Concerned by reports that the precast concrete products industry (SIC 3272) has an injury incidence rate which is consistently at least twice that of the national average, the National Institute for Occupational Safety and Health (NIOSH) began developing this document with the intent of providing recommendations aimed at reducing worker exposure to hazards.# PREFACE
The Occupational Safety and Health Act of 1970 (Public Law 91-596), states that the purpose of Congress expressed in the Act is "to assure so far as possible every working man and woman in the Nation safe and healthful working conditions and to preserve our human resources...by," among other things, "providing for research in the field of occupational safety and health...and by developing innovative methods, techniques, and approaches for dealing with occupational safety and health problems."
Later in the Act, the National Institute for Occupational Safety and Health (NIOSH) is charged with carrying out this policy.
One method by which NIOSH responds to this charge is to publish Technical Guidelines.
Technical Guidelines present the results of comprehensive systematic analyses of occupational hazards, and suggestions for preventing injury and disease among workers.
They are intended to supplement existing Federal safety and health standards and may provide background useful in formulating new standards for development.
In the interest of wide dissemination of this information, NIOSH distributes Technical Guidelines to other appropriate governmental agencies, organized labor, industry, and public interest groups. We welcome suggestions concerning the content, style, and distribution.
This document provides guidance for protecting workers in the precast concrete products industry. It was prepared by the staff of the Division of Safety Research in conjunction with the Division of Standards Development and Technology Transfer, NIOSH.
I am pleased to acknowledge the many contributions made by reviewers selected by the Prestressed Concrete Institute (PCI), the American Concrete Pipe Association (ACPA), and the National Precast Concrete Association (NPCA); other reviewers and consultants; representatives of other Federal agencies; and the staff of the Institute. However, responsibility for the conclusions and recommendations belongs solely to the Institute. All comments by reviewers, whether or not incorporated into the final version, are being sent with this document to the Occupational Safety and Health ^Administration (OSHA^ for consideration in standard setting.
The document characterizes the industry and describes the operations, tasks and processes required to manufacture precast concrete products.
The magnitude of the occupational safety problem in the precast concrete products industry is defined through presentation of injury and illness incidence rates.
In support of the document's systematic approach to the identification of industry hazards, a detailed analysis of 1,319 accident case histories was performed.
This analysis identifies the tasks, tools, and equipment that are the most hazardous to the worker.
For example, materials handling tasks, both manual and mechanical, accounted for 28.0% of the total injuries studied.
Tasks associated with welding, burning and cutting accounted for 4.6% of the total injuries. Some of the specific tools found to be particularly hazardous to precast concrete workers include: hoists and cranes, which accounted for 4.4% of the total injuries and 40% of the fatalities; unpowered handtools, which accounted for 5.7% of the total injuries; and powered handtools, which accounted for 5.8% of total injuries. The determination of how workers are injured during precasting operations led to the formulation of comprehensive safety recommendations.
The recom mended engineering controls and/or operational safe work practices offered are applicable to product manufacture and delivery to a construction site only, and do not address erection or installation procedures.
To further enhance the document's usability for small to middle-sized pre casting plants, a chapter addressing safety management principles is presented. The Romans used the product in ashlar work (stone and brick) and as concrete in building harbors, piers, canals, and water supply and sewerage systems.
The remains of ancient structures reveal that building materials progressed from relatively simple applications of natural materials to cast concrete, one of the earliest substitutes for natural stone. Despite the ravages of time, weather, and warfare, many ancient concrete structures remain to give testimony to their durability.
Following the Roman period, the use of cement and concrete had a long period of dormancy until the emergence of studies by the early British civil engineers in the late 18th century.
During the 19th century, after the successful development of the Erie Canal under Governor DeWitt Clinton of New York, engineering projects increased the need for cement and concrete. New sources and techniques were developed, transportation improved, industrial growth expanded, and concern for public health emerged. Transportation requirements created a demand for railways, highways, storm drainage, and bridges; buildings required structural and architectural elements; and improvements in public health called for sewerage, water storage, and water distribution systems.
Technological advances, beginning with reinforced concrete and culminating in contemporary prestressing methods, have made longer, stronger concrete members possible.
Thus, concrete has grown out of a mere supplemental relationship with steel into direct competition with it in construction of varying projects.
The widespread use of standardized precast/prestressed concrete products, such as architectural panels, pipe, etc., has brought about the prevalence of fixed, permanent plants for manufacturing concrete products.
The improvement of transportational methods and systems has contributed to the evolution of the precast concrete plant, in that it has become cost efficient to mass produce concrete products and transport them to the various construction sites rather than cast members on-site.
Such plants capably produce job-specific, one-of-a-kind product as well, offering an alternative to poured-in-place operations, or casting operations adjacent to actual construction sites.

