he HSE has, over the last year, been targeting its inspections on top-slewing tower crane sites. Since 2000, seven people have died in three tower crane incidents in Canary Wharf, London; Worthing, West Sussex; Battersea, London; and Liverpool. About 2,000 people work in the UK industry, HSE specialist investigator for tower cranes Ian Simpson told an open meeting of the UK Construction Plant-Hire tower crane interest group. He concludes that there are around 50 fatalities per 100,000 workers per year. That figure is 14 times last year’s construction fatality figure (3.5) and 71 times the general industry fatality figure (0.7).
Tower cranes are being targeted by safety checks in the UK
Simpson showed that the highest proportion of incidents occur from things falling from a crane. But he added that his analysis of the statistics led him to believe that the industry is under-reporting dangerous occurrences—when a crane fails—as required by law. In an additional point-by-point review of the HSE safety alert, later in the meeting, he added that he has ’little evidence’ that companies were fulfilling their legal obligations to notify the HSE when major faults were discovered on cranes during examinations.
In the UK, top-slewing tower cranes must have a thorough examination before they can be first used; self-erectors need only undergo a functional check. The issue of exactly who can carry out such an examination provoked controversy. Simpson proposed that this work could be carried out by someone “sufficiently independent and impartial” within the company, as well as an external examiner. This suggestion met with criticism from a few attendees at the meeting.
“That’s a complete 180-degree turn,” one said. Another attendee said that it was a conflict of interest for the person in the company with the most tower crane experience, the lead erector of the crane, to essentially approve his or her own work. Another said that because tower cranes are usually erected at the weekend, it was common practice in the UK for the crane to be erected, signed off by the lead erector, and used for up to 72 hours before being thoroughly examined by an external examiner.
Simpson reiterated that UK law requires a thorough examination before the crane can be used. He added that he is simply following the the LOLER regulations that underlie crane use in the UK. LOLER says that the examiner can be external or internal. He said that if companies were using internal examiners, HSE inspectors would be looking for evidence of independence and impartiality. They would want to see records of the training and competency assessment of the examiner, and copies of written guidance on the scope of the examination and of acceptance criteria (for example, the amount of backlash on the slew ring gear that the examiner considers acceptable). They would also want to see evidence that examiners were given feedback about their examinations and their suitability.
There are two good reasons why crane firms should use an independent examiner, argues Richard Hulmes, chief executive of UK inspection association the Safety Assessment Federation (SAFed).
First, they do not have a commercial interest in any further work exposed by an examination, so they would not want to pick up a minor fault in order to sell tower crane users the fix.
Second, they are not inspecting their own work, so they come to the tower crane from a different perspective. “We don’t practice putting up cranes so we wouldn’t neccessarily be able to put one up quickly, but what do have is the competence to do a proper risk assessment of the whole process,” Hulmes says. “Our members’ engineers and surveyors won’t know the location of every single grease nipple, but they will carry out a risk assessment, assess the deterioration of the crane, look at lifting operations, review working conditions and weather conditions. That may not be necessarily the primary activity of the contractor.”
Nick Fraser, Imes cranes and lifting equipment chief engineer, added: “Conflicts of safety are less likely to arise if independent thorough examinations are implemented by a reputable company experienced in lifting appliances, rather than in-house by the crane operator or owner.”
Imes, which is not a member of SAFed, uses risk-based inspection (RBI) o determine what to inspect, Fraser says. “In operational equipment such as cranes, a high proportion of the risk is associated with a relatively small percentage of the equipment. RBI permits the shift of inspection and maintenance resources to provide a higher level of coverage on the high risk areas and an appropriate effort on the lower risk aspects.”
Fraser continued, “The RBI methodology defines the risk of operating cranes as a combination of two separate terms: the consequence of failure and the likelihood of failure. A ‘failure’ could be a dropped load, snagged load or uncontrolled motion causing stresses outside the intended design basis envelope. Imes has demonstrated how risk-based inspection can be applied to underpin life extension for cranes nearing the end of their theoretical design life.”
