When specifying a bridge or boardwalk, slip resistance is one of the few performance characteristics that can be quantified, compared and verified. Yet it’s also one of the most misunderstood.
Manufacturers often describe a walking surface as “anti-slip”, but that tells you very little about how it has been tested or how it is likely to perform in situ. For landscape architects, engineers and local authorities, the more useful question is: what is the Pendulum Test Value (PTV), and how has it been achieved?
Why the Pendulum Test Matters
The Pendulum Test is the recognised method for measuring pedestrian slip resistance in the UK. It assesses the friction between a standard rubber slider and the walking surface to produce a Pendulum Test Value (PTV).
The UK Slip Resistance Group classifies the results as:
● PTV below 25 – High slip potential
● PTV between 25 and 35 – Moderate slip potential
● PTV above 35 – Low slip potential.
For a bridge or boardwalk that will spend its life exposed to rain, standing water, leaf litter and mud, the wet PTV is the figure that really matters.
Understanding Polydeck’s PTV Results
Polydeck’s castellated POLYplank™ achieves a wet Pendulum Test Value of 92. The timber-effect finish achieves a wet PTV of 52. Both comfortably exceed the threshold for a low slip potential, but the castellated profile delivers exceptional performance for structures where maximum grip is required.
Even more importantly, those figures are not the result of an applied coating that will wear over time.
Instead, the anti-slip surface is created during manufacture using a near-diamond-hard aluminium oxide aggregate that becomes an integral part of the GRP plank. Combined with the
castellated profile, which encourages water to drain from the walking surface, this creates a durable surface that is designed to retain its slip resistance throughout the life of the structure.
That’s an important distinction when specifying bridges and boardwalks with a design life measured in decades rather than years.
A bridge in a saltmarsh, country park or woodland needs to provide the same confidence after years of exposure to the elements, with minimal maintenance and minimal disruption to the surrounding environment, not just when it has been first installed.
Combined with thermoset GRP construction that won’t rot, corrode or distort, and a design life in excess of 75 years, the result is a bridge or boardwalk system designed to deliver consistent performance throughout its service life.
Specifying Against Timber
Timber remains a popular choice for bridges and boardwalks, particularly in environmentally sensitive locations where a natural look is required. However, when specifying for long-term performance, it’s important to consider how the walking surface will change over time, and what this means for slip resistance.
As timber weathers, its surface gradually becomes smoother through wear and is increasingly susceptible to moisture, algae and organic growth. Even with regular maintenance, these factors can affect grip and may require cleaning, anti-slip strips or replacement boards to maintain safe access.
Polydeck’s castellated POLYplank™ is manufactured with a near-diamond-hard aluminium oxide aggregate integrated into the GRP surface, rather than relying on a treatment or coating applied afterwards. The result is a wet Pendulum Test Value (PTV) of 92, substantially above the UK Slip Resistance Group’s benchmark for a low slip potential.
This is particularly valuable for bridges and boardwalks installed in woodlands, wetlands and coastal environments, where exposure to rain, leaf litter and damp conditions is unavoidable. Rather than relying on ongoing interventions to maintain grip, Polydeck’s anti-slip surface is engineered into the plank itself, providing confidence that the structure will continue to perform throughout its design life.
Ultimately, a Pendulum Test Value is only useful if it reflects how a product will perform in the real world. By understanding what the figures mean, and how they’re achieved, specifiers can make informed comparisons between different bridge and boardwalk systems.
If you’re working on a project and would like to discuss slip resistance or find out more about Polydeck’s range of GRP bridges, boardwalks and structural planks, get in touch with our team.