COMMITTED TO SAFETY AND VALUE ENGINEERING - SINCE 1985
Category

Scaffolding

Qualified Engineer Needed?

By | Blog, Scaffolding, Seismic Engineering | No Comments

Various standards and codes require that an engineer’s services are to be used for certain scaffold designs and installations.  Is that really necessary?  After all, thousands of scaffolds are constructed daily without any input from engineers.  Furthermore, do these engineers need to be qualified engineers or will any engineer be acceptable?  And even furthermore, aren’t scaffolds only to be designed by a qualified person.  And even more furthermore, doesn’t the U.S. federal Occupational Safety & Health Administration, OSHA, have one regulation that requires a “registered professional engineer” and other regulation that requires a “qualified engineer?”  Is there a difference?  Can you be a qualified engineer without being a professional engineer and can you be a professional engineer without being qualified?  The answer is yes, yes, yes and yes.

While OSHA requires that all scaffolds shall be designed by a qualified person, that is, an individual who has the ability to solve or resolve the issues at hand, certain scaffolds shall be designed by a registered professional engineer, while in other cases a “qualified engineer” is allowed.  That sounds confusing but it shouldn’t be.  To become a qualified registered professional engineer, an individual must meet the requirements set forth by the engineering profession.  First, an individual must hold a degree from a recognized accredited school—typically a college or university.  After successfully passing an 8-hour exam on the fundamentals of engineering, the candidate must then work under the supervision of a registered professional engineer for at least 4 years.  At that time, the candidate is allowed to take another 8-hour exam to verify that he/she is qualified to become a professional engineer.  The next step is for the professional engineer to apply for registration in the state or province in which he or she chooses to work.  Some states require additional examination before granting registration.  For example, California requires that the candidate pass an exam on seismic engineering.  Upon payment of a fee, in some states a substantial fee, the candidate is granted registration.  The registration is typically a 2-year registration; renewal in most states requires continuing education.  It is important to note that in addition to registration as a professional engineer, many states require a license to offer engineering services and of course a permit to conduct business in the state of registration.  Registration is indicated by the use of the initials P.E. in the U.S. and P.Eng. in Canada behind the engineer’s name.  Registration can be easily verified on state/provincial websites.

Registration as a “registered professional engineer” does not mean that you are qualified to design scaffolds.  Registered Professional Engineers must comply with the regulations of the state in which they are registered and also should comply with the ethics promulgated by the profession.  One of the tenets, and rules, is that engineers only practice within their field of expertise.  This means that not all registered professional engineers are qualified to design scaffolds.  Unfortunately, there are engineers who think they have the expertise but don’t.  Abuse of the title is often seen in the courtroom where supposed “experts” proclaim knowledge of scaffolding and regulations.  It appears the courts have allowed great latitude in the term “expert witness” to the consternation of qualified engineers. 

State and provincial boards monitor engineers’ activities and punish those who violate the rules.  The punishment ranges from letters of admonition to fines to license cancellation to imprisonment.  Interestingly, one can have a legitimate degree in a field of engineering but cannot offer engineering services without being a Professional Engineer.  In other words, unless you are registered, you cannot offer to provide engineering services.  Licensure is a serious controlled business.

Unfortunately, the term “engineer” had been diluted over time, to the frustration of the professional engineering community.  While railroad locomotive engineers are known to be a different type of engineer than discussed here, the term engineer is used in many other fields of endeavor, where it can create confusion.  While it is expected that professional engineers meet certain criteria regarding physics, material strength, structural analysis and other science fields, a “sales engineer” clearly is not a professional engineer.  Safety engineers do not meet the normal criteria for a professional engineer.  Custodial engineers and software engineers are other examples. 

What does a qualified engineer provide that a qualified person cannot is a legitimate question that deserves an objective answer. Qualified engineers can determine the strength of materials, components and structures to determine if a design is adequate for its intended purpose.  Engineers can evaluate existing situations for structural adequacy and compliance with applicable standards, regulations and industry practices.  In the case of scaffolding, the engineer must know the applicable regulations, the equipment being used in the design, and the impact the design will have on adjacent structures.  Depending on the scope of work, the engineer may also be required to understand other aspects of the project, including contracts and scheduling.

  A qualified registered professional engineer can provide the assurance that a scaffold is correctly designed, will provide the expected functionality and, most importantly, will not collapse!  A qualified registered professional engineer can analyze situations and offer creative economical solutions.  There is no doubt that many scaffolds can be designed by a qualified person, that is an individual with the knowledge and expertise to solve or resolve the issues at hand.  However, there are instances when the situation requires the special advanced education and expertise of a qualified professional engineer.  If you don’t know what those circumstances are, your qualified registered professional engineer should be able to tell you.

Hanging Out

By | Blog, Resources, Scaffolding | No Comments

The suspension rope supporting a temporary platform is the single most important element of a suspended scaffold. You may not agree with this—too bad for you. What if the rope breaks? The platform can only go down and if you are at a considerable height, the result will be mostly unpleasant. Understanding this suggests that we should probably be sensitive to the condition of the rope to which we trust our lives.

What is a rope? A typical definition describes a rope as a cord that consists of twisted strands of material, such as hemp or wire. Of course, that begs the question of what cords and strands are. For that matter what is hemp? Can you smoke it? Perhaps not. How about this: a rope is a bunch of string or thread twisted together to make a bundle that can hold some weight. In the case of suspended scaffolds, the strings are normally wire although other materials such as hemp and polypropylene can be used, depending on the application.

Rope has been around just about forever. Evidence of rope’s use shows up in ancient Asia and Egypt. Wire ropes were invented about 1831 or so by Wilhelm Albert, a German involved with mining. He sought a solution to the very real problem of using chains where the failure of one link meant the failure of the whole chain. By twisting individual wires/strings into small bundles (strands) and then twisting the strands into a rope, (a big bundle), any defects are spread over more components, thus avoiding the problem of the weak link.

