Guide to Slip Testing
Duty of Care: Demonstrating Sufficient Compliance
The importance of slip testing. Slip and fall incidents are one of the main causes cited in personal injury litigation. As the onus is increasingly put onto cleaning companies, facilities managers and other stakeholders to be responsible for slip resistance, making an informed decision can be business-critical should an incident occur.
Just having the testing done may not be enough to reduce liability if it is proven that:
Appropriate testing methodology has not been employed,
Test results have not been properly interpreted and classified, and
Suitable control measures have not been implemented.
Your investment in slip resistance information for your floor surface(s) indicates your awareness of duty of care as an employer, owner, manager or occupier. In order to provide a safe working environment and safe access for visitors to your building.
In fulfilling your duty of care under the OH&S/WHS Act and the Wrongs Act, it is important to respond to the information you now have. Used appropriately, the information from your tests may reduce serious injury and assist in the event of any legal action.
Assessing the Risk
Your first step is to assess the risk along with relevant personnel; it may be appropriate to incorporate the outcome from your tests into a risk matrix. This will require you to determine the likelihood of a slip occurring (from your test results) and the consequence of injury. If you are unsure about the consequence of the injury, assume the worst – after all, falls from slips and trips constitute a large and costly public health problem in Australia with estimated health system costs to the public from related injuries being $1.28 billion per annum. This exceeds the cost of road injuries.
Australian standard AS 4663:2013 provides methods of measuring the frictional characteristics of existing installations, and may be used as part of an overall risk assessment procedure. It may also be used for evaluating the effects of surface treatments, including sealers, polishes and etchants which change surface characteristics.
Selecting the right test areas and appropriate method/s is the first step in constructing a suitable risk assessment. The choice of location/s as well as the number and type of tests must provide a complete and accurate representation of the site, and is dependent on the number of different flooring materials present as well as the probability of a range of contamination or exposure conditions, and nature of any anticipated activities.
The two test methods that are most used in Australia are:
Oiled Inclining Platform: Test as described as an option in AS 4586:2013. This is a laboratory only test and can only apply to new material surfaces intended to be installed in or on a pedestrian walkway.
Pendulum Test Method: This method can be used for new surfaces as per AS 4586:2013 but also more importantly for existing surfaces in-situ testing. It is well described AS 4663-2013 above. The Pendulum wet and dry testing is the most widely used assessment procedure in Australia.
The aim of AS 4663: 2013 is to provide methods of measuring the frictional characteristics of existing pedestrian surfaces in wet and dry conditions, and it is only used for existing installations i.e. in situ.
It is a useful tool for the evaluation of risk for facilities managers and floor maintenance businesses and may be used as part of an overall risk assessment procedure for public locations or buildings. It may also be used for evaluating surface applications and treatments, including products such as sealers, polishes and etchants that modify the surface characteristics of pedestrian surfaces.
The importance of AS 4663:2013 Slip resistance measurement of existing pedestrian surfaces is emphasised in the requirement that after handover, the surfaces cease to be ‘new’ and subsequent testing would be in accordance with AS 4663:2013.
The Wet Pendulum Test
Based on the pendulum test developed by the UK Transport and Roads Research Council, the equipment used is called a Portable Skid Resistance Tester, consisting of a heavy mechanical foot on the end of an arm which pivots such that the foot can swing in a vertical plane. Australian Standards require that the test be carried out wet.
Figure 1: Skid Resistance Tester and the Wet Pendulum Test
The foot of the pendulum arm is fitted with a Rubber Slider which has a specific hardness and resilience; either 4S or TRL rubber is used. In operation, a pendulum arm rotates about a vertical spindle: when released from a horizontal position, the arm of the pendulum passes through the bottom of its arc causing the slider to contact the floor surface for a fixed distance of 126-128mm. As the slider is at an angle to the floor, only the back edge of 75mm width sweeps across the floor; this causes energy to be absorbed, which is measured on a scale by the use of a pointer; the value is called a British Pendulum Number (BPN), which is recorded.
