One of the best ways to prevent and control occupational injuries, illnesses, and fatalities is to “design out” or minimize hazards and risks early in the design process. The National Institute for Occupational Safety and Health (NIOSH) is leading a national initiative called Prevention through Design (PtD) to promote this concept and highlight its importance in all business decisions.
The concept of PtD can be defined as Addressing occupational safety and health needs in the design process to prevent or minimize the work-related hazards and risks associated with the construction, manufacture, use, maintenance, and disposal of facilities, materials, and equipment.
A growing number of business leaders are recognizing PtD as a cost-effective means to enhance occupational safety and health. Many US companies openly support PtD concepts and have developed management practices to implement them. Other countries are actively promoting PtD concepts as well. The United Kingdom began requiring construction companies, project owners, and architects to address safety and health during the design phase of projects in 1994, and companies there have responded with positive changes in management practices to comply with the regulations.
Australia developed the Australian National OHS Strategy 2002-2012, which set “eliminating hazards at the design stage” as one of five national priorities. As a result, the Australian Safety and Compensation Council (ASCC) developed the Safe Design National Strategy and Action Plans for Australia encompassing a wide range of design areas including buildings and structures, work environments, materials, and plant (machinery and equipment).
In past years, many conventional safety management professionals have focused their attention on hindsight, rather than foresight. This means that safety-by-design becomes a priority only after a record of previous serious injuries, deaths or costly damage have occurred from the same hazard.
In 40 years of observing heavy construction progress in America, this reporter has seen two examples where it took a fatality to move a contractor to action and give safety a top priority. In one case, an unsafe act in a tunneling project caused the death of a worker. In the other instance, a worker fell into a cold aggregate feed bin at an asphalt plant that was running. The worker was sucked into the sinking aggregates and died. After that, the company redoubled its safety focus from the top down.
So it is heartening to see David MacCollum, PE, CSP, and a member of the International Safety and Health Hall of Fame, reporting that a select few large design-and-build construction and mining companies are now making the choice of foresight over hindsight. Writing in the Journal of System Safety, MacCollum says root-cause analyses usually identify an unsafe behavior as the cause of workplace injuries and deaths. System safety, MacCollum says, is applying scientific knowledge to ensure safe design by eliminating hazards.
“Why are these select few construction companies adopting a foresight philosophy?” MacCollum asks. It is because they have learned the hard way that waiting until someone is killed is a costly way to identify hazards. MacCollum says progressive construction managers state the need for engineers knowledgeable in design-based safety to review-before work begins-project design and construction methods to identify hazardous conditions and circumstances and to provide safe alternate design features. These same progressive project managers are looking for designs that eliminate hazards, rather than hoping that workers will avoid the danger. These managers know that hazards are often hidden from workers’ view and are not apparent to the design engineer, estimator, construction engineer, supervisor, or worker.
Many examples show, MacCollum says, where the skills of the system safety engineer can be expanded to make a significant reduction in the injury and death rates currently experienced in construction. For starters, MacCollum points to the failures of simple nuts, bolts, pins, and other connectors as sources of unseen hazards. Several years ago, a bridge collapsed in Minneapolis, MN, because half-inch-thick connecting plates were mistakenly substituted for 1-inch-thick center plates used to connect the two legs at the apex of each structural arch. The defect went unnoticed for nearly 30 years as the bridge was being maintained and upgraded to include new traffic lanes. The collapse occurred at rush hour and many lives were lost.
Design-based safety includes a system to double check to ensure that the actual design specs are in place. Nuts and bolts on backhoes and on crane and aerial lift turntables can easily become loose or stressed from the vibration inherent in normal usage. Vibration can also cause fatigue cracks to grow over time, causing the nuts to come loose and the bolts to break.
Design-based safety, MacCollum says, should ensure several important factors:
* A high level of nut-to-bolt friction to prevent loosening
* Bolts that are of sufficient diameter to resist tension stress and fatigue
* A thorough understanding of the chemical content of the steel in nuts, bolts, and connector plates to determine their vulnerability to hydrogenation
* Full compliance with pertinent Society of Automotive Engineers (SAE) standards
* An evaluation, at the time of design, of the vulnerability of all connectors to the hazard of vibration that causes tension stress
Unsafe design of cranes and aerial lifts has caused turntables to collapse when these factors were not taken into account, and these collapses have resulted in wrongful-death, personal-injury liability lawsuits.
System safety has proved itself as a necessary function of aircraft and aerospace design, MacCollum says. The new frontier is to take this expertise and expand it into the fields of construction, energy, mining, rail transportation, and petroleum extraction and refining. As our industrial development continues to become ever more complex, engineers with expertise in system safety need to be employed to lead the way for design-based safety.