# B . Scope
This document concerns occupational exposure in the manufacturing of precast concrete products (SIC 3272). Examples of products manufactured within SIC 3272 are contained in Appendix A.
Contractors engaged in concrete construction work including on-site precasting of concrete products are classified in the construction industries and are not considered in this document. Other industries concerned with manufacture of concrete products which are excluded from the scope of this document are:

# CHAPTER II DESCRIPTION OF THE PRECAST CONCRETE PRODUCTS INDUSTRY
In this chapter the precast concrete products industry is described, its structure is examined, the number of plants and the size of the work force are defined, and the labor and trade organizations associated with the industry are identified. An operations approach that follows the production flow is used to give a description of specific manufacturing techniques or processes, the tasks performed by workers within each operation, and the tools and equipment associated with such operations.
Concrete is a building material made by thoroughly mixing cement; sand; aggregate, such as gravel or crushed stone; and water in desired proportions.
The cementitious material usually is a hydraulic cement that sets and hardens in water.
Initially, the concrete mix is a plastic material that assumes the shape of the mold into which it is cast.
The mixture is poured into a cavity, an excavation in the ground, or a form designed for a specific purpose.
After hardening, concrete has the appearance and structure of stone.
In fact, it may be thought of as "moldable stone." When the mixture is deposited in its final position, it is known as cast-in-place concrete.
When a concrete product or element is cast elsewhere (whether in a plant or on a field site) and then brought to its final position, it is termed precast concrete.
Precasting is a manufacturing procedure, whereas casting-in-place is a construction procedure.
Being a manufacturing operation, precasting can have certain advantages: o Work can be performed at a fixed site with accelerated curing facilities. o A single location for batching and mixing concrete can be provided, o A convenient source of water and other raw materials can be used, o A location convenient to transportation facilities can be selected, o Mass production techniques can be employed. o Opportunities for storing product and working under shelter reduce the impacts of cyclical demand and weather conditions.

# A. Plant Census and Worker Population
The precast concrete products industry is entrepreneurial, highly diversi fied, and geographically dispersed, with nearly 4,000 disparate plants manu facturing more than 600 different products.
The NIOSH Industrial Profile data for 1980 (Table II-1) show that 3,930 precast concrete manufacturing plants employ about 82,049 workers .
These figures compare well with information derived from the 1979 Pennsylvania Industrial Directory .   , 1979 Pennsylvania Industrial Directory , and 1977 Census of Manufacturers , Information supplied by trade associations also verifies the plant census figures in the NIOSH profile. The American Concrete Pipe Association (ACPA) , the Prestressed Concrete Institute (PCI)  and the National Precast Concrete Association (NPCA)  estimations of worker population corroborate the NIOSH profile figures. Further, the trade associations estimate that the precast concrete industry is comprised of approximately 62,500 production workers. This equates well with the aforementioned NIOSH profile total population of 82,049 workers, and the Department of Commerce Census estimation that approximately 77% (or 63,178) of the total worker population in the industry are production workers.
Table II-3 presents these trade association estimates.
For the purposes of this study, the NIOSH Industrial Profile data was used since it was the latest compilation of data on the industry. *From Duffy J. J. American Concrete Pipe Association . From Freedman S. Prestressed Concrete Institute . *From Tilford J. E. National Precast Concrete Asso ciation  .

# B. Process and Task Descriptions
This section describes the operations, tasks, and equipment required to manufacture precast concrete products. These descriptions are presented in organizational groupings that follow the primary production steps necessary in the precasting process. In many instances, the operations, tasks, and equipment described under a particular process heading are not unique only to that specific process; however, it is convenient to present the task descriptions in the sequence of the production flow. An additional section on materials handling is presented following the production task descriptions.

