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Preventing Falls from Heightsthrough the Design ofEmbedded Safety Features

Description ofExposureConstruction is one o the most danger-ous industries [oole and Gambatese2008], and alls are a requent cause oatal injuries in this industry. O the4,693 atal work injuries that occurredin 2011, 553 (12%) were the result oalls to a lower level. Fatal alls in con-struction accounted or 46% o all work-related atal alls in 2011 [BLS 2012].OSHA estimates that each all rom

an elevated position in construction(both atal and nonatal) costs between$50,000 and $106,000 [OSHA 2012].Workers are at risk o alling during ini-tial construction, and afer completionduring operation, maintenance, renova-tion, and demolition o buildings. Facil-ity eatures associated with alls includefloor and roo edges, elevated platorms,ledges, atria, skylights, machine rooms,and ladders and stairways. Falls can oc-cur rom temporary structures used inconstruction and maintenance such asscaffolds or ladders, or rom permanentlocations such as roos.

StandardsOSHA Standard 29 CFR*1926.502 cov-ers requirements or all protectionsystems. One o the ollowing is alwaysneeded to protect workers rom alls:

Job-built or commercially availableguardrails that meet OSHA heightand strength requirements [29 CFR1926.502(b); Bobick et al. 2010].

Properly designed anchor points withappropriate personal all arrest sys-

tems and lielines [Bobick et al. 2010].

Other orms o all protection such assaety netting [29 CFR 1926.502(c)].

Te American National Standards In-stitute (ANSI) Standards [2007] ANSIZ359.0 through Z359.18 describe saetyrequirements or all arrest systems.ANSI Standard Z590.3 addresses preven-tion through design guidelines or haz-ards in the design and redesign processes.

*Code of Federal Regulations. See CFR inReerences.

Prevention throughDesign (PtD)

PtD addresses worker exposure to haz-ards during the design stages o a project.For example, when a building or otherstructure is designed or redesigned, riskso all-related injuries and atalities toconstruction workers and users o thecompleted acilities could be minimizedby ollowing a PtD approach. NIOSHrecommends that acility designers, own-ers, constructors, and saety and healthproessionals collaborate to perorm oneor more saety design reviews to explore

and address hazards likely to occur overthe lie cycle o the acility.

Tis approach would incorporate saetyeatures into the buildings design, addressall hazards in construction plans, estab-lish saety criteria or buying equipment,and communicate risks to building own-ers and acilities personnel [Behm 2005]rather than rely on other orms o protec-tion such as personal protective equip-ment (PPE) or administrative controls.

Contents

Description o Exposure

Standards

Design Solutions

Cost Savings/Advantages oPermanent Features

Case Study

Recommendations

Acknowledgments

ReerencesDEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

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Design SolutionsDesigners should first consider the need or

permanent all protection eatures to protectconstruction workers, uture occupants o

acilities, and repair workers rom all haz-ards. A saety design review can help evalu-ate tasks that expose workers to hazards.

Designers and saety and health proession-als can then use the hierarchy o controlsto select the most appropriate options toaddress the identified risks [Gambatese et al.2005]. Te hierarchy o controls or all pro-tection involves the ollowing:

1. Eliminating or modiying the all hazarditsel is the preerred approach:

a. Adopting a building design involving

a single level at grade rather than mul-tiple levels at elevations would be thebest way to eliminate the all hazard.

b. Using parapet walls or permanent guard-

rails to separate the worker rom the allhazards would be the next preerred ap-proach to eliminating the all hazard.

2. Te second option is providing a all re-straint system that secures the worker via

an anchor point, connector, lanyard, andbody harness to prevent the worker romreaching the all hazard is the next option.

3. Installing a all arrest system: this finaloption also uses an anchor point, connec-

tors, lanyards, and body harnesses, butallows exposure to the all and is then de-signed to stop the all afer it has begun.

Installing permanent all protection ea-

tures, depending on when they are installedduring the construction process, may alsobe used to provide all protection to work-ers during the construction phase.

A common requirement or all all protec-tion is the provision o suitably designedand installed anchor and support locations,which include a secure connecting point ora terminating component o a all protectionsystem or rescue system capable o saely

supporting the impact orces applied by aall protection system or anchorage subsys-tem [ANSI/ASSE 2011]. For many typeso commercial and institutional buildings,equipment could be permanently embeddedinto steel or concrete parts o a building and

used to set up all protection systems.