AS 4663: 2013 provides for a revised method for Wet Pendulum testing compared to AS/NZS 4663: 2004, to reflect more accurately, and provide greater discrimination, between the interaction of a worn or polished shoe heel and a smooth pedestrian surface. The change in method incorporates the use of 3µm lapping film as part of the rubber slider conditioning process, after conditioning on P400 grit sandpaper.
It is considered to better reflect the lower slip resistance attributable to the contact of two smoother surfaces under water-wet conditions.
Wet slip resistance testing can be performed using two types of rubber materials: Slider 55 (TRL) rubber, which has been traditionally used for testing outdoor surfaces such as roads and footpaths as well as wet barefoot areas, and Slider 96 (Four S) rubber which was developed to replace the Slider 55 rubber for testing smoother indoor surfaces, as it provides more discrimination. (The numbers ‘55’ and ‘96’ refer to the Shore A hardness of the rubber compounds used for each; the higher the number, the harder the rubber compound).
Whilst both rubber types can be used for the Wet Pendulum test method, only Slider 96 rubber is used for the Dry Floor Friction Test. The use of these two rubbers for wet and dry slip resistance testing allows direct comparison between slip resistance testing results.
Figure 2: Wet Pendulum Slider
Corrections for Slope and Temperature
For sloped areas, the slope correction formula and tables contained in AS 4663: 2013 and the same slope correction formula in HB 198: 2014 are used. Slip resistance testing conducted on a slope of ≥1.5° (2.6%) will have a Slope Correction Value (SCV) applied dependant on the maximum gradient of the area tested. The corrected results, where applicable, are applied to the Slip Resistance Value (SRV), under wet conditions, or the mean coefficient of friction under dry conditions and reported as the SCV within the results.
Wet slip resistance testing carried out using a Slider 55 rubber may have a Temperature Correction Value (TCV) applied dependent on the air temperature at the time of testing. The corrected results, where applicable, are applied to the Slip Resistance Value (SRV) and reported as the TCV within the results. Testing with the Slider 96 rubber requires no such correction.
As with any other scientific evaluation, test results must be reproducible within the allowed margin of error. Ensuring the standard’s exacting testing methodologies, including appropriate choice of wet pendulum ‘sliders’, conditioning for both the dry and wet methods, and implementing corrections for slope and temperature are key factors in obtaining both accurate and precise results.
A Slip ‘Test’ report is now generated, ready for interpretation as to classification and compliance.
Classification of Results
Test reports (recording data only) do not provide interpretative information on classification and compliance. While AS 4663: 2013 details the testing equipment and methodologies, it does not provide interpretative information or a classification system about what the results of the dry and wet testing mean. However, AS/NZS 4663: 2004 does contain information that estimates the notional contribution of the floor surface to the occurrence of a slip under wet or dry conditions. The guidelines in AS/NZS 4663: 2004, which have been used as acceptance criteria in the slip resistance testing industry since its release in 2004, have been used to interpret the test data contained in this report.
Tables 1 and 2 (below), reproduced from AS/NZS 4663: 2004, estimate the ‘notional contribution of the pedestrian surface to the risk of slipping under wet and dry conditions’. For reference, Table 2 has also been expanded upon to include the classifications provided in AS 4586: 2013. The only difference, other than the designation system, compared to the British Pendulum Number (BPN) classifications contained in AS/NZS 4663: 2004 and AS/NZS 4586: 20045, is that instead of a single classification for BPNs below 25, AS 4586:2013 references two classifications of 12-24 BPN and <12 BPN. This has become necessary because of the greater discrimination achieved incorporating 3µm lapping film
during conditioning, and the resulting higher sensitivity achieved when testing smoother surfaces.
Wet Slip Testing
Wet Pendulum slip resistance test results are analysed using Table 1 below which has been derived from Australian Standards AS/NZS 4663: 2004 and AS 4586: 2013.