# Forming
Forms or molds used for the casting of precast concrete products us ually are made of steel or wood.
However, they may be constructed of any material that remains stable during casting and is able to withstand the abuse of preparation, installation of steel reinforcement, oiling, curing, stripping, and reuse. Wood is commonly used for the construction of forms expected to have a limited use; that is, forms built for the casting of fairly unique concrete products. Concrete is sometimes used as a form because it can be cast into intricate shapes. With a dense, smooth surface finish and the application of form release agents, concrete is an excellent form material for products requiring smooth or curvilinear surfaces. Styrofoam, fiber glass, rubber matting, and various paperboards are also occasionally used to make forms or form liners for special surface effects.
Because many of the products manufactured in the industry are produced repetitively, steel forms are common.
Such forms are usually made to design specification by other departments or are purchased as standard equipment from other form manufacturers.
Occasionally, it is necessary to modify or customize steel forms; that is, holes, notches, and sections may be burned out or fillets, boxouts, and seats may be welded in place as needed.
Large forms may be equipped with access ladders, stairways, work platforms, conveyor connections for receiving concrete, and external vibrators for consolidation.
Steel forms are hammered, vibrated, modified, and moved, creating dents, holes, and misalignments that require periodic repair and mainten ance.
In addition to welding shops, many plants have portable welding equipment for repair and modification of forms too large and unwieldy to move. Welds and patches are occasionally required to fill in depressed spots; chipping and grinding operations are used to smooth rough areas.
The form surface against which the concrete will be cast must be clean and smooth (unless specifically designed otherwise).
Forms are cleaned for reuse by chipping, wire brushing, scraping, scrubbing with water, sanding, and/or air blowing.
Form assembly follows repair and cleaning. Large forms are moved to the casting station by overhead hoists or cranes, or by lift truck.
Many products have interior and exterior forms.
Often, the interior form is placed and fixed to a cleaned steel plate, or pallet ring that forms the bottom of the product.
Exterior forms are then locked into place with various fittings (makeup bolts, tack welding) that both fix its position and maintain the required dimension between the interior and exterior form.
Forms for long or flat products require minimum assembly, except to position the edges, bulkheads, and boxouts at the desired locations. Edges and bulkheads usually require appropriate spacers, spreaders, braces, and stiffeners.
These pieces are usually cut from wood to the proper length, hammered into place, and held by nails. Hammers are used for driving nails and tacking chamfer strips in wood forms. Sledge hammers, crowbars, and prybars are used in the alignment of forms as well as during the placement and removal of bulkheads.
The tasks and equipment used during the construction of the forms are typical to wood, Styrofoam, or fiber glass assembly/manufacturing pro cesses.
Most companies have carpenters' shops or areas equipped with hand and power tools for form construction.
Larger companies usually have full-time personnel to use this equipment while smaller companies usually assign workers the task of making the form as part of their other routine responsibilities (casting, oiling, mixing, etc.).

# Oiling
The form surface is coated with a release agent to keep the fresh concrete from bonding to the form. Form release agents usually have a kerosene or paraffin base and are applied to the form by swabbing or spraying before the reinforcing steel is placed.
Swabbing is the hand application and spreading of the agent on the interior surface of the form with the use of brooms, mops, rags, or brushes. Swabbing operations require a worker to fill a container (buc ket) with form oil from a drum, transfer it t:o the form, and physically apply it to the form walls. Usually the worker will swab while standing and walking in the form. Some forms (vertical walls) may require the worker to stand on the form structure and mop the walls.
Most spray application of form oil is by hand-pumped, hand-carried sprayers similar to garden insecticide sprayers.
The pump is filled from a central drum and carried by the worker to the form.
Typically, the worker will walk along the edge of the form and spray the required surfaces.
Some precast plants use a central pressurized air venturi system instead of hand pumps to spread the form oil.

# Reinforcing
The reinforcing operation includes the fabrication and placement of steel reinforcement into the product forms. The tasks associated with this operation are cutting, bending, tying and welding of rebar, wire and wire mesh; and stringing and stressing of steel strand. The reinforcement, once sized and shaped, may be assembled in the form or fabricated outside of the form in a separate area or shop. The movement or placement of the steel may be done mechanically or by manual means.

# a. Plant Fabricated Steel
Manual fabrication of reinforcing assemblies is common. Some times reinforcing bars or welded wire fabric are placed and tied in the form. For more complex assemblies, a jig is built to position bars. Transverse and shear steel is manually tied to the longitud inal steel with wire and pliers or with looped-end wire ties and a special "pigtail" tool that twists the two ends of the wire tie together when pulled. To produce reinforcing bars with the bends, loops, angles, and hooks specified by the design, a rebar bender is used. A cage or mat can be made to any desired size or shape. The completed plant fabricated reinforcing steel assembly is then lifted and placed in the form by manual or mechanical means. With prestressed concrete products, individual stirrups or welded wire fabric used for shear reinforcement are hand placed and may be tied to the prestressing steel.
Circular or elliptical reinforcing cages for concrete pipe are usually made of welded wire fabric (2-to 4-inch mesh made from 1/8-to 3/o-inch wire) or cold-drawn steel wire.
A wire roller forms rolls or flat mats of welded wire fabric into the desired circular shape, which is then cut and spot welded to make the cage.
Both cage machines or mandrels can be used to form steel wire into cages.
In a cage machine, the operation is continuous and the endless cage produced is cut to the required length; in a mandrel operation, each cage is made individually to the desired diameter and length. Both techniques require that the wire mesh be shaped into a cylinder (by rolling or bending), the ends joined (by welding or using tie wires), and the finished reinforcing cage placed into the annular space of the pipe form.

# b. Prefabricated Steel
Many small precast concrete products are reinforced by prefab ricated steel manufactured to specification by others. This prefabricated steel is placed, tied, or secured into the form or pressed into the freshly cast concrete at the desired locations.

# c. Steel Plates and Rolled Sections
For connecting some structural and architectural precast concrete products, small, rolled, sectioned steel plates with reinforcing bars or studs welded to them are tied to the cages inserted in the freshly placed concrete.
Wire loops of prestressing strand or reinforcing bars are tied in place or inserted manually for lifting and handling the finished product.
Connection and handling steel is called "hardware," and should be designed by the plant engineering staff or the project engineer.
The tasks necessary when using steel plates are similar to those described in the preceding sections.