Tese embedded saety eatures could be used

to prevent alls during construction and build-

ing maintenance afer construction. Embed-ded eatures can include concrete straps, an-

chor points or use with appropriate personal

all arrest systems and lielines, or guardrailsupport [See NIOSH 2013 or details, dia-

grams, and photos o various design eatures].

emporary saety eatures are not part o the

building when it is completed. Permanenteatures are part o the building when it is

completed. Planning or installation o per-

manent eatures is the preerred approach

and involves the architect and consulting en-gineers who design the building. Te eatures

provide protection or construction workers,

operations and maintenance workers, and u-ture construction workers doing renovation,

reurbishment, disassembly, or modification.

Te decision to include temporary eatures

is made by the construction companys en-gineers and saety personnel. Tese provide

benefits or the construction worker and are

typically removed when construction is done.OSHA general construction regulations [29

CFR 1926 subpart M] state that all protection

is required at 6 eet or temporary or construc-tion purposes. Different industries have other

protective height requirements, and they canbe ound in the appropriate OSHA regulation.

Embeds for guardrail support

Steel embeds could be placed along concrete

slabs so that guardrails could be installed atthe edges o all floors during construction.

Embeds provide a secure method o install-

ing guardrails that is quicker to install com-pared with bolted guardrail systems. Embeds

could be used or both temporary systems

used during construction, or or permanent

guardrail or parapet systems used or bothconstruction, operations and maintenance,

and other uture lie-cycle needs.

Embedded roof anchor points

Anchor points are needed when a personal

all restraint or personal all arrest system

is selected or all protection. Several em-bedded anchor points can be installed so

that they provide tie off points or attach-

ing horizontal or vertical lielines used or

these systems. Tey should be independento anchorage used to support or suspendplatorms and capable o supporting at least5,000 pounds [29 CFR 1926.502(d)(15)].

Straps embedded in concrete

Straps are installed beore casting by attach-ing each strap to the reinorcement (e.g. steelrebar) that will be buried within a concretecolumn, beam, or slab. Te other end o thestrap and its connecting D-ring are lef hang-ing, allowing workers to attach their personalall protection harnesses or other personalsaety equipment to the strap. D-rings andsnap hooks must be able to support a 5,000pound load [29 CFR 1926.502(d)(3) and 29

CFR 1926.502(d)(9)]. Straps should meetrequirements or ANSI Standard Z359.1. Testraps are typically removed afer construc-tion is finished, so this option is intended toprovide temporary all protection anchorageor construction workers.

Te decision to add concrete embeds shouldbe made during the conceptual design oa building. Only a minimal amount o ad-ditional design would be needed [NIOSH2013]. Research is being conducted on thesaety o new, environmentally riendly U.S.

Green Building Council Leadership in Ener-gy and Environmental Design (LEED) certi-fied buildings, and recommendations havebeen proposed to include PtD saety eaturesin these new designs. Including provisionsduring building construction to preventinjuries, illnesses, and atalities among con-struction workers is an essential componento sustainable design [Harte 2009].

Cost Savings/

Advantages ofPermanent FeaturesAccording to OSHA regulations, employersare the entities responsible or worker saety.Perhaps or this reason, architects and designengineers do not always consider hazardsduring the design phase o a constructionproject. It is also possible that building de-signers are wary o assuming responsibilityor uture saety incidents, however there isno research to suggest that building design-ers who consider saety are more subject to

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lawsuits than those who do not. Designers

may also perceive that saety eatures take

more time and money to install; designs

are meant to be completed on schedule and

cost effective or the owner [Gambatese et

al. 1997; Gambatese et al. 2005; oole andGambatese 2008]. But having the all saety

eatures in the original design and perma-

nently embedded in concrete has been shown

to save money. Fall protection can be set up

more efficiently using permanently installed

eatures rather than the added costs associ-

ated with installing temporary all protection

each time there is a roo-related maintenance

or renovation task [Gambatese et al. 1997]. As

noted by Rajendran and Gambatese [2013],

roo anchor points are generally low cost.

Case StudyTe NIOSH Fatality Assessment and Con-

trol Evaluation (FACE) Program supports

atality investigation programs in several

States. Te ollowing case rom New Jersey

illustrates the importance o correct instal-

lation and how embedded anchors might

have prevented a all.