The industrial revolution encouraged rapid development of wire rope technology and the use of wire rope continued to increase. In 1841, John A. Roebling, designer and constructor of the Brooklyn Bridge, began manufacturing wire rope in America. Continued research and development discovered that more wires in the rope offered more flexibility and in 1884, researcher Tom Seale developed the parallel strand, where he used different diameter strands to make the rope. Figure 1 illustrates the Seale design.

While iron wire was initially used for metal ropes, steel wire began to be used in the late 1800’s. In fact, steel wire rope was first used in the construction of the Brooklyn Bridge in New York; the main ropes are still in use, demonstrating the durability and longevity of wire ropes. Over time, other wire rope designs have appeared, including the Filler strand, the Warrington strand and the Lang lay rope. Each design has its advantages and the job requirements will dictate the choice.

Wire rope is strong stuff, especially considering its relative light weight. Wire rope load capacity is governed by the rope material, configuration and diameter. While wire rope is available in an almost infinite number of diameters, normal diameters for suspended scaffolds are 5/16 or 3/8 inches. By its nature, rope can only handle tensile loads (you can’t push a rope!). However, the great advantage of a rope is that it can still handle the rated load whether the rope is 5 feet or 500 feet long. Within limits, that means the rope can hang down a 300-foot tall building and still support the same load as the rope will on a 50-foot tall building.

Adjustable suspended scaffolds typically use drum hoists or traction hoists. Drum hoists wind the wire rope on a drum or spool attached to the scaffold platform while a traction hoist passes the rope through the machine. Consequently, a drum hoist and rigging must support the weight of the wire rope while a traction hoist does not.
As with all materials, wire rope, while rather durable, can be damaged by improper handling and use and can also just wear out through continued use. Consequently, suspended scaffold erectors, and users, must be adequately trained in the potential hazards. For example, erectors must know how to handle the wire rope, including how to pay out the rope and how to wind it back up at the end of the job. The rope must be installed so the bottom end of the rope can hang free.

The attachment of the rope to its anchor is obviously critical to the strength of the suspension system. At a minimum, when loops in a rope are being made, a thimble and three fist grips (no u-bolts please) must be used, spaced at the manufacturer’s recommendations. The bolts must be tightened in compliance with the manufacturer’s recommendations; they must be re-tightened after the first loading of the suspension system, and then typically every day after that. The entire scaffold system including the suspension rope, must be inspected prior to each workshift. Properly trained suspended scaffold operators will know to inspect the suspension wire ropes every time the platform is raised or lowered to ensure that the rope is still in useable condition. It is rather undesirable to get the rope stuck in the traction hoist when 100 feet in the air. Even less desirable is having the suspension rope break when 100 feet in the air!

Suspended scaffolds get some impressive media coverage when failures occur since the incident leaves workers dangling high above the street below. Reporters nervously describe the precarious (and assume a dangerous) situation, leading the uninformed observer to believe that these devices are incredibly unsafe and a peril to the users. Since wire ropes on properly designed scaffolds can support six times the expected load, when the scaffold fails, it isn’t because the equipment is hazardous, but rather it is because somebody just plain screwed up. Don’t you be one of them!

Can Scaffolds Support This?

By | Blog, Resources, Scaffold Bracing, Scaffold Components, Scaffolding | No Comments

Spring is in the air, the birds are chirping and scaffolds are being built. Can life get any better? It used to be that contractors feared winter in the northern regions of North America. Cold temperatures, snow, wind and generally miserable conditions prompted owners and contractors to curtail outdoor activities. That was then; now construction charges ahead, fearless and courageous against even the nastiest of weather. Once again science and progress has prevailed! Improved, clothing, materials, equipment and methods allow construction to continue in any environment.

 To facilitate these activities, it was common to enclose supported scaffolds against the weather. But times have changed; cold weather isn’t the only reason to enclose scaffolds. Containment of debris, tools and workers are now common reasons to enclose scaffolds. Enclosures are also used to advertise, block the work activities from pedestrians and even hide the workers who might be gawking at the pedestrians. Enclosing supported scaffolds is now a year around activity in all areas of North America, on all types of projects in all types of conditions.

Unfortunately, workers have false perceptions concerning supported scaffolds that are enclosed, including the perception that the forces on enclosed scaffolds are not as severe in summer as they are in winter; the perception that using open netting results in lower forces than using solid material; that no additional measures must be taken when a scaffold is enclosed and; site conditions have little effect on an enclosed scaffold.

The truth of the matter is that all scaffolds must be designed by a qualified person, that is, someone who can demonstrate the ability to properly design a scaffold, whether it is enclosed or not. Since designing for wind forces is a necessarily complicated matter, it is common that the qualified person for this design work is a Professional Engineer qualified in such activities. Of course, anyone can take a shot at the design (and unfortunately it is often the case), but the results can be fatal due to a gross underestimation of the forces developed by the wind. So, what is so complicated about wind design? Here are a few factors that must be considered:

Wind Forces

It is absolutely true that the force applied to a scaffold and its enclosure from the wind can be calculated. Short of a meteor falling out of the sky, there is no such thing as a “freak act of nature.” Those who argue so because their scaffold fell over need to be retrained. More accurately, an enclosed scaffold can be designed for a certain maximum wind speed; if the wind is expected to be higher than the design speed, either the scaffold must be dismantled, the enclosure removed, or additional measures must be taken to ensure the stability of the scaffold.