# d. Prestressing Steel Strand
Prestressing steel is usually seven-wire strand that is manually or mechanically strung in the form before concrete is cast.
Manual strand stringing is performed by a worker physically pulling the length of strand down the bed from a reel stationed at one end of the bed.
The strand is then cut by torch or strand saw, and the process is repeated. Mechanical stringers pull multiple lengths of strand from separate reels at the same time.
Single or multiple strands may be threaded through cages of reinforcing steel and through bulkheads used to separate adjacent members.
The steel wire strands are laid in the stressing bed (a long form up to several hundred feet in length with the cross section of the desired shape) and fixed at the ends (abutments).
The stressing bed is the mold for several precast units along its length.
For example, if 50-foot-long "double tees" are desired and a 610-foot-long stressing bed is used, 12 such units can be produced in one bed, each separated by a bulkhead. Some beds are designed as selfstressing forms, eliminating the need for end abutments.
Once the strands are in place they are then stressed. This operation is the tensioning (stretching) of wire strands previously positioned in the form.
Stressing includes strand vise placement, jacking, tensioning, harping, and detensioning.
The stressing operation can be done by single strand jacking or multiple strand jacking where all the strands are tensioned at the same time.
The strands to be stressed (usually 1/2-inch, seven-wire strand , tensioned to approximately 200,000 pounds per square inch (psi) or a 30,000 pound load) are anchored at one end of the bed with a strand vise.
The strand vise barrel has a truncated conical hole along its longitudinal axis that holds the three jaws of a chuck.
The chuck is serrated on the inside surface and conical in shape outside. The jaws permit free movement of the strand in one direction.
In the other direction, they grip the strand and wedge themselves into the conical hole in the barrel of the strand vise.
A strand vise is placed over each length of strand at the anchor end abutment, which fixes it in place. At the jacking abutment, two strand vises are placed on the strand in opposing directions.
One is seated against the end abutment and allows the strand to be pulled through as the jack tensions the strand.
This strand vise also holds and anchors the tensioned steel to the abutment. The other strand vise provides a grip for the jack.
Figure II-l shows a rectangular prestressed beam form with strands stressed and reinforcement in place.
The steel strand may run straight through the bed and may be stressed in this position.
Alternatively, the strands may be depressed within the form for each member along the bed to create an upward force that improves structural efficiency . This technique is called draping or harping.
The term "draping" describes the profile of the steel strand, which is "draped" from its high point near the ends of each precast member to the low point at the midspan of each member.
Strands can either be depressed or pulled up.
Tine strands are passed through and over pin and roller fixtures that minimize friction at the points of change in the steel strand profile.
Figure II-2 shows the strands depressed at the midpoint of a member, thus creating the appearance of strings on a harp. Some designs may require other holddown locations for each member.
After the concrete is cast and has gained the specified strength (us ually 3,500 psi or more ), the strand tension is released, or detensioned.
In some cases, strands are individually cut by torch; however, with hydraulic jacks, the tension is gradually released from the header.

# FIGURE II-2. A "SINGLE TEE" SLAB WITH THE STRANDS HELD DOWN AT THE MIDPOINT
TO "HARP" THE PRETENSIONED STEEL Adapted from Bennett W. B. Jr. .
Detensioning transfers the stress from the steel to the concrete to which it has bonded, precompressing the concrete.

# Concrete Mixing
Concrete may be batched and mixed at the products plant or purchased from a ready-mix concrete producer. The correctly weighed proportions of cement, aggregates, and water are charged into a drum mixer, pan mixer, or a transit mix truck.
Small mixers that are used in many miscellaneous products plants are gas, diesel, or electrically powered.
Cement may be delivered to the plant in bulk cement trucks or railroad cars and unloaded by a totally enclosed, screw auger pneumatic system that carries the cement to an elevated hopper or silo.
Aggregates for larger plants are unloaded in much the same way as cement, except that open conveyors may be used.
The material stored at a higher elevation is weighed and chuted by gravity (charged) into the mixer.
The proper weight of water is added, and the mixer blends the components into a homogeneous mixture by rotating paddles inside an enclosed vessel at speeds of 2-15 revolutions per minute (rprn), or approximately 2 linear feet per second.
The two most common types of mixers used in the industry are drum mixers and pan mixers.
A drum mixer is a rotating cylinder in which sta tionary paddles, mounted along the cylinder, mix the concrete (truck mixers are of the drum type, inclined from the horizontal).
The pan mixer consists of a shorter cylinder than the drum mixer and is vertically oriented; paddles are mounted vertically and rotate to mix the concrete in the stationary cylinder.
The mixer is usually positioned 10-15 feet above the adjacent working surface to allow gravity discharge of the mixed concrete into buckets, trucks, or other means of conveyance to the casting area.
Access for cleaning, maintenance, or concrete quality control is provided by ladder or steps to a working platform that will partially or totally encircle the mixer.
Figure II-3 depicts a concrete batching, mixing, discharge, and transport system.
At the end of each shift or after mixing is completed for the day, the mixers are cleaned.
In addition to daily cleaning and flushing of concrete mixers, it may be necessary to hammer or chip away built-up en crustations of concrete on a periodic basis.
Mixers also require maintenance, paddle replacement, and repair.
All of these tasks may require workers to enter the mixers.

