While quite rightly much attention is given to ensuring workforces wear suitable footwear, it’s important to get to the base of the matter – quite literally, to the floor. Engineering consultants Mark Pillinger and George Sotter join forces to discuss Sustainable Slip Resistance in a bid to minimise a commonplace hazard – slips and falls in the workplace.
The widely accepted principle of safety by design, as well as laws and building codes, requires flooring to be slip-resistant over its entire life cycle – not just at the time of installation. Safety criteria based solely on static coefficient of friction, often used for assessing safety, are too often misleading where flooring gets wet or otherwise lubricated in use. More than 150 safety criteria have been adopted in Germany and Australia for specific situations – swimming pool decks, commercial kitchens or restrooms, for example.
Many industrial environments have similarly stringent safety criteria. These are based on a laboratory test device – the variable-angle ramp – which is not readily portable. The pendulum tester, on the other hand, is a portable ASTM (American Society for Testing and Materials) method, has been used successfully since at least 1971 for assessing pedestrian traction potential, and is a national standard for pedestrian traction in 44 nations on four continents. Abrasion of a flooring sample, tested with the pendulum before and after, is being used to assess ‘Sustainable Slip Resistance’.
Some architects and property owners are now combining this pendulum based test with situation-specific safety criteria to specify and verify safe flooring.
The purpose of this article is to provide an overview of a particular testing method and selection criteria for use in choosing and sourcing slip-resistant flooring that maintains good tribological characteristics over its life cycle. The test method is known as Sustainable Slip Resistance (SSR), and together with situation-specific safety criteria is becoming an established methodology in certain international venues.
In safety engineering it is widely accepted that ‘safety by design’ is the most reliable method of preventing accidents. People should not be expected reliably to use safety equipment (e.g. slip-resistant footwear) or exercise special caution (‘slippery/wet floor’ warnings). If flooring is in an area where it can get wet or otherwise lubricated, it needs to be slip-resistant under such conditions.
Although it is sometimes assumed that flooring slip resistance never changes with time, this is not true. Wear from shoes plus abrasive soil or other contaminants on a busy floor, or certain inappropriate maintenance practices, can in some cases reduce the wet slip resistance in a matter of weeks – or even in an hour. Post-construction cleanup using an abrasive pad has in a number of instances destroyed the slip resistance before a building was even opened. The Americans with Disabilities Act (ADA) requires that flooring accessible to disabled persons is slip-resistant – not just when the building is constructed, but throughout its lifetime.
Typical building codes in the USA require that “Every existing building, structure, premises or portion thereof shall be maintained in conformity with the code regulations and Department approvals in effect at the time of such construction and occupancy… Every existing building, structure, or portion thereof shall be maintained in a safe condition and good repair… All physical elements of every existing building, structure or portion thereof shall be maintained… by restorative means, in a condition as close as reasonably feasible to their originally required and approved state.”
If a building owner can be confident that his or her new flooring will sustain its slip resistance for a period of years, this can protect a considerable investment in the flooring and prevent business interruptions as well as protect the safety of the pedestrian. The stakes are even higher for hotels and cruise ships, which are occupied virtually nonstop with guests who will not tolerate the noise involved in changing out hard flooring.
Sustainable Slip Resistance (SSR) testing was developed by Strautins (2007, 2008) in Australia for McDonald’s Restaurants to identify flooring that is not highly susceptible to loss of its slip resistance from wear or some types of inappropriate maintenance. With obvious applications within an industrial context, this test and appropriate selection criteria can help avoid investment in inappropriate flooring as well as prevent costly, life-altering accidents and increased healthcare costs. This paper explains the method and how it can be used to improve flooring safety.
Test methods and safety criteria
For more than ten years Germany and Australia have had detailed flooring slip resistance standards based on some 150 specific situations – from external walkways to hospital operating rooms. Many architects elsewhere in Europe have informally adopted them. The slip resistance ratings are based on humans walking an oily or wet flooring sample in standard footwear and/or bare feet on a laboratory variable-angle ramp, the repeatability of which was extensively documented1. The test results apply only to flooring before it is installed, however.
Since 1971, the United Kingdom has had well established slip resistance standards based on a portable test method, the pendulum. This test was developed for pedestrian traction by the US National Bureau of Standards in the 1940s and further refined in the UK2. It was validated for pedestrian traction in 1971, together with its safety standards, in the UK over a period of 25 years by 3,500 real-world public walking area tests and site accident records3. The test is an ASTM standard (E 303), slightly modified for pedestrian traction.
Architects and designers generally look for a wet static coefficient of friction of 0.60 or higher by ASTM method C 1028 to assess potential safety for wet areas of level floors. This can give deceptive results, applying ‘safe’ ratings to some flooring samples that are in fact very slippery when wet4. The method is now acknowledged by ASTM (2005), Ceramic Tile Institute of America (2001b), and Tile Council of North America5 to be inadequate for assessing safety. The ASTM C 1028 method does not represent the most current state of knowledge about testing methods, but this is not widely known by architects and property owners.