Wind Speed

Obviously, the wind velocity (speed) is the main factor in determining wind forces on a scaffold. However, choosing the correct wind speed for a specific location isn’t that easy. Although wind charts have been developed for North America that indicate maximum design wind velocities, choosing the correct velocity is just the starting point. In fact, there are numerous areas of the continent that have “special wind regions” that require additional investigation to determine the expected wind velocity. One example is along the east side of the Rocky Mountain range, extending from Montana down through Colorado and into New Mexico. At certain times of the year, Chinook winds, that is winds that drop down the east slopes of the mountains, reach as high as 100 mph. Similar winds, called the Santa Ana winds, occur in southern California. These winds don’t occur throughout the year; if your enclosed scaffold is erected during the right time of the year you don’t have to design for these winds; but watch out if the job is delayed and the scaffold is still standing when a Chinook wind hits!

Stability Ties

The key to scaffold success is to adequately design the scaffold and its connection to the adjacent structure. While U.S. federal OSHA and other agencies specify the minimum tie requirements for supported scaffolds, the tie spacing most likely will be grossly inadequate for any substantial enclosed scaffold. While #9 or #12 wire may suffice for a connection of an unenclosed scaffold, it typically is never adequate for an enclosed one. In other words, the ties for an enclosed scaffold must be designed for the anticipated tension and compression loads that are expected to occur. For those who choose to wing it and do something such as doubling up the ties should expect to see their scaffold take wing and fly like a kite. Keep in mind that it is not uncommon to have ties (and the adjacent structure) designed to hold several thousand pounds or more.

Adjustment Factors

When a qualified person designs an enclosed scaffold, he or she must consider these factors:

  • The height of the scaffold
  • The geographical location of the scaffold
  • The location of the scaffold relative to the surrounding structures
  • Surrounding Structures
  • Shape of the Scaffold/Structure (e.g. round or square)
  • Local Wind History
  • Partial or Full Enclosure
  • New construction or demolition
  • Existing structures—are the windows open or closed?

Time of year

This is not a complete list but it gives an idea of the potential complexity of the analysis and design.

Enclosure Porosity

Porosity is the fancy word for how many and how big are the holes in your enclosure material. If you are using netting, the holes can be quite small or they can be big. If the holes are over 2 inches in diameter, such as plastic fencing, porosity can be considered. Otherwise, the prudent scaffold designer will consider the netting as a solid material for the simple reason that the holes can become plugged. Snow and ice can easily plug the most porous netting in winter while sawdust, sand, asbestos (why you would use netting to try to contain asbestos is the more important question – you really need retraining!), stucco, plaster and other fine materials will also have an adverse effect on the airiness of your material regardless of the time of year.

While this article doesn’t cover all the factors that must be considered by the qualified person when designing an enclosed scaffold, it offers a glimpse into the complexity of the situation. Merely “doubling up the ties” and “this is the way I have always done it” is not a prudent approach; it just shows you are lucky. And while being lucky may work in craps or roulette, it has no place in the design of an enclosed supported scaffold. Is your life worth a throw of the dice?

Plank Criteria

By | Resources, Scaffolding, Scaffolding Platforms | No Comments

There are two criteria that predict the safety of a scaffold platform.  One of the criteria involves the engineering properties of the scaffold unit.  The other criterion addresses the correct installation of the platform.  Correct installation includes proper support, correct positioning to limit spaces between platform units, and the minimum width of the platform.

The Federal Occupational Safety and Health Administration, OSHA, and other agencies, set forth the minimum standards for the installation and use of platform units.  For example, regulations address the minimum and maximum overhang of platform units, the allowable deflection, the space between units, and the distance from the edge of the platform to the work surface and the guardrail system.  These regulations are in the subsection on platforms, 29CFR1926.451(b), and are quite specific.  The regulations address all platforms, including solid sawn wood plank, laminated veneer lumber (lvl), metal fabricated decks, and platforms constructed of structural members and sheathing such as plywood.  These specific regulations ensure that the platform you construct will stay on the scaffold, will be large enough so you won’t fall off the platform, and won’t have any openings that you may fall through.

Engineering properties also predict the safety of the platform.  For manufactured platforms, such as aluminum decks and laminated veneer lumber, the manufacturer indicates the capacity of the product.  For solid sawn plank, determining the capacity is not as straightforward due to varying factors.  These factors include the dimensions of the plank, the specie of tree, what part of the tree is being used, and if the wood has any damage.  How in the world do you determine if the plank is strong enough?  Fortunately, you have help!  Qualified engineers can determine the strength of the plank you are using if the dimensions, the specie of tree, and the quality of the wood are known.  The engineer will also need to know the span of the plank, that is, the distance between supports.  While you can give the engineer the dimensions and span of the plank, the type and quality of the wood is another story.  Unless you cut the tree down yourself, you probably won’t be able to tell if the wood is pine or poplar.  And unless you have learned how to grade lumber, you won’t know if the wood is any good.

How, then, is the grade of the wood determined?  Qualified, trained lumber graders are one method used by lumber mills to determine the strength of wood.  These individuals are trained to determine the various strengths of wood that will come from a tree.  Factors used to determine strength include such things as density (how many rings per inch), the straightness of the grain, and the frequency of knots.  Straighter grain, higher density, and fewer knots will result in a strong piece of wood.  On the other hand, frequent knots and low density will result in a low strength piece of wood.

The engineer relies on the ability of the grader to do his or her job correctly.  The engineer also relies on the accuracy of the stamp to determine precise information for you to use.  The bottom line here is that the information in the grade stamp dictates the accuracy of the engineer’s calculations.  Of course, this information will only be accurate if the plank you use has been graded by a qualified grader, using recognized standards.  If the wood is not as good as the grade stamp indicates disaster will surely follow.

For typical situations, it is recommended that only Scaffold Grade plank be used since this will enhance safety on your scaffold project.  Scaffold Grade plank is a very specific grade of lumber that has a very high strength compared to other commonly found lumber on a construction project.  However, if you choose to use a plank other than scaffold grade, it must be engineered for proper use.  This is the only way you will be safe and in compliance with the regulations.

Do not take chances with solid sawn wood plank.  A grade stamp from a recognized grading agency is your guarantee of accuracy.  High strength lumber is not cheap.  Neither is a worker’s life.  If the board breaks, there is no back-up.