# Concrete Delivery and Casting
Casting of small products can be a manual operation; a quantity of mix is made available to the operator, who trowels or shovels it into a prepared mold around the reinforcement. The material may be hand tamped or vibrated to consolidate the mix.
Many small products are made with high production, automated equipment.
For casting larger pieces, the concrete is delivered from a truck, a concrete bucket, or a concrete buggy moved to the location where the concrete is to be used.
For very large pieces or for long-line prestressing beds, the concrete may be delivered by a monorail bucket system, overhead bridge crane, or other mechanical means and deposited directly in the form, where it is vibrated and consolidated by machinery or by manually inserted spud vibrators.
Usually two to five employees will be directly involved in these tasks.
In addition, concrete may be extruded through a die to form products such as hollow-core slabs.
Systems used to deliver the mixed concrete to the placement location vary from simple manual handling to totally automated, enclosed convey ances.
Concrete mixed in small power mixers is delivered by direct deposit (when the mixer or form is portable), by front-end loader (which carries concrete from mixer to form), or by wheelbarrow.
Ready-mix trucks frequently are used to deliver concrete because they can carry, and continuously mix, large volumes (up to 12 cubic yards) directly to or near the forms for placement. A chute, attached to a lip below the discharge opening of the truck's drum mixer, is directed by a worker to deposit the concrete.
The chute is moved around during the casting process to spread the concrete and reduce shoveling or raking.
As parts of the form are filled with concrete, the truck moves along the form, placing concrete to the desired level.
The process continues, FIGURE II-3. CONCRETE BATCHING, MIXING, DISCHARGE, AND TRANSPORT SYSTEM using additional ready-mix trucks with loads of concrete, to completely cast the products being made. During casting, workers will be engaged in a series of continuous tasks directed at filling the form with concrete.
When a ready-mix truck is used, workers will be working adjacent to and along with the movement of the delivery truck. Access (steps or ramps) to low forms (1-3 feet high) is usually limited or nonexistent. Employees will frequently be working and moving among multiple form tiedowns, spacers, and spreaders as well as walking on the reinforcing mats while filling and vibrating the forms. When it is not possible for a truck to deposit concrete directly into the form, wheelbarrows, hoisted concrete buckets, or concrete delivery vehicles are used.
Workers may push wheelbarrows along walkways, planks, or ramps to fill the form with concrete.
Another method of delivering concrete is by transporter, which takes mixed concrete from a central mixer and carries it directly to the forms.
Enclosed transporters have a smaller capacity (up to 6 cubic yards) and are usually lighter, smaller, and more maneuverable than ready-mix trucks. This method of depositing concrete is similar to that for ready-mix trucks except that the chute is tubular in shape, with an enclosed auger or conveyor belt, allowing concrete to be pushed to higher elevations instead of depending on gravity. Some transporters consist of wheeled or tracked carriers that take large buckets or hoppers of mixed concrete (up to 4 cubic yards) to placing or casting machines.
Transporters may travel on aisleways, rails, or roadways at speeds of up to 500 feet per minute.
Transfer, turnaround, or backing areas may be provided at the end of the travelway s for moving the transporters laterally relative to the casting areas or for access to the concrete mixers.
Visibility may be limited because of walls, corners, other equipment, storage, or layout. Once the concrete buckets have been delivered to the casting area, an overhead hoist, which may be an integral part of a casting machine, will be used to hoist and position the bucket over the form or casting hopper.
Conveyors are frequently used to deliver concrete to the point of placement, especially in the miscellaneous and pipe sectors of the industry.
The forms can be set up under the discharge end of the conveyor, or a portable conveyor can be set up with its discharge over the forms (depending on form mobility).
Concrete is deposited onto the conveyor and moved along the conveyor system (which can be arranged to move the concrete around corners, to different elevations, or to remote plant locations) to the point of discharge.
Access to elevated forms during casting is usually provided by plat forms, stairs, movable scaffolds, or ramps.
Large pipe forms and mis cellaneous products forms will sometimes have walkway platforms built around the forms or attached for the casting operations.
Ramps are a convenient means of access to forms at elevations different from the surrounding working surface; otherwise, stairs are used.
Access to lower beds up to 3 feet above the plant or yard surface usually is by stepping up and jumping down; it is uncommon for steps or ramps to be provided- In mechanized plants, placement of concrete into lorigbed forms is accomplished by placing or casting machines, similar to pavers or extru ders.
The concrete is spread, vibrated, compacted, screeded, and finished as the machine passes over the form, or is extruded as it moves along the bed. Drive controls are located in a cab on the machine or on a panel reached by workers from the side of the machine.
One method of casting utilized in the manufacture of pipe and many miscellaneous circular products requires a concrete mix that is wet com pared to the mixes used in dry mix processes.
Using both inner and outer forms, a cone is placed on the inner form to direct concrete down into the annular space between the forms. The concrete is then consolidated by stick vibrators or external vibrators, and the exposed top surface shaped and finished as required by hand, using edgers, trowels, and brushes.

