Surface skid resistance

Skid resistance expresses how well a surface prevents tires or footwear from slipping, especially when wet and during braking, accelerating, or changing direction. In technical data sheets, it is indicated by values such as PTV (a measured value on a finished surface) and classification labels such as GS. However, the number alone is not enough. What matters is how and when it was measured and what application it is intended for.

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What is PTV

PTV (Pendulum Test Value) is a value measured by a pendulum tester (skid resistance tester) according to ČSN EN 13036-4. A rubber slider on the pendulum passes over a wetted surface, and the device measures the energy loss caused by friction. The higher the value, the greater the skid resistance of the surface during the test.

Watch out for a common mix-up: PSV (Polished Stone Value) is a property of aggregates (ČSN EN 1097-8), not the finished surface. The two abbreviations are not interchangeable.

When comparing PTV values, always check:

• what surface was measured (laboratory sample or finished work),
• when it was measured (new surface, or after traffic load or polishing),
• under what conditions (temperature, humidity, corrections).

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What GS means

GS is a classification designation for anti-skid properties. For WeTraffic systems 491 and 492 it is stated as GS 3.

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WeTraffic values

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Why a "rough surface" is not enough

Anti-skid performance depends on two texture properties:

• microtexture (the roughness of individual filler grains) ensures grip on both dry and wet surfaces,
• macrotexture (the overall surface structure) allows water to drain from the tire contact patch.

In WeTraffic, the structure is created by mineral filler, and for high-load systems, additionally by hard bauxite filler, which is more resistant to polishing. It is important to consider not only the initial value, but also its retention over time. Softer filler becomes smooth with use, and skid resistance decreases.

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When and why skid resistance matters

It is most important in areas where drivers need to react quickly:

• sharp curves and descents,
• approaches to pedestrian crossings,
• intersections, on-ramps and off-ramps,
• areas with frequent braking,
• wet and winter conditions.

Here, the surface affects braking distance and vehicle stability. It is one of the measures, not the only one. It does not replace addressing the root causes (speed, alignment, visibility).

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A higher PTV does not always mean a better choice

The requirement must match the location. For a sidewalk or bike path comfort, clarity, and abrasion resistance are decisive. For a heavily trafficked road, along with skid resistance, mechanical durability and long service lifeare also key. Assess the following simultaneously:

• type and intensity of traffic, vehicle speed,
• frequency of braking and changes in direction,
• climatic conditions and winter maintenance,
• condition of the sub-base,
• required service life.

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How to apply the values in practice

1. Determine the target value for the given location according to technical specifications and the designer's proposal.
2. Require documentation via a report (standard, conditions, laboratory).
3. Schedule a control measurement after application and, if applicable, after a certain period of operation.
4. Do not compare values from different methods (pendulum vs. friction coefficient measurement using other equipment) without conversion.

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Frequently asked questions

What is PTV for safety surfaces?‍

PTV (Pendulum Test Value) is a measure of skid resistance determined using a pendulum tester on a wet surface in accordance with ČSN EN 13036-4. For WeTraffic , PTV > 45 (491) and PTV > 65 (492).

Is a higher PTV always better?‍

No. A higher value indicates better skid resistance for that specific test, but the suitability of a surface also depends on the type of traffic, durability, service life, and testing conditions.

What does GS 3 mean?‍

GS is a skid resistance classification; both WeTraffic 491 and 492 are rated GS 3. 

What is the difference between PTV and PSV?‍

PTV is measured on a finished surface using a pendulum tester. PSV is a property of the aggregate after polishing.

Why is skid resistance important in the rain?

‍Water reduces tire contact with the surface and increases braking distance. A surface with appropriate micro- and macro-texture drains water from the contact area and maintains grip.

Which WeTraffic system has the highest skid resistance?‍

WeTraffic 492 (PTV > 65). It is designed for high-traffic areas. WeTraffic 491 (PTV > 45) is intended for pedestrians, cyclists, and slow-moving traffic.