changes in codes standards and practices following crane failures

8/13/2019 Changes in Codes Standards and Practices Following Crane Failures

1/4November 201320

updates and discussionsrelated to codes and standards

CODESANDSTANDARDS

By Lawrence K. Shapiro, P.E. andRobert T. Ratay, Ph.D., P.E.

Part 3 Cranes

Changes in Codes, Standardsand Practices FollowingCrane Failures

This is Part 3 of a series of articles intro-ducing illustrative examples of changesin design and construction codes, stan-dards, regulations and practices that

have followed catastrophic failures of constructioncranes. Part 1, in the December 2010 issue ofSTRUCTURE, focused on bridges, Part 2 inthe April 2011 issue focused on buildings, andPart 3 is devoted to construction cranes.

It is a credit to our structural and construc-tion engineering professions that failures havebeen and continue to be used to improve design,construction and regulatory practices. We do not

just pay up, rebuild and walk away we delve,we learn, and we improve.A crane accident in the core of a large city canbe a dramatic event that splashes across televisionscreens and tabloid covers (Figure 1). Governmentofficials are compelled by public outcry to react;their constituents must be made to feel safe while

walking through streets stalked by the shadows ofgiant construction

cranes. Under suchcircumstances,major accidentsin dense urbanzones have spurredthe creation ofcrane regulations,particularly in

California, New York City and the UK. Officialsin other localities have reacted similarly to singu-lar dramatic accidents, sometimes creating lawsthat are closely crafted to the particularities ofthe accidents that spawned them.

is jagged path to the making of crane rules isan aberration. e great bulk of crane standardsand regulations in both the United States (US)and the world at large are, instead, the product ofa steady progression of deliberations, built uponcollective knowledge and wisdom acquired overdecades. Much of the knowledge, unfortunately,comes from the experience of accidents.

Most crane accidents do not occur in the centerof major cities, nor do they make the front pagesof tabloids. Tese lesser-publicized events add upto a much greater human and economic toll thanthe headline-grabbers. ey do not, however,escape attention. Stakeholders, who suffer thelosses and deal with the consequences, do notordinarily forget them (Figure 2). For those aptto learn from experience, the cruel lessons ofa serious mishap will be internalized, analyzedand applied.ere are also many incidents that might be

termed near-misses or minor mishaps. esefrightening brushes with catastrophe can bemoments of serendipity for those inclined to learnfrom them. For the small fraternity of participantsin standards-writing committees, hard-learnedlessons from failures in the field become oppor-tunities to contribute to the advancement ofindustrial codes.

Figure 1: On the Upper East Side of Manhattan, a towercrane collapsed during a climbing operation, resulting inmultiple deaths and massive property damage.

Figure 2: A half-mile-long cableway across Black Canyon on the Colorado River collapsed during high winds. Itsloss set back construction of a vital interstate bridge link by two years.


2/4STRUCTURE magazine November 201321

Crane Uses and Their Hazards

Cranes are broadly classified into the categoriesof Industrial, Construction and Marine. Somecrane and rigging rules overlap in covering allthree, while others are particular. For example,the American Society of Mechanical Engineers

ASME B30.20: Below-the-Hook Lifting Devicescovers lifting accessories for all cranes, while

ASME B30.3: Construction Tower Cranes istargeted for its construction specificity.Industrial cranes usually operate in well-

controlled settings, with operations that arerepetitive and equipment that is often fixedin place or operating in circumscribed zones.Some common crane types in general industryare stackers, loaders, bridges and gantries.

Accidents mostly occur from complacency,lack of training, inadequate supervision ordeficient maintenance. (ese causes couldalso serve to explain a great many industrialaccidents outside of the crane and rigging

sphere.) After all, cranes are subjected to abuseand prone to failure just like other mechanicalcontrivances used by general industry.Te things that cause most accidents in gen-

eral industry can cause construction craneaccidents as well, but construction sites intro-duce additional hazards. Site conditions areshort-lived and ever-changing; personnelrotate through, and the operations of thevarious trades overlap. Mobile cranes andtower cranes, the types most common onconstruction sites, each engender a distinctiveset of hazards that are unique to their class.