An objective in this section is to correct this situation and suggest a more useful test and safety standards (safety assessment) for due diligence based on the pendulum. The pendulum is now a standard test method for pedestrian slip resistance – European Committee for Standardization EN 13036-4, 2003 names many of the nations using it.
How SSR works
The SSR test procedure consists of an initial wet pendulum test; abrasion, wet, for up to several thousand cycles with a standard 100×100 mm abrasive pad under a standard load of 1 kg at 50 cycles/min; and another wet pendulum test after abrasion. Both hard and soft rubber pendulum sliders (or ‘test feet’) might be used if the area is walked on in both hard-bottom footwear and bare feet or soft-soled footwear.
The abrasion is conducted either manually, or mechanically using a linear washability and wear tester. Typically, about 85 percent of the loss in slip resistance after 5,000 cycles has already occurred after 500 cycles6. Depending on the flooring buyer’s situation, the flooring might be considered to have Sustainable Slip Resistance for a level floor if, for example, the wet Pendulum Test Value (PTV) is 35 or higher after abrasion for 500 cycles. The 500 cycle result in the laboratory has been found by in situ pendulum tests to be roughly equivalent to six to 12 months of wear in customer areas at a busy McDonald’s Restaurant. The 500-cycle specification was adopted by McDonald’s in Australia in October 2006. Other major property owners such as Aldi, Toyota, Westfield and a major cruise ship company have adopted similar specifications.
Flooring with SSR is available in ceramic tile, natural stone, and resilient products. Abrasive-containing coatings, some transparent, are also available that have SSR. In some cases, analogous to the variable-angle ramp test-related standards mentioned above, the SSR safety standards are situation-specific7 rather than ‘one size fits all’. Thus, a minimum pre-abrasion wet PTV of 35 might be required for hotel or hospital bathroom floors; a minimum of 45 (hard rubber slider) for stair nosings that get wet in use; and 54 (hard slider) for commercial floors and steep outdoor ramps.
If the flooring is to be sealed after installation, the laboratory tests should be conducted with the correct sealer applied. Cleanability tests with expected contaminants by owners and/or other duty holders are also advisable before final selection of flooring. The methods of cleaning8 should be planned. (A dirty mop with dirty water might not be adequate for non-slip flooring, but abrasive pads can destroy wet slip resistance quickly).
Experience has shown that what is specified and ordered is not always what is delivered, and it is prudent for property owners to verify that flooring meets their slip resistance specification both before installation and at turnover of the property for occupancy. Monitoring of slip resistance every three to 12 months after that can further protect pedestrian, owner, and other duty holders.
Importance of entrance matting
Having a high-quality entrance mat in your facility is important for many reasons. When entering a building, you want to start with a good impression to your guests. Having a clean entrance way indicates care, responsibility and trust. It sets a positive tone right from the first step. Most business owners realise that providing a safe environment for their customers is essential. Entrance mats are one of the most important ways that you can ensure that floors remain clean and safe for customers and employees.
High quality entrance mats can absorb water, snow, dirt and other debris which can not only cause slippery floors but can make the entire establishment seem unkempt. Keeping both your staff and customers safe is high on the list when choosing a quality mat for your facility. No one needs a liability issue and having a mat to prevent slips and falls is a great peace of mind. With no mat or even a small mat your company is increasing the risk of slips and falls. Besides the health and safety risks, having good entrance matting will decrease your cleaning bills.
An efficient matting system will minimise business interruption by reducing the cleaning cycle and thereby promoting a professional and welcoming entrance. 42% of the floor’s finish can be removed with the first six feet of the entrance after only 1,500 people have walked on it. About 85% of dirt and moisture that comes off footwear into your facility comes in from outside. This is tracked in from the different entrances within your facility. Did you know that .58g of moisture comes in with each person and can be multiplied up to ten times that on a rainy day?
One of the best ways to control this issue is with a good matting programme. Start with proper quality exterior and interior mats at every entrance point. Having a mat outside the door to scrape off dirt, followed by a mat inside to soak up excess moisture is the best way to optimise your matting and reduce cleaning costs. Routine cleaning of the mat will also prolong the mat’s life span and be more likely to stop the dirt and grime at the door.
The walking distance over a mat is of utmost importance. In this case, bigger is most definitely better. With every metre walked over the mat, a certain amount of dirt is left behind. The longer the walk-off area, the more effective the mat will be. Therefore size and shape are an important consideration when choosing a mat for your facility. Preferably, you want to cover five to seven steps to remove the dirt from the soles of your shoes. Bear in mind that the average adult step is three feet, so you should have an entrance mat of 15 – 18 feet into your entrance, which will make your premises a lot safer.
1. A woman worked as a technical instructor in a large hospital. On entering the main hospital while taking post to the sorting office she slipped on decomposing leaves on the concrete steps. Fresh leaves had also fallen on top indicating the decomposing leaves had been there for some time. Falling heavily onto her right knee, she went home and returned to work the next day, although her knee was extremely swollen, painful and still bleeding. She was sent to hospital where it was sutured and x-rayed and it was found that she had damaged her kneecap. Still in pain three months later she was told that she needed surgery. The leaves were supposed to be cleared on a daily basis, but due to staff shortages this was not done.