Here Are Some Scaffolding Answers!

By | Resources, Scaffolding | No Comments

Here are answers to frequently asked (and some not so frequently asked) questions regarding scaffolding and related subjects:

Q: Do scaffold users have to have scaffold training.

A: Of course they do—why wouldn’t they? They need to be trained in fall protection, access, falling object protection, proper use, the scaffold load capacity, electrical hazards and proper handling of materials on the scaffold. [OSHA 29 CFR 1926.454(a)]

Q: Does a ladder have to stick 3 feet above the scaffold platform?

A: Only if it is a portable ladder. Purpose built attachable scaffold ladders do not although it is a good idea unless you have hand holds (such as the scaffolding) available.

Q: Does a portable ladder have to be tied at the top?

A: Not if it is sticking 3 feet above the platform.

Q: A supported scaffold ladder is straight up and down like a fixed ladder and clamped to the scaffold. Doesn’t that make it a fixed ladder?

A: Nope. It’s an attachable ladder purpose built for scaffolds. OSHA 29 CFR 1926, Subpart X – Stairways and Ladders does not apply. (Read the Subpart X Scope and Application)

Q: Do I have to always use scaffold grade plank on my scaffold?

A: Not if your scaffold has to comply with the Construction Industry OSHA standards. If you have to comply with the General Industry or Maritime standards, then the plank must be scaffold grade. Of course the SAIA recommends that you always use scaffold grade plank or equivalent.

Q: What’s a high wind?

A: That’s subjective. If you get blown off the scaffold, that is a high wind. It is up to the Competent Person to determine what a high wind is. I would take jobsite conditions and the work activity into consideration when determining if it is time to vacate the scaffold. 20 – 25 mph is a popular maximum wind speed for supported scaffolds although I have been on scaffolds in 50 mph breezes. [You don’t get any work done because you’re spending all your time hanging on but you get bragging rights.] The SAIA Code of Safe Practices for Suspended Scaffolds recommends 20 mph for single point and 25 mph for two point suspended scaffolds.

Q: Is a “Self-Propelled Elevating Work Platform (aka scissors lift) an aerial lift or a Mobile Scaffold?

A: According to an OSHA Letter of Interpretation (LOI), OSHA thinks it’s a supported scaffold, similar to a frame scaffold. The industry knows it is an aerial platform because the consensus standards for it are in the ANSI A92 family of standards, not in the ANSI A10.8 standard which addresses the typical frame, systems, tube & coupler, and other like scaffolds.

Q: Are the OSHA scaffold standards instructions on how to use scaffolds?

A: Heck no; they are minimum requirements for safety, minimum expectations. In fact, you have to be trained in scaffolding before you can understand the regulations. Reading the standards does not a Competent/Qualified Person make!

Q: Why do I have to have a guardrail on a suspended scaffold if I am wearing personal fall arrest equipment?

A: We don’t want you to fall off the platform since catching you isn’t fun.

Q: Does that mean that when I am on a single or two point suspended scaffold I have to not only utilize a personal fall protection system but I have to be behind the guardrail system on the platform.

A: Duh—yeah.

Q: What about a multi-point suspended scaffold?

A: It depends on the scaffold. If the deck has many suspension points and the deck is very rigid, personal fall protection may not be necessary. On the other hand, if the deck is flexible, failure of one line can dump you off the platform. Ask the qualified designer what is required for fall protection. If nobody knows, use both a guardrail and personal fall protection. I would also recommend looking for a new job if nobody knows what the fall protection requirements are!

Q: If I stand on a plastic five gallon bucket, is it a scaffold?

A: You bet it is. A scaffold is any temporary elevated platform and its supporting structure used to support workers or materials or both. Assuming you turned the bucket over before you stood on it, the bottom of the bucket is your platform and the sides of the bucket are the supporting structure. I cannot tell you what the handle is.

Q: Does that mean that if I stand on a table I have to comply with the OSHA scaffold standards?

A: Why not? You’re using the table as a scaffold.

Q: Do I have to comply with the OSHA standards or do they only apply to my employer?

A: Nice try. The OSH Act of 1970 explicitly states that both the employer and the employee have to comply with the standards. [This is known as the “General Duty Clause” of the act.]

Q: What else does the General Duty Clause say?

A: It requires that the employer “shall furnish to each of his/her employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his/her employees.” This is also known as “Section 5(a)(1).”

Q: Do the OSHA standards cover all workplaces?

A: No. The federal OSHA standards do not cover state and local government employees; they apply only to the private sector.

Q: Do all 50 of the United States enforce the federal OSHA standards?

A: No. 21 states and 1 US territory have state plans that cover both private and state and local government workplaces. 5 states and 1 US territory cover state and local government workers only. Most states use the federal standards. Certain states have added to or revised the federal standards for use in their states. California’s OSHA scaffold standards are completely different from the federal standards.

Q: Why do states change the federal standards?

A: I have no idea—a broken arm in the Virgin Islands is the same as a broken arm in Alaska.

Q: I am on a project where the Army Corps of Engineers had authority. Do they use the federal standards?

A: Yes and no. They have to comply with federal OSHA but they also have standards that are referred to as EM-385 that are part of the contract. And yes, the EM 385 scaffold standards are much more stringent and more confusing.

Q: I was told that 19” is the maximum first step for accessing a scaffold. Is that correct?

A: Nope. It is 24 inches. 19 inches is the maximum first step for everything except scaffolds.

Q: Where do you find all this information?

A: I make it up, just like a lot of people on the jobsite. JUST KIDDING! The OSHA standards can be found at www.oshsa.gov; the Codes of Safe Practices can be found at www.saiaonline.org and www.ssfi.org. DH Glabe & Associate also keeps a wide variety of info on its’ resources page www.dhglabe.com/free-resources. The ANSI A92 standards can be purchased from the SAIA. Other standards can be purchased from ANSI or the American Society of Safety Engineers. Training on how to use scaffolds can be obtained from the SAIA and other sources. Be sure to investigate the quality of the training before purchasing—there are a lot of supposed experts who do not have the credentials.