Table 1: Analysis of Wet Pendulum Results
- *While either of these rubbers may be used, the test report shall specify which was used
- † The term ‘notional’ has been used to highlight the need to consider all potential contributing factors to a slip incident
- It is expected that these wet surfaces will be more slip resistant when dry
In Table 1, the term ‘Extremely High’ for BPN test results below 12 (AS 4586: 2013 classification P0) has been used. This terminology is not contained in any of the referenced standards, however Ecoshield considers this to be a reasonable and appropriate assessment and description of the pedestrian surface condition when such results are obtained.
Pendulum testing is normally carried out wet
Because the wet condition is when most slips occur and many floor surfaces permit the ponding of water, either accidentally or intentionally, the standardised test is carried out in wet conditions.
Guide to Interpretation: The SA HB 198:2014 Handbook
HB 198: 2014 contains useful and practical information about what minimum slip resistance classifications are appropriate for various public locations, including stairways.
The following paragraphs discuss the results against the classifications for the area types in accordance with Table 1 for wet pendulum test results (noted above). HB 198: 2014 establishes a basis for specifying pedestrian surface materials for various applications for new buildings and, therefore, is used here only as a guide.
Ecoshield does not accept any liability arising from its use. Compliance with the minimum classifications contained in HB 198: 2014 will not alleviate all hazards, although conformance will reduce certain risks.
Table 2B provides guidance for pedestrian surfaces for particular applications. The values represent a consensus view of Committee BD-094, although not all experts agree on all values. The values in Table 2B have been determined by the following process:
- Applications and corresponding values were selected initially from HB 197: 1999;
- A subcommittee of Committee BD-094 modified some applications and values, and these were further modified during the review process; and
- The contents of Table 2B are subject to further review by Committee BD-094, in its ongoing project to provide guidance on specifying and testing for slip resistance.
For completeness, Table 2A is also reproduced here from the previous Section.
There are some fundamental differences in the purpose and nature of Tables 2A and 2B.
- Table 2A applications and values have been determined by the Australian Building Codes Board for use in regulations based on the NCC. It provides the minimum wet pendulum test or oil-wet inclining platform test classifications that are deemed-tosatisfy specific applications in buildings covered by the NCC. These values may be used as acceptance criteria in a range of situations, including those where the building incorporates only the minimum regulated NCC requirements for handrails, lighting and the like.
- Table 2B applications and values have been determined by Committee BD-094 for use in applications that are not regulated by the NCC. It provides wet pendulum test or oil-wet inclining platform test classifications for applications where the NCC does not specifically require slip resistance. The applications listed are some of those for which slip resistance is warranted for reasons other than NCC compliance. The use of these values should be in the context of design, which also considers abnormal wear, maintenance, abnormal contamination, the presence (or otherwise) of water or other lubricants, the nature of the pedestrian traffic (including age, gait and crowding), the footwear (or lack thereof), slope, lighting and handrails.
Minimum Wet Pendulum or Oil-Wet Inclining Platform Test
Classifications Deemed to Satisfy NCC Building Applications
Note: NCC compliance is demonstrated by achieving the values set out in this table for either the wet pendulum test or the oil-wet inclining ramp test. It is not necessary to meet both criteria.
Wet Pendulum or Oil-Wet Inclining Platform Test Classifications
For Applications Where the NCC Does Not Require Slip Resistance
Notes to Table 2B
- The slip resistances of pedestrian surface materials set out in Table 2B are intended as guidance in the context of design for pedestrian safety, taking account other factors including abnormal wear, maintenance, abnormal contamination, the presence (or otherwise) of water or other lubricants, the nature of the pedestrian traffic (including age, gait and crowding), the footwear (or lack thereof), slope, lighting and handrails.
- The contents of Table 2B are subject to further review by Committee BD-094, in its on-going project to provide guidance on the specification and testing of slip resistance.