Teir users require specialized knowledge andprocedures that are additional to the generalset of rules for cranes and rigging.An informative discussion of the types,installation, operation and safety issues of con-struction cranes is in Chapter 20, Cranes,by L. K. Shapiro, in Temporary Structures inConstruction,3rdedition, R. T. Ratay, Editor,McGraw-Hill, Inc., 2010.e special nature of crane hazards on

construction sites demands that particu-lar rules exist for that milieu. at is why,for example, the Occupational Safety andHealth Administration (OSHA) maintainsan extensive section about cranes under itsconstruction standard (29 CFR 1926 SubpartCC: Cranes and Derricks in Construction)that is separate from its standards for gen-eral industry.

US Crane Standards

Out of professional considerations, as wellas from long-term self-interest, stakeholdershave often organized to produce codes forthe safe design and operation of cranes. Such

voluntary efforts long predate governmentregulation. e collective wisdom of manyexperts gathering year-after-year has producedsome well-known and widely-utilized seriesof rules, particularly the B30 series spon-sored by the American Society of MechanicalEngineers (ASME). Important US standardsare also produced under the tutelage of the

American Petroleum Institute (API) and theSociety of Automotive Engineers (SAE).Tese rules are considered consensus standards.

ough lacking legal clout, their authorityarises from the broad expertise of those who

write them, and from the dedication of thesponsoring organizations to promote for thepublic interest. It is widely understood, butrarely stated, that sound standards are not

just for the broad public good, but conferdirect benefits to individual stakeholders. Bypromoting best practices they improve safety,and by promoting consistency of practices

they remove a large measure of uncertaintyfrom the industrial milieu.ough consensus codes and standards do

not have the force of law, they oftentimesare incorporated into laws or are treated asde facto laws by regulatory and enforcementauthorities. ey are frequently cited in civillitigation and thus are well-entrenched in thecommon law.e list of stakeholders in the crane and

rigging industry is long. A crane in serviceusually has a manufacturer, an owner, a user,an operator in the seat, a tradesman, often aconstruction manager or general contractor,and a project owner. ere are also projectplanners, component manufacturers, engi-neers, safety professionals and regulators.Tough some have a more dominant presencethan others, all are represented at the tableduring codes and standards development.

Causes of Crane Accidents

in Construction

In the US, most medium-sized and large con-struction sites are serviced by mobile cranes.

eir variety, purposes and duration of usevary greatly. A truck-mounted mobile cranemay show up at a site to make a handful ofpicks before departing, while a crawler cranecould be set up for a year-long assignment.Mobility confers its own set of hazards, infer-ring likelihood that an operating site has notbeen adequately surveyed beforehand andperhaps not prepared for the presence of a

crane. Moreover, the operator and crew maybe encountering unfamiliar conditions withunexplored hazards. Mobility also confers thepossibility of last-minute changes or improvi-sations, defeating the benefit of a plan.Among mobile cranes, the frequent types ofserious accidents are:

Electrocution the victims is usuallya rigger handling the load when theboom or load line contacts an overheadpower line.

Overturning caused by overloading,ground support failure or improper

operation of the crane (Figure 3). Collision a portion the crane or asuspended load strikes a building,person or object, or a suspended loadis trapped.

Over-travel the load block strikesthe boom tip or boom runs up againstthe backstops.

Structural failure from excessiveside loading, overloading or anequipment deficiency.

Assembly/disassembly failure the crewdeviates from a qualified procedure.

Crushing a worker is caught bya rotating or moving part such as arevolving deck or a spooling rope.

e same types of accidents can occur withtower cranes, albeit less frequently becausetower cranes tend to work under more con-trolled circumstances than mobile cranes.Tower cranes are used in the US primarilyon major construction sites. By nature, theyare fixed or semi-fixed in place and, there-fore, less prone to problems caused by scantyplanning, hasty preparation or last-minuteimprovisation. Te greatest exposure of thesemachines to accidents occurs when they arebeing erected, dismantled or jumped.

