Standards revisions rarely make interesting reading, but occasionally one changes the ground rules in a way that reaches the supply chain. China’s GB/T 16311-2024, Quality Requirements and Test Methods for Road Traffic Markings, is one of those. It took effect on 1 March 2025, replacing both GB/T 16311-2009 and GB/T 21383-2008, and it alters what gets measured, when it gets measured, and what counts as passing.
If you buy or supply glass beads for markings, four changes matter.
Change 1: The finished marking now gets tested for bead content
This is the most consequential change for anyone in the bead business.
The 2009 edition concerned itself largely with the coating material. The 2024 edition adds quality requirements, sampling methods and test methods for glass bead content within thermoplastic coatings, total organic content, and heavy metal content of the finished thermoplastic marking.
Read that again in supply-chain terms. It is no longer sufficient for the bead delivered to the site to pass its own test. The laid line is now subject to sampling, and its internal bead content and roundness can be measured. If the beads were good on arrival but ended up buried, blown off, or inadequately proportioned in the mix, the defect surfaces at acceptance — and the acceptance test is conducted on the completed work.
For this to work, testing has to happen after application. Under GB/T 16311-2024, the “initial” retroreflective luminance coefficient is defined as a measurement taken between 48 hours and 30 days after striping is completed. The old standard’s definition of an initial state as the first 14 days is gone.
There is a practical consequence here for buyers: keep your bead documentation. If the finished line is sampled, the batch report is what supports the conversation about whether the shortfall originated with the material or the application.
Change 2: Retroreflectivity classes, stated as numbers
The 2024 edition sets initial retroreflective luminance coefficient requirements for Type I reflective markings under dry conditions, and grades them:
| Class | White (mcd·m⁻²·lx⁻¹) | Yellow (mcd·m⁻²·lx⁻¹) |
|---|---|---|
| Class I (standard) | 150 to <250 | 100 to <125 |
| Class II (medium) | 250 to <350 | 125 to <150 |
| Class III (high) | ≥350 | 150 to <175 |
| Class IV (ultra-high) | ≥450 | ≥175 |
The absolute floor for a Type I marking is therefore 150 mcd·m⁻²·lx⁻¹ for white and 100 mcd·m⁻²·lx⁻¹ for yellow in dry conditions. The standard also introduces requirements for Type II markings, and defines measurement for one wet-night marking category.
Two structural changes accompany the table. First, the old “during normal service life” requirement — previously white 80 and yellow 50 — has been removed; in-service values are now handled by a separate highway quality standard. Second, the standard now covers four dry marking classes plus one wet-night class, which means a specification should state which class it is targeting rather than just quoting a single number.
Design practice in China has largely settled on specifying Class III (≥350 mcd for white) for new reflective markings, or referencing the highway quality assessment standard’s in-service thresholds.
Change 3: Anti-skid performance becomes universal
The 2024 edition adds anti-skid requirements for all marking types, not just specialty anti-skid products. Initial skid resistance must be at least 45 BPN for standard anti-skid and at least 55 BPN for high anti-skid. In-service or warranty-period skid resistance is handled by the highway quality assessment standard.
Why this matters to the bead supply chain: it explains the push toward profiled beads in the market — beads designed to sit partially embedded and form a raised, textured surface that improves grip as well as reflection. When a project has to satisfy both a retroreflectivity class and a BPN threshold, the bead specification is one of the places where a solution is found.
Change 4: Material colour is separated from retroreflective colour
The 2024 edition introduces distinct definitions and chromaticity coordinate ranges for two things that were previously conflated:
- Marking material colour — the colour of the marking surface as applied, after the drop-on beads have been scattered.
- Retroreflective colour — the colour the marking appears to a driver when it reflects light at night.
The standard also expands the range of permitted marking colours, adding grey, green, purple, brown and black alongside the traditional white and yellow.
The practical impact lands hardest on yellow markings. Historically, a common way to raise a yellow marking’s retroreflective reading was to add more titanium dioxide, which brightens the coating generally. Under the new scheme, material colour and retroreflective colour each have their own coordinate envelopes, so piling in white pigment to lift the reading is no longer a legitimate route. The expected result, as Chinese industry commentary puts it, is a reduction in yellow markings that retroreflect as white — a phenomenon that has long confused drivers at night.
The bead standard these depend on
GB/T 16311-2024 operates alongside GB/T 24722-2020, which governs the beads themselves. The requirements a buyer should be able to obtain from a supplier under that standard include:
| Property | Requirement |
|---|---|
| Appearance | Colourless, white or pale yellow; clean; transparent spherical bodies under microscope; no obvious bubbles or inclusions |
| Roundness (low-RI, Type 1 & 2) | ≥80%; and ≥70% for Type 1 beads in the 850–600 µm band |
| Defective bead percentage (medium/high-RI) | ≤20% |
| Density | 2.4 – 4.6 g/cm³ |
| Water resistance | Type 1 & 2: 0.01 mol/L HCl neutralised ≤10 mL; Type 3: ≤15 mL |
| Magnetic particle content | ≤0.1% |
| Moisture-proof coating | Coated beads must pass through a funnel without stalling |
| Lead | ≤200 mg/kg |
| Arsenic | ≤200 mg/kg |
| Antimony | ≤200 mg/kg |
The heavy metal limits are new in the 2020 edition, and they are increasingly requested by buyers in Europe and the Middle East as part of routine material due diligence. A supplier who can produce those figures without a chase is easier to work with.
What a buyer outside China should take from this
Even if your project is not governed by Chinese standards, three things are worth noting.
One: finished-marking testing is spreading. The logic of measuring internal bead content on the laid line rather than just at the factory gate is sound, and it is the direction other jurisdictions have moved or are moving. If your supplier’s quality system only covers pre-shipment testing, there is a gap between their evidence and your risk.
Two: anti-skid and retroreflectivity are now requirements on the same product. Where both apply, the bead specification has to serve both. That generally means a conversation about profiled or coated beads rather than a commodity grade.
Three: colour specifications are tightening. The separation of material colour from retroreflective colour in the Chinese standard reflects a real-world problem — yellow lines that read white at night. If your market has any concern about marking colour fidelity in wet or night conditions, raising RI class and specifying a coated bead is the lever, not adding pigment.
Documentation to request
Given all of the above, a bead data pack worth asking for now includes: RI class and test method; roundness or defect percentage; sieve analysis against the applicable standard’s table; density; water resistance; magnetic particle content; and heavy metal content (Pb, As, Sb). For projects with an anti-skid requirement, add whatever coating or profiling specification applies.
We can supply beads tested against GB/T 24722-2020 with the sieve tables aligned to AASHTO M247 and EN 1423 as well, so the same batch satisfies more than one market’s paperwork. If you are updating a specification and want to see how the Chinese table maps to the one your project uses, send it over — we will lay them side by side.
Related reading
- AASHTO vs EN vs BS — bead standards
- Standards (short) — bead standards
- Spec Checklist — road marking selection
- Drop-On vs Premix (short) — road marking selection