A 51-year-old construction worker died afer

alling rom the roo o an industrial ware-house under construction. He was wearing

ull protective equipment, including a har-

ness and retractable lanyard connected to a

temporary metal anchor installed as part o

the construction all protection system. Te

anchor was attached to the unsecured leading

edge o the corrugated decking. When the an-

chor broke ree, he ell 40 eet to the ground.

In addition to improper anchor plates and

screws, another contributing actor to the

all was having the anchor plate mounted on

an unsecured edge. I the anchor plate hadbeen an embedded eature that was part o a

permanent all protection system, the anchor

might not have broken ree and caused the

victim to all to the ground [NJ DOH 2012].

RecommendationsBuilding owners and designers should take

the ollowing measures to prevent alls

[NIOSH 2013; NYC DOB 2008; NJ Health

2012]:

During retrofits, renovations, or new

construction, perorm a saety design

review to identiy and consider tasks

that could involve all hazards over the

lie cycle o the acility. Use Prevention

through Design approaches to prevent

all hazards or to provide engineering

eatures to provide all protection.

Consult with certified proessional engi-

neers to install new eatures or to retrofit

older buildings with permanent embed-

ded saety eatures.

For new construction, an architect or

structural engineer should prepare a

drawing indicating the location o all

protection anchor points and their ca-pacities or guiding construction and

maintenance personnel.

Ensure that a competent person[29

CFR 1926.32()] inspects the all arrest

system beore and during installation.

Have any existing concrete-embedded

all arrest systems field tested by a quali-

fied testing entity to ensure that they are

capable o withstanding intended loads.

Ensure that a competent person inspectsand evaluates the all arrest systems regu-

larly or damage.

Ensure that no one uses the system

beore compliance with the conditions

listed above.

AcknowledgmentsTis document was prepared by E. A. McK-

enzie, Jr., Division o Saety Research, Matt

Gillen, Office o the Director, and SusanAanuh, Education and Inormation Divi-

sion, National Institute or Occupational

Saety and Health.

Competent person means one who iscapable o identiying existing and pre-dictable hazards in the surroundings orworking conditions that are unsanitary,hazardous, or dangerous to employ-ees, and who has authorization to takeprompt corrective measures to eliminatethem [29 CFR 1926.32()].

ReferencesANSI [2007]. Saety requirements or per-

sonal all arrest systems, subsystems, andcomponents. Standard Z359.1.

ANSI/ASSE [2011]. Prevention throughdesign guidelines or addressing occu-pational hazards and risks in design andredesign processes. Standard Z590.3.

Behm M [2005]. Linking constructionatalities to the design or constructionsaety concept. Saety Sci 43:589611.http://www.sciencedirect.com/science/ar-

ticle/pii/S0925753505000731.BLS [2012]. able A9. Fatal occupational

injuries by event or exposure or all atalinjuries and major private industry 1sector, all U.S., 2011. Washington, DC:

Bureau o Labor Statistics. http://www.bls.gov/ii/oshwc/coi/cfb0267.pd.

Bobick G, McKenzie, Jr, EA, Kau -Y[2010]. Evaluation o guardrail systemsor preventing alls through roo andfloor holes. J Saety Res 41: 203211.

CFR. Code o Federal regulations. Wash-ington, DC: U.S. Government PrintingOffice, Office o the Federal Register.

Gambatese JA, Hinze JW, Haas C [1997].ool to design or construction workersaety. J Arch EngMarch:3241.

Gambatese JA, Behm M, Hinze JW [2005].Viability o designing or constructionworker saety. J Constr Eng Manage Sep-tember:10291036. http://aculty.kupm.edu.sa/cem/jannadi/Viability-o-Designing-

or-Construction-Worker-Saety.pd.Harte A [2009]. Sae and green building

design. PtD in Motion Newsletter.July(5):910.

NJ DOH [2012]. Hispanic constructionworker wearing all protection dies aferalling 40 eet rom roo. renton, NJ:New Jersey Department o Health, Pub-

lic Health Services branch, Division oEpidemiology, Environmental and Oc-cupational Health, Occupational HealthSurveillance Unit. http://www.cdc.gov/niosh/ace/stateace/nj/09NJ099.html.