# Figure II-4 depicts an automated vertical pipe casting operation.
Employees work from scaffolds that are rolled into place around the perim eter of the external pipe form.
As the concrete discharge chute rotates around the form, workers using shovels, boards, tampers, and/or vibrators ensure the proper placement and consolidation of the concrete.
Most concrete pipe is cast with a relatively dry, low-slump mix that is mechanically placed and consolidated in the form.
Two of the four mechanical methods use both inner and outer forms, which vibrate with either tampers or vibrators while the dry-mixed concrete is cast into the annular space between them.
In the tamping method, compaction is performed directly by vertically operated tampers.
In the dry cast method, consolidation is done by external vibration of the inner or outer form.
The other two mechanical methods use only the outer form and either spin the pipe horizontally while centrifugal forces distribute the concrete delivered by conveyor, or spin a mandrel-like packerhead that is drawn up inside the pipe as concrete is cast from above, compacting as it goes.
These four mechanical, dry-type mix methods of casting pipe are shown in Figure II--5. Metal pipe forms are placed by forklift or man ual or automated cranes onto openings in a circular casting floor.
The floor rotates (at slow speeds) to position the form in the operational packerhead area.
An employee on an elevated platform controls the packerhead spinning speeds, the up-and-down motion of the packerhead, and the flow of concrete into the form. When the casting is complete, the floor rotates an empty form into place and the forklift removes the cast pipe and mold to a curing area. per second (rps) while vibrating and depositing concrete, and at speeds up to 10-12 rps while "throwing" the concrete and compressing it against the rotating form. In the centrifugal process, excess water is removed, further lowering the water/cement ratio of the concrete.
Figure II-7 depicts one method of pipe spin-casting.
In this method, the pipe form is assembled by bolting or clamping the halves together. The form is placed by hoist onto a rotating pipe machine.
Horizontal pipe machines are usually constructed from groupings of auto/truck tires that serve to cradle and spin the form.
In this figure, the rotating force is applied by overhead tires that spin the pipe form at the required speeds. Concrete is added by a movable extruder, operated by a worker who is positioned to visually inspect the centrifugal consolidation during the placement process.
Internal finish work is usually performed by a hand-held, dowel-mounted trowel.
A worker runs it in and out of the pipe orifice while the form is spinning.

# FIGURE II-7. HORIZONTAL PIPE SPIN CASTING
Casting large miscellaneous products is similar to the tamping, dry cast, or wet cast methods used for pipe manufacture; however, the form may be square or rectangular as for burial vaults or septic tanks.

# Finishing
Wet finishing includes tasks such as screeding, floating, troweling, patching, rubbing, and cleaning surfaces not in contact with the form. Screeding is the back-and-forth motion of a strike off (a wood 2 by 4 or steel channel) resting on a screed guide to form the surface of the con crete to be finished. Workers may have to reach, bend over, and pull to perform this task.
Floating, the smoothing of the surface with a wood, aluminum, or magnesium float, is manual work requiring bending, kneeling, and reaching.
Troweling smooths and compacts the floated surface when the surface is hard enough to walk on without leaving indentations.
Additional treatment of the formed surface may take place after the form has been removed and the product has cured. This is particularly true for architectural panels, when the surface texture is important. Techniques such as grinding, bush hammering, sand blasting, water washing of retarded surfaces, or acid etching are used to produce a variety of desired architectural effects.
Bush hammering is the roughening of the hardened concrete surface with a vibrating hammer, the head of which is serrated with a series of pointed teeth. Sand blasting is the high-pressure spraying of sand onto the exterior concrete surface to clean or smooth it. Water washing (up to 300 psi) is the flushing of cement paste that purposely has been retarded in setting to expose the surface of the aggregate.
Acid etching serves a similar purpose, but does not expose as much of the aggregate.
This procedure involves the mixing, dilution, and application of muriatic acid, an industrial grade of hydrochloric acid.
In some instances, precast concrete products are cut to length or have portions removed by sawing them with a concrete saw.
This type of saw is similar to that of a carpenter's circular skill saw except that the blade size ranges from 1-3 feet (or more) in diameter.
During repetitive operations, or when using larger blades, saws may be semiautomated and suspended overhead. The power source for the concrete saws may be electricity or pressurized air, although some of the smaller, portable models may be powered by gasoline engines. Most saws are not provided with a lower (exposed) blade guard.

