|Designing for Construction Worker Safety
By John W. Mroszczyk, Ph.D., P.E., CSP
The construction industry stands out from other employments as having one of the highest worker injury and fatality rates. Construction comprises a very small percentage of the overall workforce. Yet, the incidence rate for non-fatal injuries and illnesses exceeds that of many other industries. The construction industry has the most fatalities of any other industry sector (Bureau of Labor Statistics, 2004). Some studies have shown that a fairly large percentage of construction accidents could have been eliminated, reduced, or avoided by making better choices in the design and planning stages of a project (Hecker 2005). Addressing construction safety in the design and planning phase, therefore, can have a substantial impact on reducing injuries and the cost associated with safety related project delays.
The Contractors’ Role in Construction Site Safety
Construction safety (the intermediate phase between a finished design and a completed building) is largely the responsibility of the contractors and other site professionals. The success of a project depends on the intricate planning and decisions that are made on site. Most construction accidents result from basic root causes such as lack of proper training, deficient enforcement of safety, unsafe equipment, unsafe methods or sequencing, unsafe site conditions, not using the safety equipment that was provided, and a poor attitude towards safety (Toole, 2002). Often times the role of the various contractors is unclear as some contractors may try to transfer responsibility for safety to others. The most common construction project arrangement is that of general (prime) contractor/subcontractor.
Under OSHA 1926.16, the prime contractor has overall responsibility for job site safety (compliance with OSHA regulations). General (prime) contractors have the highest level of influence on site safety because they monitor, coordinate and direct the work of the subcontractors. General contractors frequently provide equipment that is shared by multiple subcontractors. There may be one or more prime contractors in come cases.
Subcontractors provide the labor and tools to complete their work. Under OSHA 1926.16, subcontractors are responsible for the safety of their employees with regard to their portion of the work. If a subcontractor creates a hazard, the subcontractor must protect its own employees as well as others who might be exposed.
The Role of Design Professionals in Influencing Construction Site Safety
The role of the design professional has traditionally been to design a building, facility, or structure such that it conforms with accepted engineering practices, local building codes, and is safe for the public. The safety of construction workers is left up to the contractors. However, design professionals can influence construction safety by making better choices in the design and planning stages of a project. This would result in fewer site decisions that have to be made by contractors and workers that can lead to accidents (the root causes previously mentioned).
Research presented by Behm (Behm 2005) suggests that designers can in fact have a strong influence on construction safety. In 1985 the International Labor Office recommended that designers give consideration to the safety of workers who will be involved in erecting buildings. In 1991 the European Foundation for the Improvement of Living and Working Conditions concluded that about 60% of fatal accidents in construction are the result of decisions made before the site work begins. In 1994 a study of the United Kingdom’s construction industry found a causal link between design decisions and safe construction.
Figure 1 Time/Safety Influence Curve (From Behm) The ability to influence safety
diminishes as schedule moves toward start-up.
Behm referenced work from Szymberski.. The ability to influence construction safety versus time is depicted in Figure 1. The ideal time to influence construction safety is during the concept and design phase. As the curve shows, the ability to influence safety diminishes as the schedule moves from concept toward start-up. Unfortunately, in the United States, safety is usually is not addressed until construction begins.
Perhaps the clearest example as to how design professionals can influence safety is in the design of a parapet wall. The International Building Code paragraph 704.11.1 requires that a parapet wall be at least 30 inches high. OSHA 1926 Subpart M requires a 42-inch guardrail or other fall protection when working at elevated heights. This means that if the parapet wall were designed to be between 30 inches and 42 inches, a temporary guardrail at a height of 42 inches or other fall protection would have to be used during construction and future roof maintenance. A decision would have to be made at the site concerning fall protection. This leaves open the possibility of a fall injury if inadequate fall protection is used, workers are not trained, or if fall protection not used at all. However, if the designer specifies a 42 inch high parapet wall, not only does the design complies with the building code (safe for the public), the risk of a fall injury during the lifetime of the structure is eliminated because fall protection would not be required.
