The HSE Pendulum Test Value bands — 0–24 high slip potential, 25–35 moderate, 36+ low — are the foundation of UK pendulum interpretation. They are not a legal threshold but an interpretive guide. Understanding their derivation, their regulatory weight, and their limitations is central to using pendulum data in any defensible way.
| PTV (wet, Slider 96) | Slip potential | Approximate probability |
|---|---|---|
| 0 to 24 | High | Approximately 1 in 2 |
| 25 to 35 | Moderate | Approximately 1 in 20 |
| 36 and above | Low | Approximately 1 in 1,000,000 |
The probability figures are approximate, derived from research carried out by the HSE and TRL over many years comparing pendulum results with reported slip incidents.
The bands have their origin in research carried out from the 1970s onwards by the Transport Research Laboratory and HSE. By correlating pendulum results from sites where slip incidents had occurred with results from sites where they had not, the researchers identified threshold values that broadly separated 'safe' from 'unsafe' surfaces in pedestrian environments.
The 36+ threshold has been remarkably stable since this work. It appears in HSE guidance documents, in BS 8204, in NHS specifications, in insurance schedules, and in case law. The robustness of the 36 figure across decades and sectors is itself a feature.
HSE guidance is not law in the strict sense, but it carries substantial weight in UK courts and tribunals. The general legal framework is the Health and Safety at Work etc. Act 1974, which requires employers to ensure (so far as is reasonably practicable) the health, safety and welfare of employees and others affected by the work. Whether 'reasonably practicable' has been satisfied is a fact-specific judgment, and HSE guidance is the principal benchmark for what reasonable practice looks like.
In a slip claim involving a floor below PTV 36 wet, the HSE bands provide the framework for arguing that the slip was foreseeable and that reasonable practicable steps had not been taken. Conversely, a floor at PTV 40+ wet evidences that the relevant HSE benchmark has been met.
The 25–35 moderate band is the hardest to interpret. A floor in this band is not in clear breach of HSE guidance, but it is also not clearly compliant. Whether such a floor is acceptable depends on:
Pendulum reports for moderate-band results typically include qualified recommendations rather than a single pass/fail.
The HSE bands are interpreted against wet PTV in environments where wet contamination is foreseeable — which is almost all UK pedestrian environments. For genuinely dry-only environments (interior warehouse aisles, dry archive stores), dry PTV is the relevant value, and the bands apply to that dry value. Confusion between wet and dry application is a common source of misinterpreted reports.
The HSE bands are an interpretive starting point. They do not capture every relevant factor. A PTV 38 wet floor may still produce slip incidents if:
Interpretation of pendulum data is therefore always contextual, even when the band is clear.
Tell us about the site and we'll come back with a quote within one working day.
Request a Quote