Common or Unique?

By | Aerial Lifts, Scaffolding | No Comments

You think that a boom lift has little in common with a frame scaffold and you wonder why the US federal Occupational Safety & Health Administration, OSHA, combined the aerial lift standards with the scaffold standards in the same subpart.

You think it should be obvious that a stationary scaffold surrounding a building is nothing like a scissors lift or a mast climber. If that’s what you think, then you might be interested to know that they have a lot more in common than you think. Supported scaffolds, suspended scaffolds and aerial lifts are of the same cloth; there are strength issues, fall hazards, falling object hazards, stability concerns and access matters. It’s true—a boom lift has fall protection hazards just like a suspended scaffold does. Let’s face it, a fall is a fall. Who cares from what platform you fall. There is no doubt that there are unique circumstances for one piece of equipment that would not occur with another. For example, a boom lift can provide the operator with a catapult toss that one would not experience on a supported scaffold. Consequently, a boom lift operator needs fall restraint in addition to a guardrail system. Interestingly, besides the logical solutions to fall hazards, temporary elevated platforms have taken on a new dimension, mainly due to a misunderstanding of the hazards. Scissors lifts now have fall protection anchors, similar to boom lifts so that occupants can utilize fall arrest equipment in addition to a guardrail system that keeps them from walking off the platform. It appears to be an unnecessary inconvenience but some say that both suspenders and a belt are better. Simply stated, fall protection for temporary elevated platforms is determined by the type of equipment and the potential hazard: common hazard, unique solution.

It is unquestioned that all scaffolds must support the intended load. The common question asks how strong is strong enough. For supported and suspended scaffolds, each scaffold must be able to support four times the load applied while the suspension ropes for suspended scaffolds must be six times stronger than the intended load. That’s right, six times! Mast climbers have an interesting characteristic not often seen with other types of scaffolds. Unbalanced loads will tip the whole platform over, definitely not a good situation. Therefore it’s really important to follow the manufacturer’s recommendations regarding the placement of loads. This holds true for construction hoists where some people think that if the cage isn’t full, more load can be added. This is not a good idea.

Supported scaffolds can support thousands of pounds while boom lifts may be limited to a couple of workers. Suspended scaffolds can be designed for only a couple of workers and they can be designed for multiple personnel. The common thread is that all scaffolds, aerial lifts and construction hoists are designed to support loads; each exhibits a unique characteristic for doing so.

A proper foundation is required for any structure including construction hoists, aerial lifts and other scaffolds. Here a foundation is not the basement of the building but rather the support for the equipment. This foundation can be the ground, a floor, a roof, a beam, even water. That’s right; I saw a scaffold in a swimming pool supported by pontoons. Don’t ask!

A boom lift or scissors lift will apply its load through four wheels. As the machine drives around on the building floor it will exert loads in a way that may not have been anticipated by the design engineer. This may result in a damaged floor or worse. On the other hand, a mast climber typically applies its load to a very small base. Does the foundation have the capacity to support this type of concentrated load or does the load need to be spread out over a larger area? If the machine is setting on a floor, can the floor handle that type of load or will reshoring be required to transfer the load to a stronger foundation for the machine?

The common thread is that all scaffolds, aerial lifts and construction hoists require an adequate foundation. The unique attribute is how the load is applied to that foundation.

Access is necessary for any floor or platform, including temporary elevated platforms. However, what may work for a stationary scaffold won’t necessarily work for an aerial lift. Ladders are commonly used to access frame scaffolds although I cannot imagine using a portable ladder to access a boom lift. But I can imagine using a boom lift to access a frame scaffold. Its normally not a good idea to use a portable ladder to access a mast climber since the mast climber can exceed the height of the ladder, rendering it useless of worse; same thing with a suspended scaffold and an adjustable scaffold. Ramps work well with construction hoists and may also work well with a supported scaffold. Access is a common requirement, the solution is unique.

So, it does make sense to include supported scaffolds, those scaffolds whose platforms are supported by rigid means, suspended scaffolds, those scaffolds whose platforms are supported by non-rigid means, and aerial lifts in one set of standards. The hazards are common but the solutions are unique. Make sure you know both.

Suspended Scaffold Q & A

By | Resources, Scaffolding | No Comments

A suspended scaffold is a marvelous tool for workers to utilize to gain access to work locations that would be difficult if not impossible to otherwise reach. Unfortunately, the general perception is that suspended scaffolds, particularly two point suspended scaffolds such as window washers two point suspended scaffolds, are inherently dangerous and those individuals who use them are similarly inherently dangerous. This is due in no small part to the media exposure that suspended scaffold failures receive. The reality indicates otherwise. Perhaps these questions and answers will help mitigate the fear of suspended scaffolds.

What is a suspended scaffold? A suspended scaffold is a temporary platform that is supported by non-rigid means such as cables, chains or ropes. It is not to be confused with supported scaffolds which are temporary platforms that are supported by rigid means such as legs, posts or frames.

Is a suspended scaffold the same as a hanging scaffold? No. A hanging scaffold is a “temporary work platform without support from below, secured to an overhead structure using fixed length rigid suspension members” while a suspended scaffold utilizes non-rigid suspension members.

In addition to a guardrail system, are users of all suspended scaffolds required to wear personal fall protection equipment? No. A user of a single point or two point suspended scaffold, that is a platform suspended from either one rope or two ropes, must wear personal fall protection equipment properly connected to a lifeline. The reason for this requirement when using a single point suspended scaffold is obvious: if the rope breaks, you are in big trouble if you aren’t wearing a harness connected to a lifeline and anchor. On a two point suspended scaffold, typically only one line breaks, leaving the platform hanging vertically (and making really cool photos for the media) with one worker dangling from his lifeline while the other worker is desperately clinging to the other suspension rope.