Designing for Construction Worker Safety (DfCS)
Designing for Safety (DFS) is the formal process that incorporates hazard analysis at the beginning of a design (Hagan). This process starts with identifying the hazard(s). Engineering measures are then applied to eliminate the hazard(s) or reduce the risk. The hierarchy of design measures starts with eliminating the hazard(s) by engineering design. If the hazard(s) cannot be eliminated by engineering design, then safety device(s) are incorporated. If the risk of injury cannot be eliminated by engineering design, or reduced by incorporating a safety device, then warnings, instruction, and training are the last resort. This process has been applied to the design of products, equipment, machines, facilities, buildings, and job tasks. Manufacture, assembly, and maintenance are considered during the design process.
Designing for Construction Worker Safety (DfCS) is an extension of the DFS process to construction projects. The DfCS process applies to the design of a permanent building, facility, or structure. The process does not address methods to make construction safer, but how to make a project safer to build. For example, the use of fall protection systems is not part of the DfCS process. Where DfCS would come into play is to influence design decisions that could eliminate or significantly reduce the need for fall protection systems during construction and maintenance. It requires the ability to identify potential hazards associated with construction and maintenance workers in the design stage of a project. The skill of the design professional is then applied to eliminate the hazard (or significantly reduce the risk) by incorporating the appropriate design features.
The involvement of design professionals, specifically engineers, is not totally new to construction safety. Many of the OSHA construction regulations currently require an “engineer” or “engineering controls”. Subpart P (excavations), Subpart L (scaffolds), Subpart R (steel erection), Subpart N (cranes, derricks, hoists, elevators, and conveyors), Subpart Q (concrete and masonry construction), and Subpart M (fall protection) all make reference to engineering services. DfCS takes the skill of the design professional one step further. Rather than designing temporary structures and systems for construction, design expertise would be extended to include the safety aspects of permanent structures, including maintenance.
Establish design for
and operation perspective
Identify design for safety
Process and Tools
DESIGN KICKOFF DESIGN INTERNAL EXTERNAL ISSUE FOR
REVIEW REVIEW CONSTRUCTION
Trade contractor QC/QA Focused Safety
Review Owner Review
Figure 2 The DfCS Process. The process incorporates site safety knowledge into
Figure 2 depicts the typical DfCS process. The key feature of this process is the input of site safety knowledge into design decisions. A number of progress reviews would ensure that safety is considered throughout the design process. The end product, the design documents, would not look any different than they do now. The only difference is that the drawing and specifications would reflect a design that is safer to build and maintain. Table I is a sample listing of DfCS design details.
Table I DfCS Design Details (from Weinstein(2005), Gambatese (1997), Behm(2005))
1. Design prefab units that can be built on the Reduce worker exposure to falls and being
on the ground and erected in place struck by falling objects
2. Design underground utilities to be placed Eliminate safety hazards associated with
using trenchless technologies trenching
3. Allow adequate clearance between structure Overhead power lines are hazardous when
and power lines. operating cranes
4. Design 42” parapet walls Eliminate need for fall protection
5. Design permanent anchorage points Provide fall protection anchorage during
construction and future maintenance
6. Specify primers, sealers, and other coatings Reduce noxious fumes
that do not emit noxious fumes
7. Design permanent anchorage points in Provide fall protection anchorage for
residential roofs roofing contractors during future
8. Design cable type lifeline system Allows workers to hook onto the structure
for tower structures and move up and down during future
9. Design window sills to be 42 inches above Eliminate need for fall protection during
floor construction and future maintenance
Design permanent guardrails around Prevent workers from falling through skylights skylight
There are a number of design aids available to design professionals. The Construction Industry Institute has developed over 400 design suggestions that could be used by design professional. These design practices have been incorporated into a computer design toolbox that can be purchased from CII. Visit their website at http://www.construction-institute.org.
