Some products are easy to plan and design; others are more complicated and require more precision and care. A product that was particularly challenging for designers was the fall harness. This product is used widely by construction workers and is used to prevent falls. It is not widely known that falls are the leading cause of death for construction workers on the job. In addition to safety concerns, many construction workers reported that wearing the harnesses were uncomfortable, so they resisted wearing them altogether.
Project Origin
The safety of U.S. construction workers is enhanced by wearing full body fall-protection harnesses. Yet, very little had been known about the fit of these harnesses or the anthropometric characteristics of the population that wore them.
In 2001, the National Institute for Occupational Safety and Health (NIOSH) wanted to focus on fall harness safety. They reached out to Anthrotech in order to measure construction workers and collect 3D scans of people while wearing and using the harness. The goal was to make a preliminary investigation into both the fit of fall-protection harnesses, and into those anthropometric characteristics of those who wear them.
How Anthrotech Helped
Our study centered around two, widely-available types of harnesses – an overhead type and a vest type. We knew it was important to scan people while they were both standing in the harness and suspended in the harness. Comparing the suspended to standing scans allowed us to analyze the results of each scan to determine if a change in harness shape was needed. To our knowledge, this was the first time people were ever scanned while suspended in fall-protection harnesses.
With the help of our subcontractors, each of the nearly 100 subjects were scanned using the Cyberware WB4 scanner, in addition to being measured with traditional instruments. There were three separate scans completed of each individual. The standing scan with the harness allowed visualization of the relationship between the harness and the subject. A second scan with the harness showed how that relationship changed when the subject was suspended from a cable attached to the harness. This scan simulated post-fall suspension, a critical context for harness fit. The final scan was done without the harness, and allowed the comparison of measurements extracted from the scan with similar measurements taken in the traditional way.
Results
As a result of the pilot study, we pinpointed areas where existing harnesses were sufficient and where improvements were needed. We were able to develop fit criteria for harnesses. Multiple fit criteria were identified, including where the shoulder strap should fall across the shoulder, how snug certain straps should be and at what degree the body should be held vertically in suspension. With the help of the NIOSH, the criteria were shared with fall harness manufacturers, enabling them to produce safer and more comfortable harnesses for construction workers.
In addition to the fit criteria development, the study enabled us to develop a pilot anthropometric database for U.S. construction workers. We also pioneered a way to characterize the 3D shape of the individuals in the pilot database, so they could be represented in various computer modeling programs that might be used to simulate falls, and thereby improve worker protection.
It was gratifying to take part in a project that worked to increase the safety of construction workers on the job, and we look forward to more opportunities to help make products safer for men and women.