NYC DOB [2008]. Regulatory Notice: newprotocols or existing and new concrete-embedded all arresting systems. NewYork City Department o Buildings. http://www.nyc.gov/html/dob/downloads/pd/regu-

latory_all_arrest_061308.pd.NIOSH [2013]. Architectural design

and construction: instructors manual.

http://www.sciencedirect.com/science/article/pii/S0925753505000731http://www.sciencedirect.com/science/article/pii/S0925753505000731http://www.sciencedirect.com/science/article/pii/S0925753505000731http://www.bls.gov/iif/oshwc/cfoi/cftb0267.pdfhttp://www.bls.gov/iif/oshwc/cfoi/cftb0267.pdfhttp://faculty.kfupm.edu.sa/cem/jannadi/Viability-of-Designing-for-Construction-Worker-Safety.pdfhttp://faculty.kfupm.edu.sa/cem/jannadi/Viability-of-Designing-for-Construction-Worker-Safety.pdfhttp://faculty.kfupm.edu.sa/cem/jannadi/Viability-of-Designing-for-Construction-Worker-Safety.pdfhttp://www.cdc.gov/niosh/face/stateface/nj/09NJ099.htmlhttp://www.cdc.gov/niosh/face/stateface/nj/09NJ099.htmlhttp://www.cdc.gov/niosh/face/stateface/nj/09NJ099.htmlhttp://www.cdc.gov/niosh/face/stateface/nj/09NJ099.htmlhttp://www.nyc.gov/html/dob/downloads/pdf/regulatory_fall_arrest_061308.pdfhttp://www.nyc.gov/html/dob/downloads/pdf/regulatory_fall_arrest_061308.pdfhttp://www.nyc.gov/html/dob/downloads/pdf/regulatory_fall_arrest_061308.pdfhttp://www.nyc.gov/html/dob/downloads/pdf/regulatory_fall_arrest_061308.pdfhttp://www.nyc.gov/html/dob/downloads/pdf/regulatory_fall_arrest_061308.pdfhttp://www.nyc.gov/html/dob/downloads/pdf/regulatory_fall_arrest_061308.pdfhttp://www.nyc.gov/html/dob/downloads/pdf/regulatory_fall_arrest_061308.pdfhttp://www.cdc.gov/niosh/face/stateface/nj/09NJ099.htmlhttp://www.cdc.gov/niosh/face/stateface/nj/09NJ099.htmlhttp://faculty.kfupm.edu.sa/cem/jannadi/Viability-of-Designing-for-Construction-Worker-Safety.pdfhttp://faculty.kfupm.edu.sa/cem/jannadi/Viability-of-Designing-for-Construction-Worker-Safety.pdfhttp://faculty.kfupm.edu.sa/cem/jannadi/Viability-of-Designing-for-Construction-Worker-Safety.pdfhttp://www.bls.gov/iif/oshwc/cfoi/cftb0267.pdfhttp://www.bls.gov/iif/oshwc/cfoi/cftb0267.pdfhttp://www.sciencedirect.com/science/article/pii/S0925753505000731http://www.sciencedirect.com/science/article/pii/S0925753505000731

8/12/2019 2014-124

4/4

Cincinnati, OH: U.S. Department oHealth and Human Services, Centersor Disease Control and Prevention, Na-tional Institute or Occupational Saetyand Health. http://www.cdc.gov/niosh/

docs/2013-133.OSHA [2012]. Workers compensation

costs o alls in construction. Wash-ington, DC: U.S. Department o Labor,Occupational Saety and Health Admin-istration. http://www.osha.gov/dcsp/prod-ucts/topics/businesscase/costs.html.

Rajendran S, Gambatese JA [2013]. Riskand financial impacts o preventionthrough design solutions. Pract PeriodStruct Des Constr 18(1):6772.

oole M, Gambatese J [2008]. Te tra-jectories o Prevention through De-sign in construction. J Saety Research39:225230. http://www.cdc.gov/niosh/top-ics/ptd/pds/Toole.pd. CFR. Code o Fed-eral regulations. Washington, DC: U.S.Government Printing Office, Office othe Federal Register. http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_

id=10758&p_table=STANDARDS.Gambatese JA, Hinze JW, Haas C [1997].

ool to design or construction workersaety. J Arch EngMarch:3241.