- The minimum classifications listed in Table 2B are P1 and R9. It is inappropriate for Table 2B to list the lower classification, P0, since there is no lower limit on Classification P0. Notwithstanding, some smooth and polished floor surfaces, which do not achieve Classification P1, may be considered to provide a safe walking environment for normal pedestrians walking at a moderate pace, provided the surfaces are kept clean and dry; however, should these surfaces become contaminated by either wet or dry materials, or be used by pedestrians in any other manner, then they may become unsafe. Therefore, the type of maintenance, the in-service inspection of floors, other environmental conditions and use should be taken in to account when selecting such products.
- When using the oil-wet inclining platform ‘R’ classifications, consideration should also be given to the determination and use of volumetric displacement ‘V’ classifications. In some cases, a specifier may choose either a particular combination of R and V values, or a more severe R value alone. For example, either R10 + V4, or R11.
Summary of Slip Testing
To evaluate the slip resistance under dry conditions, the test method in AS 4663: 2013 is used in accordance with the classification system in AS 4586:2013. For interpretation of test results, the criteria from AS/NZS 4663: 2004 pertaining to the notional contribution of the surface to the risk of slipping when wet are employed.
To evaluate the slip resistance under wet conditions, the test method in AS 4663: 2013 is used in accordance with the classification system in AS 4586: 2013 is used. For interpretation of test results, the criteria from AS/NZS 4663: 2004 are employed. When applicable, the obtained British Pendulum Number (BPN) test results are evaluated against both HB 198: 2014 and/or the relevant National Construction Code (NCC) section for stairways, for the required minimum slip resistance interpretation for such areas.
A Compliance Report must not only (1) state the test data, but also (2) deliver the assessment outcome stating conclusively whether (or not) defined minimal criteria have been met, (3) how the results have been interpreted in accordance with the standards, (4) what conclusions have been reached and (5) why – (6) as determined by someone with the relevant authority.
The objective of the Compliance Report is to make an unambiguous, defensible, clear and concise assessment, so that corrective actions and control measures are initiated to reduce risk, as required by your Duty of Care.
Limitations in Methodology
The passage of time, manifestation of latent conditions or impacts of future events may require further exploration at the site and subsequent data analysis, and re-evaluation of the findings, observations and conclusions expressed in this report.
Ideally the slip resistance of surfaces will be relatively stable; however, the performance of many seemingly slip resistant materials may vary significantly with time and usage conditions.
Control measures such as sufficient entry matting, awnings, air-lock doors, signage and cleaning regimes may help reduce risk or liability; remediation alternatives include grinding, surface treatments, or replacement of the floor.
If the risk cannot be eliminated one or more of the hierarchy of controls may be used to minimise the risk. Implemented control measures are then to be maintained and reviewed before the installation of new surfaces, when the function of the activity within an area changes, after advice that a slip related incident has occurred, or if a stakeholder requests a review.
If it is anticipated that the surface will become wet, control measures may further reduce the risk of an incident occurring on the surface. The floor should be maintained in a clean and dry condition with regular inspections to identify, isolate and clean spills and foreign objects. Actions should be in the form of immediate controls, which may include restricting access to an area, particularly if a disproportionate number of incidents have occurred which indicate that a surface is inherently slippery. In the longer term, it is recommended that prevention and engineering given preference as outlined within the Hierarchy of Controls (outlined below).
Usually, it is more appropriate to reduce the likelihood of a risk than it is to reduce the consequences of the risk. This can be achieved in a number of ways, as noted on the following page:
Table 3: Hierarchy of Controls
Regardless of whether your floor’s slip resistance results in a high or low level of risk, an appropriate plan to reduce the risk will always be beneficial. Ecoshield can recommend appropriate action be undertaken which may include, but not be limited to the points above.
Ongoing monitoring for wear and tear through regular testing will ensure the risk remains known, a responsible risk management plan is sustained and compliance demonstrated.
These are simple and effective ways you can reduce the risk of slips, trips and falls. Guidance available from Ecoshield can highlight other contributing factors to slips, trips and falls. To assist in your assessment of each of these, speak with Ecoshield consultants so that we may provide you with advice in the assessment and selection of the most appropriate solution for your floors and walkways.