Crane Failures,

Codes and Standards

Tough code and standard are words thatare sometimes used interchangeably, the firstimplies a mandate while the latter is moreoften voluntary. e history of crane stan-dards in the US is longer than that of codes,beginning with the first ASME issuance in1916. Earlier standards, promulgated by the

Figure 3: A crawler crane relies on firm levelground support to keep it from tipping.



industry policing itself, focused on cranedesign and work practices. e same subjectmatter has evolved over the decades and canbe found in contemporary standards, but newtopics have been added. Recent developmentshave focused on personal responsibilities andqualifications, as well as requirements fordevices to enhance safety. Tese changes haveoften been in response to catastrophic failures.

Early government regulation of the craneand rigging industries was light, mostly occur-ring at the state level. e most significantdevelopment in the regulatory landscape tookplace when the OSHA act of 1970 was signedinto law. With that pen stroke, the federalgovernment became the dominant regulatorof crane and rigging practices.OSHA regulations lagged behind industry

standards until 2010, when a broad update ofOSHA construction crane regulations wentinto effect. Up until then, OSHA filled in thegaps by enforcing consensus standards as the

de facto law. e 2010 regulations absorbedmuch from these consensus standards, butalso moved beyond them. In developing thenew regulations, OSHA consulted with apanel of industry experts and applied cost-benefit analyses in addition to unalloyedsafety considerations. ough portions ofthe regulations remain controversial in theindustry, the agency clearly based its work ona broad view without reacting knee-jerk toparticular events of failures.In spite of the new robust OSHA crane rules,

localities that have their own regulations are

unlikely to back away from them. e mostentrenched of these rules in New York City,Chicago and California are justified by offi-cials as being necessary to provide an extralayer of protection for the citizenry in denselypopulated urban spaces.Some of the background for these rules

is instructive, as described in the followingexamples of crane failures that precipitatedchanges in codes, standards and practices.

Illustrative Cases

New York City 1985 East 63rdStreetMobile Crane Overturns Ontoa Pedestrian

Since 1968, New York City has had the mostcomprehensive crane laws in the country,requiring engineering certification and Cityapproval of models, registration and inspec-tion of individual machines, and professionalengineering design for field installations.Notwithstanding these requirements, seriousfailures have occurred, some of them spurringrevisions to the existing regulations.

In May 1985, during the early phase ofconstruction of a residential high-rise build-ing, a 35-ton telescopic crane turned overonto a passerby, pinning her precariouslybetween the crane and the foundation wall(Figure 4). Te ensuing dramatic rescue ofthe woman, who had been walking by thesite on an open public sidewalk, broughtnational attention including a television

movie and a presidential bedside call.Investigators determined that the cranehad been operated by a laborer who hadhastily jumped in the operators vacant seatto unload a truckload of rebar that hadarrived during lunch break. In the haste tocomplete the task before the regular opera-tors return, he had failed to extend theoutriggers fully. When the boom swungover the side of the crane with the load onthe hook, it toppled towards the site.e incident prompted city officials to

strengthen administrative rules both for

cranes and for general site safety, and a newsite safety enforcement unit was created withinthe Department of Buildings. New administra-tive rules required on-site inspection of eachcrane by a professional engineer prior to itsoperation, assignment of a person to be respon-sible for safe crane operation and certification

of site safety managers. In ensuing years, thesemeasures have been greatly expanded.

San Francisco 1989 Tower Crane Collapse

In November 1989, a 350-foot tall towercrane constructing a downtown San Franciscohigh-rise office building collapsed whileengaged in a climb. Five people were killed,including two passers-by. With a mangled

wreckage and key witnesses among the dead,the cause was not easily discerned. However,investigators eventually determined that theupper part of the crane had been rotatedduring a critical stage of the climb. e actof rotation threw the crane out of balanceand loaded the climbing apparatus above itsultimate capacity.As a result of this catastrophic failure, theCalifornia state legislature turned its atten-tion to tower cranes, which had previouslybeen given scant regulatory scrutiny at thestate level. Labor Code Sections 7375-7384,

that followed the 1989 incident, enableda strict regimen of inspections, the moststringent in the country. Some of theseinspections are now performed by state-certified private inspectors and others byCal/OSHA. A qualified inspector is alsorequired to be present during climbs and

when dismantling a tower crane.Though tower crane inspection rules

have toughened around the country, noneapproach the stringency of California exceptperhaps for New York City.