Gambatese JA, Behm M, Hinze JW [2005].

Viability o designing or construction

worker saety. J Constr Eng Manage Sep-tember:10291036. http://aculty.kupm.edu.sa/cem/jannadi/Viability-o-Designing-

or-Construction-Worker-Saety.pd.Hsaio H, Simeonov P [2001]. Preventing

alls rom roos: a critical review. Ergo-nomics 44(5):537561.

ICC [2012]. International Building Code. In-ternational Code Council, Standard 714.1.

NIOSH [1997]. Project engineer dies in allrom roo in Massachusetts. Cincinnati,OH: U.S. Department o Health and Hu-man Services, Centers or Disease Controland Prevention, National Institute or Oc-cupational Saety and Health, MA FACE97MA04401. http://www.cdc.gov/niosh/ace/stateace/ma/97ma044.html.

NIOSH [2000]. Worker deaths by alls: asummary o surveillance findings andinvestigative case reports. By BraddeeRW, Hause MG, Pratt S. Cincinnati, OH:U.S. Department o Health and HumanServices, Centers or Disease Controland Prevention, National Institute orOccupational Saety and Health, DHHS(NIOSH) Publication No. 2000116.http://www.cdc.gov/niosh/docs/2000-116/

pds/2000-116.pd.NIOSH [2013]. Architectural design and

construction: instructors manual. Cin-

cinnati, OH: U.S. Department o Health

and Human Services, Centers or Dis-ease Control and Prevention, NationalInstitute or Occupational Saety andHealth, DHHS (NIOSH) PublicationNo. 2013133. http://www.cdc.gov/niosh/

docs/2013-133.OSHA [2012]. Workers compensation

costs o alls in construction. Wash-ington, DC: U.S. Department o Labor,Occupational Saety and Health Admin-istration. http://www.osha.gov/dcsp/prod-ucts/topics/businesscase/costs.html.

OSHA Alliance Program [2010]. Construc-tion workplace design solutions: speciysufficient wall height to allow parapets tounction as all prevention. OSHA Alli-ance Program Construction Roundtablehttp://www.designorconstructionsaety.org/

Documents/Parapets_rev9.doc.Pupkin A [2013]. Parapet roos. Ezine

Articles. August 15. http://ezinearticles.com/?Parapet-Roos&id=7937534.

Rajendran S, Gambatese JA [2013]. Riskand financial impacts o preventionthrough design solutions. Pract PeriodStruct Des Constr 18(1):6772.

oole M, Gambatese J [2008]. Te tra-jectories o Prevention through De-sign in construction. J Saety Research39:225230. http://www.cdc.gov/niosh/

topics/ptd/pds/Toole.pd.

For More Information

Te inormation in this document is based on research related to Preventionthrough Design (PtD) initiatives. More inormation about PtD is availableon the NIOSH website at http://www.cdc.gov/niosh/topics/PtD.

More inormation about all injury prevention can be ound at:

http://www.cdc.gov/niosh/topics/alls

More inormation about the NIOSH FACE Program can be ound on theNIOSH website at:

http://www.cdc.gov/niosh/ace Click hereor a list o NIOSH FACE Reports related to construction alls.

Click hereor a list o State FACE Reports related to construction alls. Click hereor a list o NIOSH FACE Reports related to PtD.

o obtain inormation about other occupational saety and health topics,contact NIOSH at:

elephone: 1800CDCINFO (18002324636)Y: 18882326348 CDC INFO: www.cdc.gov/ino

or visit the NIOSH website at www.cdc.gov/niosh

For a monthly update on news at NIOSH, subscribe to NIOSH eNewsbyvisiting www.cdc.gov/niosh/eNews.

Mention o any company or product does not constitute endorsement byNIOSH. In addition, citations to websites external to NIOSH do not consti-tute NIOSH endorsement o the sponsing organizations or their programsor products. Furthermore, NIOSH is not responsible or the content othese websites.

This document is in the public domain and may be freely

copied or reprinted. NIOSH encourages all readers of the

Workplace Design Solutionsto make them available to all

interested employers and workers.

As part o the Centers or Disease Control and Prevention, NIOSH is theFederal agency responsible or conducting research and making recommen-dations to prevent work-related illness and injuries.

May 2014 Publication No. 2014124

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