The Pendulum Test Value is a single whole number that tells you how slip-resistant a surface is. It is the result of a pendulum test performed under BS EN 16165 (formerly BS 7976) and UKSRG Guidelines Issue 6, and it is the number every slip-related conversation in the UK eventually refers back to.
The Pendulum Test Value is a dimensionless number on a scale from 0 to 150. It represents the energy lost to friction as a rubber slider sweeps across the test surface over a 127 mm contact length. The greater the friction, the more energy absorbed, the less the pendulum arm continues to swing, and the higher the recorded PTV. A PTV of zero represents a theoretically frictionless surface. A PTV of 150 represents an extreme-grip surface.
In real-world UK pedestrian surfaces tested in the wet, PTV values cluster between 15 and 70. Virtually every commercial floor measurement you will encounter falls within this band.
This three-band classification was calibrated against real-world slip accident data by the Health and Safety Laboratory. The boundary at PTV 36 represents the value above which slip accident rates, on level pedestrian surfaces walked by healthy adults, fall to an acceptably low baseline.
The threshold is empirical, not arbitrary. HSE-commissioned research correlated measured PTVs with observed slip accident frequency on the same surfaces. The slip accident rate is sharply higher below PTV 36 and comparatively stable above it. The threshold was set at the lowest value at which the rate was considered tolerable for general pedestrian use.
The PTV 36 threshold assumes:
Where any of these assumptions don't hold — a sloped ramp, a care home with frail residents, an accessibility route for wheelchair users, a dark plant room — the PTV target is higher. HSE guidance provides gradient-adjusted thresholds and supplementary factors.
The headline PTV is almost always the wet result. A dry PTV of 60 is meaningless if the wet PTV is 22 — because slip accidents happen in the wet, not the dry. A complete survey reports both; an interpretation focuses on the wet.
Floors are not uniformly slippery in every direction. Ribbed vinyl, brushed concrete and directionally-textured tile can test well across the grain and poorly along it. A proper pendulum test is performed in two perpendicular directions and the lower value — the controlling direction — is reported as the governing result.
All measurements have uncertainty. A UKAS accredited report states the measurement uncertainty calculated from the laboratory's validation. A typical pendulum uncertainty is in the range ±1 to ±3 PTV. This means a reported PTV of 35 cannot be confidently distinguished from 36. Borderline results require more test repetitions or explicit re-characterisation.
The PTV depends on which rubber slider is used. Slider 96 (Four-S) is the default for shod-foot scenarios. Slider 55 (TRL) is for barefoot and historic highway applications. Results from the two sliders are not interchangeable — a PTV 36 with Slider 96 is not the same hazard profile as PTV 36 with Slider 55. A competent report specifies the slider used and applies the appropriate threshold.
PTV is a slip-resistance measurement. It does not measure:
A floor can have excellent PTV and be unsuitable on other grounds. The pendulum answers one specific question — is the surface slippery? — and it answers it well.
UKAS ISO 17025 accredited pendulum testing across the UK. Report within 5 working days.