Are you telling me that workers utilizing a temporary platform that is supported by four suspension wire ropes don’t have to wear harnesses secured to an adequate anchor?According to most regulations, yes.

That doesn’t sound right—are you messing with me? Nope.

Why doesn’t a multi-point suspended scaffold user have to wear a harness attached to an adequate anchoring system? It is assumed that the platform is sufficiently rigid so that if one suspension rope fails, the platform will remain more or less level and the workers will not slide/fall off the platform. Of course, if your platform lacks the necessary rigidity, you should be utilizing personal fall protection. For example, if you are suspended by three ropes, you probably need to utilize personal fall protection for the unlikely event that you will lose one of your suspenders. On the other hand, if you are on a rigid platform suspended by many suspension lines, such as a suspended platform under a bridge, personal fall protection is probably not warranted. Of course, you must always comply with the qualified scaffold designer’s instructions.

Why do single and two point suspension scaffolds seem to frequently fail? They don’t. If you look at how many suspended scaffolds are used daily in North America, you will find that the failures are insignificant. It’s just that the media likes to report them, You Tube likes to show them and people like to talk about them! (Of course, if you are the worker who experiences a failure, it probably won’t seem insignificant to you.)

Does a cantilever beam used to support the rope that supports an elevated suspended temporary platform have to be designed by a Professional Engineer? Maybe and maybe not.

When is a Professional Engineer required? First of all, the Professional Engineer has to be qualified. That qualified Professional Engineer is required for all multi-point masons suspended scaffolds where the cantilever beams used to support the ropes are secured to the floor. Usually a qualified Professional Engineer is required to design the cantilever beam and rigging, particularly if it is purpose designed for a specific situation. Also keep in mind that many agencies, such as Departments of Transportation, require a qualified Professional Engineer be involved.

Are suspended scaffold erectors required to utilize (wear) personal fall protection equipment? Erectors are expected to utilize personal fall protection equipment when they are exposed to a fall hazard, such as when they are installing rigging on a roof or open sided floor.

Do suspended scaffold users have to have a license/permit to operate a suspended scaffold? Perhaps; it depends on the jurisdiction. Large cities, some counties and state governments require licensing and/or permitting. Before starting any scaffold project, it would be wise to determine the necessary regulatory requirements.

Is a temporary suspended scaffold the same as a permanent suspended scaffold? No. Temporary suspended scaffolds must comply with a different set of regulations and standards than a permanent installation, known as a “PI.” As the names suggest, a temporary suspended scaffold is commonly used in the construction of new structures and intermittent maintenance while a PI is specifically designed for a building, installed permanently on that building, and is intended to be used for providing routine maintenance and renovation.

What appears to be the most common cause of suspended scaffold failures and why? The most apparent cause is lack of training. There are so many safety devices incorporated into temporary suspended scaffold equipment, such as overspeed brakes and extremely high safety factors that it requires ignorance and possibly purposeful stupidity to make them fail.

What is the most important aspect of suspended scaffold utilization?  Training.

Where can I get that training? One good source is the Scaffold & Access Industry Association.

Scaffolding Scores High – Unfortunately!

By | OSHA Standards & Regulations, Resources, Scaffolding | No Comments

Once again, scaffolding has shown its ability to frequently receive OSHA citations!  In fact, it shows up in the number three spot on the famous “OSHA’s 2014 TOP TEN Most Frequently Cited Violations” list.  (See Figure 1) According to OSHA, there were 4,543 scaffold violations: that’s about 17 every workday.  Unfortunately, it is unclear as to the breakdown of the citations; which hazard does each citation specifically address.  (Note that Fall Protection still holds the number one position with 7,170 citations, about 27 per workday.  Again, it is unclear what type of fall hazard existed that warranted a citation.)

How about having some fun with statistics?  While 17 scaffold violations per day is significant, it is worth comparing the 17 violations per day to the number of workplaces and workers in the construction industry.  According to OSHA, there were 89,664 inspections in 2013, about 345 each work day across the United States and its territories.  That works out to approximately six per state/territory each day.  Depending on the population of the state where you do business, this may or may not have you concerned.  Since there are 8 million worksites containing 130 million workers, the odds of having an inspection at least once in a year is one percent.  Does that mean that for every scaffold the same odds exist?  Yes and no.

Not every worksite has a scaffold so those sites should be excluded from the count.  And since the 8 million worksites include construction, manufacturing, retail and a zillion other worksites, an adjustment needs to be made if only the construction sector is to be considered.  So, as an example, let’s assume (guess might be a better word) that twenty percent of the work sites are construction related and that seventy five per cent of those construction sites have scaffolding.  That means that there are 1.6 million construction projects and that 1.2 million have scaffolds.  Obviously the scaffolds will vary in size based on the scope of each project.  While on one site only a small rolling tower may exist, on another site a scaffold 150 feet tall may have been constructed.  For argument’s sake, let’s argue that on average each site has a supported scaffold that is 7 tiers high and 100 feet long.  (Of course any of these projects could have aerial work platforms and/or suspended scaffolds but these scaffolds will not be considered for this example.)  Depending on the equipment being used, the scaffold could have more than 1,000 components.  This would then mean that there could be 1,000 problems which in turn have the potential of creating 1,000 citations.  Since we assumed that there are 1.2 million jobs with scaffolds, and each job has 1,000 scaffold components and potentially 1,000 violations, there are then 1,200,000,000 (that’s 1 billion, 200 million) possible violations looking for citations.  This number suggests that since there were only 4,543 citations, either the compliance officers aren’t doing a very good job or only 0.0004 % (that’s four-ten thousandths) of scaffolds had problems.  Since OSHA compliance officers do a good job, it can only be concluded the industry is doing a superb job of constructing and using scaffolding since 99.99962% are flawless!