# Curing
Three fundamental factors in all methods of curing concrete are time, temperature, and moisture.
Within limits, an increase in temperature shortens the curing period by accelerating strength gain.
The time/temperature relationship is not the same for all mixtures, materials, and conditions and is determined empirically.

# I
The curing of many larger precast products is accelerated by radiant heat, steam, hot water, or hot oil. In some instances, the cast product is exposed to live, low-pressure steam within an insulated kiln or steam shed. Pipe or other products to be steam or heat cured will usually be transferred from the casting area to the heated shed by conveyor, forklift, hoist, or, in some instances, by rolling.
The products remain in the steam shed for 2-8 hours (frequently overnight) before being removed and the form stripped.
In some instances, the form is stripped before the product is steam cured.
Large pipe is frequently enclosed (in the place where it was cast) by canvas, plastic, or other material into which steam or warm, moist air is introduced.
Steam and hot water for accelerated curing procedures are usually generated at the plant by a low-pressure boiler and piped to designated locations prior to release into the curing shed.
Occasionally, a chemical curing compound is sprayed on the finished surface of the concrete.

# Form Stripping
Once a concrete product has cured sufficiently to be handled, it is necessary to remove it from the forms it was cast in or, conversely, to remove the forms from the product. The tasks and equipment used in form stripping operations vary considerably with the nature of the product. Reusable metal forms, such as those used during the manufacture of pipe, are usually handled by overhead hoist. The inner form is rigged to the crane and removed-a task made more difficult because the product fre quently adheres to the form surface.
In some instances, striking the form with a hard rubber mallet is sufficient to jar the concrete loose. In others, a hoist is used to shake the form and/or to pull the form free. Large pipe forms are frequently equipped with a means to collapse the internal form within the pipe bore.
Workers enter the pipe bore to release retaining clamps.
Rigging of the hoist to large form members requires that employees gain access to elevated areas. This may be done by ladder, rolling scaffolding, or climbing the form structure itself if it provides safe access. With low-slump, consolidated pipe, the mold is removed at the kiln prior to accelerated curing.
Flat products are removed from the mold by means of a vacuum lifter, or by lifting the product from the mold utilizing "lifting eyes" previous ly inserted in the product.
Girders, beams, or other large, vertical products may have side forms to be removed before the product is freed from the forms.
Bolts and other connectors are removed, and the side form panels pulled away or dropped to the ground. Some concrete products may require dismantling of the forms for re moval either because the form material will not be used again or because this is the only practical means of removing the completed product. Depending on the size and shape of the form, workers may perform the dismantling from the plant floor, from the elevated casting beds, from rolling ladder/scaffolds, or from the form itself. Workers will usually be performing their tasks on and among the equipment and material used during the form stripping process.
Prybars, crowbars, sledge hammers, and wrenches will be used to pull nails and remove the spreaders, stiffeners, and bulkhead-retaining tie rods.
Sledges and prybars will be used to force the separation of bulkheads from the product and/or other form structures.
This frequently involves workers pushing or pulling on the bar until the adherence forces release, sometimes suddenly.

# Material/Product Storage
Material storage in the precast concrete products industry follows a usage pattern typical to most manufacturing processes.
Raw materials necessary to produce the product will be shipped and temporarily stored in a yard. Usually raw materials will consist of the basic ingredients of the concrete (cement, sand, aggregate), the reinforcing materials (reinforcing steel, strand, wire mesh, hardware), and a variety of ancillary materials (blasting sand, equipment maintenance materials, etching acids, etc.) necessary for the production of a finished concrete product.
The bulk ingredients for the production of concrete may be hauled in by truck and dumped in covered bays or, in smaller plants, a convenient place on the prenises. Larger, more automated plants may yard consider able volumes of various sized aggregates and cement prior to transfer to mixers.
Cement may be bagged, palletized, and stored in weatherproof areas or it may be delivered by bulk tankers and stored in silos. These 94-pound bags of cement may be stacked higher than a worker's head, requiring access to the upper levels.
Reinforcing steel bars are usually received in banded lots of various lengths, ranging up to 40 feet or more.
Prior to cutting to required lengths, the rebars will usually be stored on the ground on cribbing material. Spooled or reeled material (e.g., wire mesh) is frequently stored in stacked rows.
The end spools are chocked to prevent rolling or shifting; second level spools are nestled in the spool interface.
Since forklifts or mobile cranes will be used to move these heavy rolls, adequate access space between rows of stored materials should be considered.
Product storage methods vary considerably with the size and shape of the product.
Small miscellaneous products are frequently produced in a variety of shapes at the same plant.
Yard areas are usually limited, necessitating multilayered stacking of the pieces.
Layers may be separated by cribbing and/or pallets to both protect the finished surface and to increase the load-bearing surface stability.
Larger and heavier shapes, such as vaults and manholes, are frequently stacked with cribbing layers between them to provide access for forklifts or rigging material.
Pipes and cylindrical products are stored in the manner described for rolls and reels. Pipes of the same size are stored in the same stack.
Again, care must be taken to allow adequate access for materials handling equipment and to prevent stack shifting. Large pipes are usually stored vertically.
Discarded products, broken pieces, metal scrap from forms, reinforcement, tie-wire, wood scrap, nails, chamfer strip, rejected hardware, concrete, forms, and the remainder of unused raw materials can be found in plants in this industry.
Many plants have a "bone yard" in which such discarded material is kept, pending burial or removal.