Factors that Affect Slip Resistance – Slip Testing
1. SURFACE DETERIORATION
A significant contribution to slips, trips and falls is the deterioration of the floor surface or walkway over time. To account for this and subsequently reduce the risk of slips, a regular slip resistance testing program is recommended. Floors are often laid without regard to their durability. What might start out as a suitable surface for slip resistance, may deteriorate rapidly from the harsh effects of traffic and/or cleaning. So regular testing is most important. The frequency of tests depends on factors such as location and traffic.
2. NEW FLOOR SURFACES
If you are considering a new surface, its durability can be assessed on the basis of an Accelerated Wear Test (AWT). An Ecoshield provided AWT can indicate surface or surface treatment characteristics over time after subjecting the surface to controlled abrasion testing. This is a valuable method to assess suitability and compare proposed flooring surfaces or surface treatment products.
3. SURFACE TREATMENTS – Slip Testing
The application of surface treatments to existing flooring surfaces is an option that has gained popularity as the technology and the need for safer floors has grown. The increased range of options provides choice for clients but it can make a decision so complex it can hinder timely solutions.
Selecting the right surface treatment requires an understanding of options, their advantages and their weaknesses. Ecoshield’s team of technicians can guide you with independent advice on the selection of the most appropriate surface treatment for your circumstances to satisfy your need to increase slip resistance and/or prolong slip resistance characteristics.
4. BUILDING CODE REGULATIONS
Often overlooked in slips, trips and falls are contributing factors other than the condition of the floor’s surface. Building code regulations provide standards that we are obligated to comply with and conditions such as lighting, the slope of the floor and even stairway and handrail dimensions can contribute to slips, trips and falls.
Methods of Improving the Slip Resistance of Exisiting Floors
The following methods of increasing the slip resistance of floors is outlined in AS/NZS 3661.2:1994 Slip resistance of pedestrian surfaces – Guide to the reduction of slip hazards:
Table 5: AS/NZS 3661.2:1994 Slip Resistance of pedestrian surfaces – Guide to the reduction of slip hazards
It is recommended that when modifying the surface, samples of treatments be evaluated in terms of the increase in slip resistance and any other characteristic deemed to be important to the form and function of the floor surface. This may include but is not limited to:
- Mechanical properties
- Chemical properties
- Surface adhesion
Control measures and remediation schemes are not ‘one-size fits all’, the choice of suitable products and services depends on the flooring materials used as well as other relevant practicalities. Companies responsible for specifying recovery schemes can get into trouble with misidentified materials, ill-chosen surface treatments (e.g. unsuitable slip and adherence properties, or causing degradation), and the ever-present battle between cleanliness and slip resistance. A rule of thumb is to undertake test patches on discreet areas before committing to the entire project and major capital expenditure.
A trial of suitable options will provide the required information to conduct a cost-benefit analysis of the identified treatments. When considering the selected treatment the long term sustainable slip resistance should also be assessed.
Conclusion on Slip Testing
In the event of a slip incident, liability may not be eliminated, but if due diligence has been conducted as part of an overall risk assessment and an appropriate standard of care has been implemented, exposure will in most cases be minimised and the well-being of all parties safeguarded as far as reasonably practicable.
1. Australian Standard AS 4663: 2013
Slip Resistance measurement of existing pedestrian surfaces, Standards Australia
2. Australian Standard AS 4586: 2013
Slip resistance classification of new pedestrian surface materials, Standards Australia
3. Standards Australia Handbook HB 198: 2014
Guide to the specification and testing of slip resistance of pedestrian surfaces, Standards Australia
4. Australian and New Zealand Standard AS/NZS 4663: 2004
Slip Resistance measurement of existing pedestrian surfaces, Standards Australia
5. Australian and New Zealand Standard AS 4586: 2004
Slip resistance classification of new pedestrian surface materials, Standards Australia
6. AS/NZS 3661.2:1994
Slip resistance of pedestrian surfaces – Guide to the reduction of slip hazards, Standards Australia
For more information or to book in your next slip test, contact us