Bellevue, WA 2006 Tower Crane Collapse

On a November night, a 210-foot-tallfreestanding tower crane constructing ahigh-rise building toppled onto severaladjoining buildings, killing one occu-pant (Figure 5). e project had beenredesigned and recently restarted after an

Figure 4: Telescopic crane toppled into aconstruction site, pinning a passerby.

Figure 5: A tower crane toppled after its base frame failed.



earlier abandonment. With the old towercrane footing not in a suitable location, anew base support had been established on afabricated steel frame attached to columnsand shear walls in the underground garage.Due to a serious communication gap, the

base designer was working with assumptionsthat differed drastically from the actual con-ditions on the site. e base designer usedloads provided by the crane supplier andrelayed by the general contractor, with theclear understanding that the crane would beerected with a tie connecting its mast to the

building core, such that there would be nooverturning moment on the base. However,the general contractor erected the craneinitially as freestanding with no tie, thusimposing significant overturning momentson the base that far exceeded its capacity.Triggered by this failure, two crane-safety

bills were introduced in the Washington statelegislature: Senate Bill 5990 and House Bill2171, signed into law in 2007, making thestates new crane safety regulations among thenations strictest. Effective January 1, 2010,the Crane Safety Act requires, among other

things, cranes to be load-tested, inspected,and certified at least annually, after any sig-nificant modification or repair of structuralparts, and before and after each setup at anew site. It also requires crane owners to havean independent professional engineer reviewand approve plans for any non-standard towercrane base.

New York City 2012 Crane BoomFailure during Superstorm Sandy

In October 2012, a high-profile failureoccurred after the final stages of erecting a

90-floor residential building in mid-townManhattan. At the height of Superstorm Sandy,the boom flipped backwards and hung men-acingly until it was secured several days later(Figure 6). e failure drew public attentionfor the spectacle high above the streets. Amongengineers and regulators, it left questions con-cerning the adequacy of existing practices forleaving tower cranes to weathervane in high

winds. e incident is still under review andis likely to spur new regulations.

Closure

In the not-too-distant past, a crane accidentwas treated primarily as an economic loss.e economic impact has not diminishedfrom times past, but the social cost hasincreased. Society is much less tolerant ofaccidents and more inclined to assign blame.Te calculus of risk management has shiftedaway from being a mere actuarial exercise;

the stigma following a failure can seriouslydamage a company or a career, including thepossibility of criminal prosecution. Beyondall these, injury or loss of life results in

wrenching human suffering.Crane accidents will always occur, as humans,

materials and machines are imperfect, hazardsare sometimes hidden, and nature is fickle.Te burden of our profession and our industryis to learn from things that go wrong, developcorrective means and strategies and applythem. Laws and standards are merely one setof means to mitigate.

Lawrence K. Shapiro, P.E., is a principalof Howard I. Shapiro &AssociatesConsulting Engineers in New York, with a

practice centered on cranes and other meansof construction. He is coauthor of Cranes&Derricks, 4thEdition, and a memberof several international and US code-writing committees. He can be reached [email protected].

Robert T. Ratay, Ph.D., P.E., i s astructural engineer in private practice in

New York, and an Adjunct Professor atColumbia University. He has been anexpert consultant/witness on some 200cases of structural failures, some of whichresulted in changes to codes, regulationsand practices. He is the Editor-in-Chiefof three books: Handbook of TemporaryStructures in Construction, 3rdEdition,Forensic Structural Engineering, 2ndEdition, and Structural Condition

Assessment. He can be reached [email protected]

Figure 6: A tower crane boom flipped backwardsduring Hurricane Sandy, dangling above the streetsof Manhattan.

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