The Health and Safety Executive in the United Kingdom has developed several documents that aid designers in designing for safety. These documents are available at http://www.hse.gov.uk/construction/designers/index.htm. Safety professionals in Australia have created a tool called Construction Hazard Assessment Implication Review (CHAIR). Its goal is to identify risks in a design as soon as possible. Visit the CHAIR website at http://www.workcover.nsw.gov.au/Publications/OHS/SafetyGuides/chairsafetyindesigntool.htm.
Information can also be found at the the DfCS website www.designforconstructionsafety.org.
OSHA Support for DfCS to Reduce Construction Workers Accidents
Designing for Construction Worker Safety (DfCS) is actively supported by DOL-OSHA’s Alliance Program through the Designing for Safety workshops being held in Washington, DC. The workshop participants include representatives of OSHA’s Office of Outreach Services and Alliances (OOSA), OSHA’s Office of Construction services, ASSE, ASCE, the Washington Group, the Construction Management Association of America, Belfor USA, the Independent Electrical Contractors, the Sealing, Waterproofing and Restoration Institute, the Laborers Health and Safety Fund of North America, the International Association of foundation Drilling, and the International Safety Equipment Association. A generic power-point DfCS has been developed and is available that can be modified to suite the needs of any organization. Both a 2 to 4 hour and 10-hour training course for design professionals is currently being developed. Contact Jess McCluer, email@example.com or LeeAnne Jillings, Jillings.LeeAnne@dol.gov for more information on the Design for Construction Safety workshops.
Designing for Construction Worker Safety (DfCS) is an extension of the DFS process to construction projects. The potential to reduce construction accidents by addressing construction safety in the design and planning phase is an incentive for moving forward with this concept.
Please plan to attend the Designing for Construction Worker Safety workshop, Session 750, at the 2006 ASSE PDC in Seattle.
Dr. Mroszczyk is the President of Northeast Consulting Engineers, Inc., a consulting engineering firm base in Danvers, Massachusetts. He is the former administrator of the Engineering Practice specialty and has been active in the Greater Boston Chapter of ASSE. He currently is the ASSE representative to the OSHA Design for Construction Worker Safety and Fall Protection Safety Workshops being held at DOL-OSHA in Washington, D.C.
Bennett, L. “Peer Review Analysis of Specialist Group Reports on Causes of Construction Accidents”. HSE Health and Safety Executive Research Report 218.
Behm, M. “Linking Construction Fatalities to the Design for Construction Safety Concept” Safety Science 43 (2005) 589-611.
Bureau of Labor Statistics, U.S. Department of Labor, 2004.
Gambatese, J., Behm, M., and Hinze, J. “Viability of Designing for Construction Worker Safety”. Journal of Construction Engineering and Management. September 2005. pp. 1029-1036.
Gambatese, J., Hinze, J., and Haas, C. “Tool to Design for Construction Worker Safety”. Journal of Architectural Engineering, March 1997. pp. 32-41.
Hagan, P., Montgomery, J., and O’Reilly, J. Accident Prevention Manual for Business and Industry: Engineering and Technology, 12th Edition. National Safety Council: Itasca, IL, 2001.
Hecker, S., Gambatese, J., and Weinstein, M. “Designing for Worker Safety”, Professional Safety, September 2005, 32-44.
Hislop, R., “Who is Responsible for Construction Site Safety?”, Professional Safety, February 1998, pp. 26-28.
International Building Code 2003. International Code Council, Inc. Country Club Hills, IL.
Smallwood, J. “The Influence of Designers on Occupational Safety and Health”. First International Conference of CIB Working Commission W99. Lisbon, Portugal, 1996.
Toole, T., “Construction Site Safety Roles”, Journal of Construction Engineering and Management, May/June 2002, pp. 203-210.
Weinstein, M., Gambatese, J. and Hecker, S. “Can Design Improve Construction Safety: Assessing the Impact of a Collaborative Safety in Design Process”. Journal of Construction Engineering and Management October 2005 pp. 1125-1134