Although one could reasonably assume that there may be a flaw or two in this analysis example, the fact still remains that the overwhelming majority of scaffolds are constructed properly.  Therefore it is time to step back and consider whether the present method of measuring safety is accurate since it is well known that accurate measurement is critical if the root cause of scaffold accidents is to be determined.  Furthermore, how can full safety be achieved if the problem isn’t understood?

Historically, scaffolds have been considered to be dangerous and downright life threatening.  This perception assuredly contradicts the evidence:  How can scaffolds be dangerous if 99.999% of scaffolds are constructed without flaws?  Furthermore, how can scaffolds be dangerous if each scaffold is designed and constructed properly?  A properly designed and constructed scaffold has no hazards.  And please, don’t tell me that you can still fall off a properly constructed scaffold.  A properly constructed scaffold won’t let you fall off—you’ll have to jump.

On the surface, the “OSHA Top Ten” continually paints a bleak picture for scaffold safety.  But this analysis shows that it is just not true.  Unfortunately the statistics are taken at face value without considering the bigger picture.  While any violation is undesirable, it doesn’t necessarily indicate a serious flaw in the scaffold industry.  And finally, the Top Ten list only indicates the number of citations written, not an accurate count of the citations that ultimately remained and accepted by the employer.  Nor does the list indicate the severity of the violations.  Frankly the only conclusion that can be made is this:  Scaffolding shows up on the OSHA Top Ten list—so what.  The list is meaningless in that it fails to truly indicate the safety or menace of scaffolding.  On the contrary it misleads and thus wastes the efforts of those who are assigned the task of evaluating jobsite safety.  It would be better to not have the list.  Think about it.

OSHA TOP 10 MOST SERIOUS VIOLATIONS

1.     Fall protection  (c)
2.     Hazard communication
3.     Scaffolding  (c)
4.     Respiratory protection
5.     Ladders  (c)
6.     Powered industrial trucks
7.     Lockout/tagout
8.     Wiring methods
9.     Machine guarding
10.  Electrical: systems design

C = Construction standard
Figure 1

Source:  www.osha.gov

Unknown Knowns

By | OSHA Standards & Regulations, Resources, Safety Hazards, Scaffolding | No Comments

It seems that speculation runs rampant at the beginning of every year as forecasters speculate about the economy, markets, jobs, stability and politics. Along those lines, it is time to speculate about the future safety of the scaffold and access industry. More specifically, will scaffolding still rank up there in the OSHA top 10 list of citations at the end of 2015 or will the industry somehow miraculously alter the trend? More importantly, is scaffold safety accurately measured by using the OSHA Top 10 as a reference?

It is generally accepted that OSHA regulations address hazards. Take, for example, the requirement that all extension ladders must extend at least 3 feet (0.9 m) above the upper landing surface. The hazard here is that the worker loses stability while exiting or accessing the ladder. Infractions of this regulation are often cited and consequently show up on the OSHA Top 10 list of citations, suggesting that employees are frequently injured and killed because the ladder doesn’t extend 3 feet above the landing. Since the hazard is a lack of a handhold as the ladder user exits or accesses the ladder, can it be reasonably assumed that the lack of the ladder extension always results in injury or death? Can the correlation be made that the number of citations equals the severity of the hazard? Or is there another explanation that has very little to do with the hazard?

Using the ladder regulation as the example, it is my opinion that the number of citations has more to do with the ease of identifying a violation of a given citation than it is has to do with the severity of the hazard. While it is true that losing your grip while exiting a ladder can result in an injury or even death, it is also true that it is very easy to identify whether a ladder is extending 3 feet above the landing surface or not. In fact you can probably spot this violation while driving down the street. It’s a no-brainer citation. On the other hand, how many citations have been written for a safety factor (29 CFR 1926.451(a)(1) violation where it takes some analysis and calculations to determine if a violation occurred?

The same “no-brainer citation” argument can be used for guardrail systems, particularly on scaffolds. A quick look at a scaffold will determine if the guardrail has been installed. Bingo – another easy citation! This is not to say that fall protection regulations should not be enforced, especially since falls in construction are a leading cause of injuries and death; rather guardrail violations are easy to identify and therefore it is not surprising that guardrail violations consistently show up on citation lists.

Donald Rumsfeld, former U.S. Secretary of Defense said it best: “There are known knowns. There are known unknowns. There are unknown unknowns. But there are also unknown knowns. That is to say, things that you think you know that it turns out you did not.” The secretary’s wise words of wisdom can be applied to the subject at hand. The known known is the number of citations. But wait; there is an unknown known. The number of citations does not necessarily indicate the severity of the hazard but rather the number of citations for a specific regulatory infraction. Frankly, I think it indicates the ease of citation. If a worker falls from a scaffold, it is typically concluded that the lack of fall protection is to blame. But is it? Was the investigation sufficient to warrant such a conclusion? Were the investigators qualified to make such a determination?

Because the OSHA “Top 10 most frequently cited OSHA standards violated” list is commonly used to evaluate the safety of a specific sector of the industry, and because scaffold citations always appear in the Top 10, scaffolding is frequently perceived as a dangerous product in a dangerous industry.   Perception leads to faulty conclusions which of course leads to more faulty conclusions. The Top 10 list can be dangerous if not used properly.

Consider this: Federal and state OSHA has approximately 2,200 inspectors who did 89,664 inspections in 2013. (41 inspections per inspector—not quite one per week on average.) Federal OSHA did 39,228 of those inspections utilizing a budget of $535,246,000.00 to do so, or $13,645.00 per inspection. Are we getting our money’s worth? It is very important that first, citations are accurate and secondly, they stick. That is, the employer agreed to the fine and/or the validity of the citation. Just because a citation was issued doesn’t mean it was a valid citation. Many citations are unwarranted and never result in a fine or agreement by the employer that a violation occurred. Unfortunately this may not show up in the Top 10 List, leading to faulty conclusions.

