New ladder research calls for AS1657 rethink
The draft revision of AS1657, which covers the selection, design, risk assessment and testing of fixed platforms, walkways, stairways and ladders, needs further revision, according to ergonomist, Professor Caple.
The draft revision of AS1657, which covers the selection, design, risk assessment and testing of fixed platforms, walkways, stairways and ladders, closed for public comment in September 2012. But, it may well need further revision, according to ergonomist, Professor Caple, who believes a study he conducted has delivered a host of findings warranting larger research into equipment design.
“Some of the issues that have come out of this study could be deemed to be life saving if the behaviours that we saw could be repeated in a larger study using a broader section of the population,” Caple states. “If those behaviours are indicative, then we have found some risks that do need to be addressed.”
The Caple study, which was sponsored by Workplace Access & Safety, involved analysis of videotaped footage of Australians as they used various types of ladders. Among the outcomes were that falls are more likely from a vertical rung ladder than an inclined step ladder. Professor Caple also found extended stiles that allowed users to maintain their hand grip while stepping down onto the first rung of a ladder reduced the risk of falling.
“When we have a system where the hands are behind the shoulders and the centre of gravity of the body is moving backwards, we have a significant risk of falling,” Caple notes. “What we are looking for in the design standards is an appreciation that bodies move in a three-dimensional space and that space is dictated by gravity. What they need to maintain is good support using their three points of contact regardless of whether it’s an angled or a vertical ladder, particularly as they transition from the top of the ladder on and off the landing.”
The design of treads and rungs also influenced the likelihood of injury. The spacings, radius or width and even the distance from the wall were all important. “If the stiles and or the treads on the vertical ladder are too close to the wall, it increases the potential for someone to fall because they haven’t got good stable support of their foot to stabilise their centre of gravity over the tread,” Caple states.
“Because they [the ladder users who were the subject of the study] couldn’t see the treads on a vertical ladder as they were going down, they tended to, when they got to that bottom tread, either look down and then take a more careful step onto ground level or they might stumble and miss it completely,” he adds. “It was more problematic when the bottom tread was close to the floor. We learned that, as a principle, it’s a good idea to have equal distances between the treads from the floor height to the landing height.”
The Caple research has been welcomed by the AS1657 review committee, says one of its members, who is also the study’s sponsor, Carl Sachs of Workplace Access & Safety. “I commissioned this exploratory research to test some of the assumptions the committee was making while drafting the revision of AS1657,” Sachs comments. “This standard deals with some very serious risks, so it’s vital that its recommendations are manageable and add to everyone’s safety. Professor Caple has found there certainly are questions that need to be answered and I hope this will encourage larger research to be sure AS1657 really is on the right track.”