacks perceptual grounding because it ignores luminance distribution and edge contrast. It recommends minimum lamp sizes and distances based on visual acuity, minimum luminance requirements, and a 3:1 luminance contrast between functions when spatially merged in one lamp.

A literature review on direction indicator visibility presents research on vehicle lighting design, visibility, and signalling. Sources include studies on overlapping and interlocking of lights, and dynamic evaluation of automobile rear lighting configurations.

This document addresses rear direction-indicator lamps mounted at low positions on vehicles. Republic of Korea reports increased public petitions and media articles regarding visibility and recognition concerns, particularly in congested traffic and for vehicles with higher driver seating positions like SUVs. UN Regulation No. 48 specifies direction-indicator lamp height requirements: not less than 350 mm and not more than 1,500 mm, or up to 2,100 mm under certain structural conditions. The presentation seeks feedback on similar issues from other countries and manufacturers.

Baseline document for amending UN R74 (based on WP.29/2024/91, SLR-71-07, SLR-71-7, SLR-66-01, and SLR-73-07). Key changes include: simplifying definitions; using “type-approved” and “type-approval” with hyphens per UN R48; replacing “vehicle type (moped)” with “type of vehicles of category L₁”; adding hyphenation to “direction-indicator lamp”; deleting “above” from paragraph references; clarifying UN R48 series; removing “to this Regulation” after Annex references; applying scientific notation for lumens; including electric vehicles; revising individual and general provisions; correcting signal lamp category errors; and using category symbols instead of lamp function names.

Draft amendments to UN R53 (based on SLR-71-07, SLR-71-7, SLR-66-01, SLR-73-07, SLR-75-05, and WP.29/2024/30) updates the baseline document for the 05 series of amendments. Key changes include: simplification of definitions and general specifications; consolidation of individual specifications; addition of EV inclusion and failure provisions; editorial harmonization with UN R48 baseline regarding hyphenation, terminology, and formatting; replacement of “visual failure tell-tale” with “tell-tale indicating failure” and “rear-end collision alert signal” with RECAS; standardization of vehicle category references; adoption of scientific notation with lumens; simplification of paragraphs 6.4 and 6; and revision of the transitional provisions.

Based on SLR-76-03-Rev1 for R48 and tentatively applying WP.29/2024/76, IMMA presents transitional provisions for UN R53. The document outlines provisions applicable to all amendment series, including that Contracting Parties may grant type-approvals according to any preceding series and shall continue granting extensions of existing approvals. For the 05 series of amendments, specific dates establish when Contracting Parties shall accept or refuse type-approvals, with exceptions for equipment, parts, and unaffected vehicle systems.

The agenda includes corrections to UN R150-01, baseline documents for UN R53, R74, R86, and R48, simplification of paragraphs 6.×.4 and 6.×.5, transitional provisions, harmonisation of requirements, apparent surface considerations, and direction indicator visibility improvements. The next meetings are scheduled for June and December 2026, with a potential September 2026 session in Tokyo.

UN R48 baseline text for a 10 series of amendments proposes uniform provisions for vehicle lighting and light-signalling device installation approval. The document consolidates modifications agreed at working group session through dated amendment documents and resolutions. Pending issues include determining “[any] subsequent series” terminology for frozen regulations, renumbering and cross-checking paragraphs, addressing apparent surface visibility, improving daytime running lamp visibility against stop lamps, resolving “prohibited if not allowed” language, and numbering all figures with titles. Editorial polishing includes standardizing hyphenated terminology (“driving-beam,” “passing-beam,” “retro-reflector,” “direction-indicator lamp”), applying consistent UN Regulation references, replacing “communication sheet” with “communication form,” assigning table and figure numbers consistent with similar regulations, and correcting percentage notation to “per cent.”

GTB proposes simplifying UN R48 by developing a single CAD-based method to determine apparent surface at early design stages. The proposal deletes the “light-emitting surface” definition and establishes “apparent surface” as the orthogonal projection of visible light-emitting surfaces in a specified observation direction. Amendments include revised definitions for lens, textured outer lens, illuminating surface, and apparent surface, with modified requirements for single lamps with multiple distinct parts. Distance requirements between adjacent parts are adjusted to 75mm or 200mm depending on lamp type.

The 79th SLR Informal Working Group Meeting will be held 7–11 September 2026 at JASIC Meeting Room, 7th Floor, Zennihon Truck Sogo Kaikan, 3-2-5 Yotsuya, Shinjuku-ku, Tokyo 160-0004, Japan. The meeting schedule, venue, and other details are expected to be finalized in the later half of May. The document provides hotel accommodation options, airport information, and local transit guidance for attendees.