So, here are the known knowns: Worker deaths have decreased from 38 deaths a day in 1970 to 12 a day in 2012 – that’s good. The bad news is that in construction, 796 workers died in 2013; that means 3 workers in construction died per day! 294 of those deaths were from falls. Here are the unknown knowns: How many falls were from scaffolds? And then there are the unknown unknowns: What were the dead workers doing before they decided to fall to their deaths? Was it a faulty scaffold? Was it an untrained worker? Was it suicide or murder? Was it work related? Was it the employer’s fault? Was it the employee’s fault? Was it a design error (scaffold designer’s fault)? Was it a scaffold supplier error? Or was it an unknown unknown because “things that you think you know that it turns out you did not”? And to think that we know! By the end of 2015, we will know the number of citations (the known known) but will we know the unknown? If history is any indicator, probably not; don’t let statistics be the sole criteria; as the saying goes: “It’s what you don’t know that will kill you.” According to Secretary Rumsfeld, it appears that would be the unknown unknown.

Statistics in this article came from OSHA and can be found at www.osha.gov.

Shore Enough, It’s Scaffolding

By | Resources, Scaffolding, Shoring | No Comments

Regulatory Differences Between Shoring and Scaffolding

It is not all that uncommon for a scaffold equipment supplier to also be a shoring equipment supplier. After all, both are used on a temporary basis, have similar components and are designed to support loads. While shoring equipment normally supports heavier loads, scaffold frames can as easily be used as shoring as shoring can be used as scaffolding. (The shoring referred to here is the equipment that is used to either support fresh concrete while it is curing (getting hard) or to support existing structures. It is not the equipment used to restrain soil in excavations and trenches.)

Of particular interest are the applicable regulations for scaffolding and shoring. Is shoring the same as scaffolding? Do the regulations that apply to scaffold erectors also apply to shoring erectors? After all, frame scaffold is just like frame shoring—or is it? These are good questions that deserve accurate answers. The quick, or fundamental answer, is that scaffolding is not shoring and shoring is not scaffolding. Since the work activity, and not the equipment, describes the equipment’s function, it just doesn’t matter if scaffold frames are used to shore up concrete any more than if shoring frames are used to support a work platform.

Applying Federal OSHA standards

Here is how the federal OSHA standards get applied. It is necessary to determine what the elevated platform/deck is being used for. Is this elevated platform used to support employees or materials or both so that the workers can reach the work area? For example, are the employees masons who are laying up brick and block? If so, then the elevated platform, and the supporting structure, is a scaffold. On the other hand, is the primary purpose of the elevated platform to support fresh concrete? If so, then the deck is a “horizontal walking/working surface.” The significance here is that the purpose of the deck must be known so that the correct standards are utilized. What happens when the work surface is used to support employees who are using it to reach a work area and the work surface is also being used to support concrete? What about the walkway around the perimeter of the deck that is used to support concrete? Well, here is how it works: Say that you have an electrician using the deck/platform to reach a location to install conduit and electrical boxes. Since the electrician is using the work surface as a scaffold platform, the platform must be able to support itself and four times the intended load. In addition, the guardrails must comply with the scaffold standards, there must be access in compliance with the applicable scaffold standards and any exposed employees must be protected from falling objects.

On the other hand, if the work surface is being used to support concrete, then it must comply with the applicable fall protection, access and formwork standards that address that work activity, including the concrete and formwork standards, 29 CFR 1926, Subpart Q, the fall protection standards at 29 CFR 1926, Subpart M, and the access requirements found at 29 CFR 1926, Subpart X. Typically, if these standards are met, then in the example where the electrician is using the platform to access her work, she will also be in compliance with the scaffold requirements due to the fact that the scaffold regulations are generally not as restrictive as the fall protection and access regulations for working surfaces.

Where are the Differences?

Where are the differences? For the guardrails, in scaffolding the guardrail height is 38 inches to 45 inches while for an open-sided work surface the range is 39 to 45 inches. Access in scaffold requires that the first step is not more than 24 inches while it is 19 inches for a floor or other work surface. Falling object protection standards are similar for both scaffold platforms and other work surfaces although the safety factor for a scaffold platform is 4 while the safety factor for a deck supporting concrete is whatever the employer feels is correct. (ANSI and the SSFI recommend a 2 to 3 safety factor.)

What should be done with erectors? While the temptation is to consider shoring equipment erectors to be the same as scaffold erectors, and therefore the scaffold standards should apply, the reality is that shoring erectors are not scaffold erectors. Consequently, the scaffold regulations do not apply. This presents a quandary when it comes to the application of the appropriate standards. Is climbing a shoring frame access or a working surface? When do shoring erectors use personal fall protection? Or do they?

Well, here is how federal OSHA views it. A shoring frame is a vertical walking/working surface. Consequently, personal fall protection is required when climbing a frame. Standing on a plank at the top of a shoring tower is considered to be an open-sided platform; fall protection is required. Walking/climbing between shoring towers is not normal access so therefore the access standards would not apply. But the fall protection standards would apply.

As for the walkway around a formwork deck supporting concrete, it is considered an open-sided horizontal work surface. Therefore a guardrail system is expected and it must comply with the regulations in Subpart M where the toprail must be at least 39 inches above the deck and no more than 45 inches.

Focus on Purpose and Safety

Confused? The bottom line is that you need to look at the purpose of the work surface. This will determine if it is a scaffold platform rather than a horizontal work surface. And as for the employees installing the rebar and inserts in preparation for placing the concrete, although they appear to be using that deck to access their work and consequently it appears it would then be a scaffold platform, these employees are doing work to the deck which then makes that deck an horizontal work surface and not a scaffold.

Still confused? Focus on safety—not the regulations.