Edited by Rowena Davis

Part 3:

Five Principles of Inherently Safer Design

One potential method of achieving PPD is multi-party use of the Five Principles of Inherently Safer Design, mentioned previously in this study and outlined in the new book by McGraw-Hill, Construction Safety Engineering Principles: Designing and Managing Safer Job Sites (2007). This program has been adopted by construction giant Washington Group International (WGI), which is training 1,800 of their engineers in the five principles of inherently safer design. In addition to WGI’s training, these design principles have been presented at national safety conferences⁸ and published in the May, 2006 issue of Professional Safety, the journal for the American Society of Safety Engineers (ASSE). Through emphasis on hazard identification in the initial stage, the Five Principles can be used as a reference point by owners, architects, design engineers, equipment designers, construction managers, and subcontractors during discussion and planning of the project. Further application is discussed below in a brief outline of each of the principles.

⁸ The Construction Safety Council, Chicago, IL February 2007; The Oregon Governor’s Safety Conference, Portland, OR, March 2007.

Principle One

Identify the hazard: Every hazard appears in one of three modes: Dormant, when the hazard exists but is unable to cause harm; armed, when the hazard is in a situation where a change of circumstance could trigger the hazard to cause harm; and active, where the hazard is actively causing harm. The ability to identify hazards in the dormant mode is key to preventing them from becoming active and causing harm on a construction project. Overhead powerlines present a dormant hazard that becomes armed when boomed equipment is working next to it. This hazard becomes active when the equipment makes contact with the powerline, electrifying the metal parts with deadly voltage. PPD aids in identifying the presence of powerlines and potential controls in the planning stage by documenting all potential hazards from a variety of sources. The owner, architect and construction manager create individual lists of potential hazards on the same project, then match these hazards to hazards anticipated by sub-contractors, equipment rental firms, and other entities involved in the project. The result is a broad overview of many facets of potential hazards that can be planned around.

Principle Two

Establish a standard of care: When hazards are identified, it is imperative that the culture demands immediate hazard control. A popular safety tenet states “Any hazard that has the potential for serious injury or death is always unreasonable and always unacceptable if reasonable design features and/or the use of safety appliances are available to prevent the hazard.” This approach creates a priority for safety and prevents injuries and damage from occurring.

The creation of such a priority would invite the designer to include preventive designs in project plans to eliminate potential hazards, such as removing all powerlines from a construction area. In the collaborative context of Progressive Project Delivery, it would creates a guiding priority and a common goal to unify the myriad voices involved in the project.

Principle Three

Categorize the Hazard: Each hazard can be classified according to its nature into one of seven categories. Placing the hazard into its appropriate category helps determine methods of its control. In PPD, this categorization is helpful as a first step in determining the significance and classification of the hazard. Accomplishment of this step means arriving at an agreement in a multi-party setting.

The seven categories of hazards are as follows⁹:

• Natural
• Structural/Mechanical
• Electrical (Powerlines are an electrical hazard)
• Chemical
• Radiant
• Biological
• Automated Systems

⁹ The textbook Construction Safety Engineering Principles (MacCollum, 2007) includes numerous subtopic classifications of hazards for each category.

Principle Four

Use the Engineers’ Safe Design Hierarchy to physically control hazards: It is not the role of the engineer (designer) to rely upon warnings and operating instructions as a substitute for the use of safety features. However, this sequence is also helpful in agreeing upon a path of efficient hazard elimination and designating responsibility in a multi-party setting. The following hierarchy of engineering control for hazards has become the accepted sequence for evaluating design for the prevention of hazards:

1. Elimination of the hazard (relocation of powerlines)
2. Guarding to prevent the hazard from causing harm (insulating link guards against electric shock)
3. Including safety factors to minimize the hazard (A range-limiting device to control boom movement within a safe envelope to disallow contact with a powerline brings the chance of powerline contact down to zero.)
4. Using redundancy for a group of parallel safeguards requires multiple levels to be breached before a harm-causing failure mode occurs. (Relocation or de-energization of powerlines, along with use of an insulating link to guard, proximity alarm to warn, and use of a range limiting device provides redundancy to the degree that it is virtually impossible to accidentally contact a powerline.)

Principle Five

Control the hazard with the appropriate design improvement or safety appliance: Once a hazard has been identified, categorized, and a correct procedure for control established, it is easy to design out the hazard before it can cause harm. A “Hazard Identification and Prevention Matrix,” pictured in Illustration 29, is used to assist the design engineer in determining the necessary safeguards. The matrix will provide a worksheet for the engineer, architect, owner, sub-contractors, rental agencies, and other involved parties to couple hazards with design controls. It is the first step to visualizing hazard control measures, as the matrix provides an immediate connection between a given hazard and its necessary control. Rounding out the process of elimination of hazards by design, completion of the matrix forces collaborating parties to examine different methods of hazard elimination. Discussion of these matrices allows the group to settle on the most efficient, cost effective method of hazard control and designates responsibility of execution.

Illustration 29