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IS 15684:2018 is the Indian Standard (BIS) for retro-reflective sheeting for road signs - specification. This standard specifies the requirements for micro-prismatic retro-reflective sheeting used for traffic signs, delineators, and other traffic control devices. It classifies sheeting into high-performance types (IV, IX, XI) and details the photometric, colorimetric, physical, and durability properties to ensure nighttime visibility and longevity.
Specifies requirements for retro-reflective sheeting materials used for the fabrication of permanent and temporary road signs to ensure visibility.
! This standard is aligned with modern ASTM D4956 types, focusing on high-performance micro-prismatic sheetings (Type IV, IX, XI) and phasing out older, less efficient glass-bead sheetings (like Type I).
! The choice between Type IV, IX, or XI depends on the road category and required conspicuity, as specified by the client or in IRC:67. Higher types offer better angularity and brightness but at a higher cost.
! Ensure the sheeting is applied according to the manufacturer's instructions on a properly prepared substrate (e.g., aluminum composite panel) to achieve the specified 10-year durability.
Standard Specification for Retroreflective Sheeting for Traffic Control
Directly specifies classification, performance, and durability requirements for retroreflective sheeting.
AS/NZS 1906.1:2017Standards Australia / Standards New Zealand, Australia/New Zealand
HighCurrent
Retroreflective materials and devices for road traffic control purposes, Part 1: Retroreflective materials
Covers performance requirements and classification for retroreflective sheeting used on traffic signs.
EN 12899-1:2007European Committee for Standardization (CEN), Europe
MediumCurrent
Fixed, vertical road traffic signs - Part 1: Fixed signs
Specifies the entire sign assembly, with retroreflective sheeting performance as a major sub-component.
BS 8408:2005British Standards Institution (BSI), UK
MediumWithdrawn
Road traffic signs. Testing and performance of microprismatic retroreflective sheeting materials. Specification
Focused specifically on microprismatic sheeting, a subset of materials covered by IS 15684.
Key Differences
≠IS 15684 uses a material-and-performance 'Type' system (I to XI) heavily based on ASTM D4956, whereas EN 12899-1 uses performance-based 'Classes' (RA1, RA2, R3B) that are not tied to material construction.
≠The specific chromaticity coordinates (color boxes) defining acceptable colors like white, yellow, and red differ slightly between IS 15684 and ASTM D4956, leading to minor variations in acceptable color shades.
≠IS 15684 specifies a more stringent flexibility test for certain sheeting types, requiring bending around a mandrel at -7°C without cracking, while the corresponding ASTM D4956 test is performed at ambient temperature (23°C).
≠Durability requirements for equivalent sheeting types can differ. For instance, ASTM D4956 requires Type I sheeting to be weathered for 2 years, whereas IS 15684 specifies 1 year of weathering for the same type to meet its retained retroreflectivity criteria.
Key Similarities
≈All standards use the Coefficient of Retroreflection (RA), measured in candelas per lux per square meter (cd/lx/m²), as the fundamental performance metric for brightness.
≈IS 15684 explicitly references and adopts numerous ASTM test methods for physical and durability properties like adhesion, impact resistance, and shrinkage, creating a strong methodological alignment with ASTM D4956.
≈All standards classify sheeting into multiple performance tiers or classes, allowing engineers to specify materials appropriate for different road conditions, sign importance, and service life expectations.
≈Requirements for durability are central to all standards, mandating tests for outdoor weathering (or accelerated artificial weathering) and setting minimum retained retroreflectivity and color fastness levels after exposure.
Parameter Comparison
Parameter
IS Value
International
Source
Min. RA for Type IV (White) at 0.2°/-4°
360 cd/lx/m²
360 cd/lx/m²
ASTM D4956-23
Min. RA for Type I (White) at 0.2°/-4°
70 cd/lx/m²
70 cd/lx/m²
ASTM D4956-23
Flexibility Test Temperature
-7°C (for certain types)
23 ± 2°C (ambient)
ASTM D4956-23
Retained RA after weathering (Type I Sheeting)
≥50% of initial minimum after 1 year
≥50% of initial minimum after 2 years
ASTM D4956-23
Shrinkage (Max)
0.8 mm after 24h at 70°C
0.8 mm after 24h at 71°C
ASTM D4956-23
Chromaticity Coordinates (White, Corner 1)
x=0.300, y=0.285
x=0.303, y=0.300
ASTM D4956-23
Impact Resistance
1.13 N·m (10 in-lb)
1.13 N·m (10 in-lb)
ASTM D4956-23
⚠ Verify details from original standards before use
What are the main types of sheeting covered in IS 15684?+
It covers three types of micro-prismatic sheeting: Type IV (High-Intensity Prismatic), Type IX (Very High-Intensity Prismatic), and Type XI (Superior Intensity Prismatic).
What is the specified service life for sheeting under this code?+
The standard specifies a minimum 10-year durability for all types (IV, IX, XI) when properly processed and applied (Clause 6.1.1).
Which code tells me which type of sheeting to use for a highway sign?+
IRC:67 (Code of Practice for Road Signs) specifies the design and application of signs, which in turn dictates the minimum required sheeting type based on the road category and sign type.
Does this standard include requirements for fluorescent colors?+
Yes, Annex C and related tables provide colorimetric and photometric requirements for fluorescent yellow-green, fluorescent yellow, and fluorescent orange sheeting.