Performance, Well Beyond 12 Million Wheel Passes

Clear, long-term visibility of road markings is essential. Only markings that drivers can reliably see can elevate road safety. Many systems deliver strong initial values, but very few continue to perform under heavy traffic over extended periods. That dependable visibility is measured not just in months, but in millions of wheel passes...

12 Million Wheel Passes: A New Benchmark

SWARCO set out to quantify this precisely. At the Federal Highway Research Institute in Germany (BASt), a SWARCO marking system underwent a rigorous endurance test on BASt’s rotary traffic simulator (Rundlaufprüfanlage, RPA). Specifically, SWARCOPLAST G601—an MMA-based cold plastic system combined with SWARCO SOLIDPLUS reflective glass beads—was assessed for visibility, pushing far beyond the currently highest requirement of 4 million simulated wheel passes. In fact, the test tripled that threshold.

The result: Even after 12 million simulated wheel passes, retroreflectivity values remained clearly above the thresholds for the highest classes of EN 1436—for both agglomerate markings and full lines. This puts the MMA-based system in a class of its own. As Mario Nöllge, Managing Director at SWARCO’s Diez site, emphasizes: “No other marking system of this type has previously achieved such outstanding long-term performance. The key is the premix glass beads, which—used for the first time in a cold-plastic full-line system—deliver excellent retroreflection over such an extended period.” Detailed measurements for a 3 mm full-line marking show:



Initial4 million12 million
RL [mcd * m² * lx^-1] 909547354
RW [mcd * m² * lx^-1] 14849147


Proven Long-Term Performance

Why do the values remain so high? In short, because the marking material and micro glass beads are engineered to work together as a high-performance system. SWARCOPLAST G601, with its high whiteness, provides a solid foundation. The drop-on beads remain securely embedded in the MMA cold plastic for a long time. Controlled, gentle wear gradually exposes the premix beads within the material—without damaging them. The result is sustained retroreflection, even under heavy traffic and winter maintenance.

Mario Nöllge underscores the importance of product quality: “Achieving these retroreflectivity levels after so many wheel passes requires premium raw materials—from the methacrylate resin and titanium dioxide pigment to our SWARCO SOLIDPLUS glass beads.”

Due to their specially engineered glass composition, SWARCO SOLIDPLUS reflective beads also deliver exceptional durability. Numerous field applications have shown that these premium beads withstand mechanical loads far better than standard beads. In combination with other high-grade system components (MMA binder, titanium dioxide, etc.), their back-reflection performance can be maintained at a high level over the long term.

Why Consistent Visibility Matters

Safety gains come from consistency, not just peak values—and that is precisely what the measurements confirm. Standards and guidelines—such as the Manual on Uniform Traffic Control Devices (MUTCD) in the United States—define minimum values, for example an RL of 50 or 100
mcd⋅m^(2)⋅lx^(−1) depending on posted speed limits. Similarly, EN 1436 provides a clear performance framework for road markings.

Accordingly, road authorities seek high-quality markings that reliably meet these levels under sustained loads and over long periods. That’s why valid data is crucial: SWARCOPLAST G601 markings demonstrate reserves even after massive mechanical stress from millions of wheel passes. For road authorities and road operators, this translates into longer maintenance intervals, predictable life-cycle costs, fewer work zones, and reduced material usage—without compromising safety.

What’s Next?

The results to date clearly show that markings made with SWARCOPLAST G601 and SWARCO SOLIDPLUS glass bead technology remain visible for a long time. For SWARCO Road Marking Systems, this is not the finish line. Where others are satisfied, we want to learn more, test further, and keep improving. We are therefore continuing the investigations systematically—even under extreme conditions and well beyond 12 million wheel passes. Real road safety is built not on assumptions, but on knowledge, precision, and continuous innovation.

FAQ

At the Federal Highway Research Institute in Germany, long-term traffic loading is simulated under controlled conditions. Test wheels repeatedly traverse the marking to replicate mechanical wear. While the highest current class requires only 4 million passes, stable RL and RW values after 12 million demonstrate that visibility is preserved deep into the service life. The results provide robust numbers, complement field trials, and support maintenance planning. 

Reflective glass beads return headlight beams back to the driver via retroreflection. Beads with a higher refractive index (1.6–1.7) and optimized embedment depth maximize this effect. Performance is measured as RL (dry) and RW (wet) in 
mcd⋅m^2⋅lx^−1. High, stable values enhance lane perception, curve guidance, and forward visibility at junctions over extended periods—helping reduce steering and braking errors, especially at night. 

In the rain, road markings and their beads can be covered under a film of water, preventing light from returning to the driver. Textured marking surfaces create micro-channels that drain water and keep the retroreflective layer at the surface. Larger bead sizes can also help maintain visibility in wet conditions. 

They balance mechanical durability and optical efficiency at a high level. This requires resilient materials, premium reflective glass beads, and tailored surface treatments for optimal bead embedment. Surface textures add drainage effects. With high-quality components, the difference shows over time: RL and RW remain above required thresholds longer, enabling extended maintenance cycles with consistently high traffic safety. 

These premium reflective beads use a specially engineered glass formulation that combines a high refractive index with outstanding robustness. This enables excellent retroreflectivity and reduces bead loss under heavy traffic—delivering a double benefit for long-term marking visibility.

Not necessarily. Strong initial RL and RW are important, but the real test is maintaining them under continuous traffic and weathering. Systems validated beyond standard requirements—with supporting data from lab and field—provide a more reliable basis for operational and maintenance decisions. 

Consistent visibility extends inspection and renewal intervals and reduces crash risk. Longer maintenance cycles mean fewer work zones, lower life-cycle costs, and reduced material consumption—improving both planning reliability and environmental performance.