Six years later she slipped again, this time on an unmarked wet floor, falling directly onto her right ankle and breaking it. After having her foot in plaster for six weeks, her foot remained contorted once the plaster was removed. Over the next few years she faced some 32 operations to try to save the foot, and was eventually told that she had dystonia caused by the accident, and that amputation was the only solution as her toes had lost their feeling and were turning black. One week after her fall the floors in the unit were made non-slip.
2. An employee in a pine factory slipped and cut himself on a poorly guarded machine. As a result of this injury, HSE served a health and safety improvement notice on the company because the floor was found to be unacceptably slippery even in dry conditions. In addition, it was also found that furniture wax was being transferred directly onto the floor as products were being pushed around the factory and this may have contributed to the original accident. The solution was to introduce trolleys to move large items of furniture around the factory. This also helped to reduce manual handling. Areas of the floor around machinery were also painted with an anti-slip treatment to improve the slip resistance in these areas where people were working close to other hazards.
Sustainable Slip Resistance as a test method and formal or informal standard provides advantages over formalised and standardised test methods currently in place, in that it addresses a most important component of product utility: the ability of the test method to assess potential product wet slip resistance over its life cycle.
The ability of the surface to maintain its slip resistance over time and with wear is a significant aspect of product use, and the informal adoption of this standard as part of due diligence potentially establishes conformance with the state of the art in surface slip resistance determination.
1 Jung and Schenk, 1988 2 Giles et al, 1964 3 Greater London Council, 1971, 1985 4 Powers et al, 2007 5 Astrachan, 2007 6 Strautins, 2008 7 Strautins, 2008 8 Tari, Brassington et al, 2009
The authors are grateful to Carl Strautins, Richard Bowman, Terry Tyrrell-Roberts, Dr Wen-Ruey Chang, and Paul Keane for their helpful input. Author Details: Mark Pillinger and George Sotter, Safety Direct Global. Mark Pillinger is a Slip Resistant Engineer and Health and Safety Advisor at Safety Direct Global. Technical areas include chelating agents, emulsion polymerisation, surfactanta and dispersing agents, water soluble monomers and polymers, anti-scale andanticorrosion products, antioxidants, pigments, light stabilisers, oil soluble additives and biocides. Research, and Product Development: Chemical development, re-use of chemicals, research and development projects, and many aspects of industrial chemicals. Specialities: industrial chemicals; management of research; development of speciality and effects of chemicals; development in the applicational fields of water treatment, water soluble polymers, chelating agents, oil additives and polymer additives. Projects undertaken include: inorganic pigment treatment; water purification by reverse osmosis; PVC compounds for profiles; desalination chemicals; purification and re-use of chemicals; additives for polyolefin’s; health and safety systems in water treatment; deodorising compounds. Current Projects include research on slip resistance on acrylic polishes. Technical areas worked in: Chelating agents, emulsion polymerisation, surfactanta and dispersing agents, water soluble monomers and polymers, antiscale and anticorrosion products, antioxidants, pigments, light stabilisers, oil soluble additives and biocides. Lecturer on Slip Resistance, Slip Resistance Instrumentation, Measurement Methods and Measurement Skills. Health and Safety Qualifications: Competence in use of Tortus 11 microprocessor and British Pendulum Test Meter. Inclined Platform (German Ramp.) Testified on slip resistance issues in Europe and Middle East. T: +31 73 684 3000 E: [email protected] George Sotter PE, PhD Engineering Consultant and Expert Witness – Slip, Trip and Fall, Sotter Engineering Corporation. Consultant/expert witness in slip, trip and fall litigation at locations ranging from Guam experience to Bermuda. Project Manager and Principal Investigator of OSHA-driven one-man-year project to minimise slipping incidents on construction site steel products. Laboratory and field testing of pedestrian surfaces for slip resistance. Consultant to Carnival Cruise Lines in slip reduction. Member of eight national organisations, in two nations, relevant to slip resistance affiliations of pedestrian surfaces. Chairman, Ceramic Tile Institute of America’s Slip Resistance Committee. Member of American Society for Testing and Materials (ASTM) and American Society of Mechanical Engineers (ASME). Author of a number of books and more than 35 papers, articles and other publications in technical trade magazines, international symposia, and archive journals. Includes several addressing pedestrian falling accidents. Licensed as a Professional Engineer (Chemical) by State of California Board for Professional Engineers and Land Surveyors (current, since 1971), and (on as-needed basis) five other states. One of four United States slip and fall consultants recommended by AM Best in 2011 Best’s Directory of Recommended Insurance Attorneys and Adjusters, Volume II, p.178. More than 45 years in consulting and engineering. Slip and fall forensic consulting for both plaintiff and defence, in roughly equal proportions. T: 1 800 988 6721 E: [email protected]
Published: 01st Jan 2012 in Health and Safety International