# Materials Handling
Materials handling operations are performed throughout all phases of the production of precast concrete products.
At the simplest (and fre quently overlooked) level, employees lift, carry, push, or pull everything from concrete debris to wood form material to smaller, finished products.
In fact, throughout the industry, manual handling is necessary to perform many of the tasks required in the production process, including: Individual, small miscellaneous products may be loaded or unloaded by hand. When several small items of the same variety are to be handled, they usually are strapped and palletized.
Larger products and concrete pipe require the use of lifting and unloading equipment.
Architectural and structural products usually are large, bulky, and heavy, requiring the use of cranes and special loading and handling techniques such as "A" frame holders and wood and metal chocking for security, for bolting to the trailer bed, and for single-product loads.
Since precast concrete products and their components are heavy by their nature, the industry makes use of a variety of mechanical devices to assist in handling and movement operations.

# a. Hoists and Cranes
For the most part, the types and varieties of hoists and cranes that are used in precasting operations do not differ significantly from those used in other industries.
However, because of the weight of the material and products being moved, crane and hoist usage may be more prevalent.
Smaller plants may use rubber-tired cranes with hydraulic booms to move material and products around the yard, onto trucks for trans port, and from the casting bed to the storage yard.
These mobile cranes are prevalent throughout the industry for movement of yarded material and products.
In most instances, the crane operator will work in tandem with other employees charged with the material rigging responsibilities.
Products may be manufactured with integral picking eyes that facilitate proper rigging and load balance.
In other instances, the rigging and hoisting will be performed on material necessitating new or single instance handling procedures.
Load weights and balance points must be identified by the workers as part of the rigging operation.
Larger, more automated plants are likely to have semipermanent work stations and fairly repetitive product design.
These plants are likely to use a number of overhead hoists. Overhead hoists may run on tracks and be located to service multiple operations in the manufacturing process. Larger overhead cranes are controlled by an operator located in the crane cab. Work stations may be serviced by smaller, 2-to 10-ton jib cranes.
Although a jib crane may be mounted on an independent vertical column, the horizontal "jib" is most frequently affixed to a vertical column integral to the plant's structure.
Employees at the work station operate the jib crane by using a wire-attached pendant control, which allows the worker to control the up/down and back/forth movements, or other functions of the crane, from the floor of the plant.
In these instances, the hoist operator is usually the same worker that performs the rigging.
He is also likely to accompany, with hands on, the load being transported to its destination.
Straddle carriers are large, four-wheeled, wide-spaced, high legged movers that straddle large products (such as girders, planks, or other structural elements) pick them out of forms and move
them. This open-framed machine, basically square in configuration, hoists and carries the load within a large open bay between the four wheels on which it travels. The operator's cab is located on the extreme left-hand side between the front and rear wheels. Loads suspended in the bay often obscure the driver's view of the right side wheels.
The machine ordinarily moves at about 2 miles per hour (mph) and has a maximum speed of about 10 mph.

# b. Forklifts
Many of the palletized raw materials and finished products used in precast plants are moved by forklifts.
Fork extenders may be used to increase the bearing surface of the forklift.
In some instances, a jib may be added to the forklift to convert it to a small, movable crane.
Pipe and other circular products are moved by forklifts with specially designed long forks or fitted forks with curved surfaces to cradle the product. Some forklifts are equipped with clamping forks used for attaching to and moving forms or other compatible shapes.
The power source on forklifts is most frequently propane or diesel fuel.

# CHAPTER III IDENTIFICATION OF THE SAFETY HAZARDS AND DEFINITION OF THE PROBLEMS
This chapter is divided into two major areas of emphasis: the development and presentation of data pertaining to injury incidence rates for the precast concrete products industry (SIC 3272), and the identification of those tasks performed that are hazardous to the worker.
Additionally, an estimation of the cost of injuries sustained by workers in the precast concrete products industry is presented.

# A. Injury and Illness Incidence Rates
The yearly compilations of occupational injury and illness data, prepared by the BLS, show that between 1976 and 1980, the precast concrete products industry had an average incidence rate of about 23 cases per 100 employees (Table III-l) .
In comparison, the incidence rate for all private sector industries averaged about 9.2 during the same interval. Workers in the precast concrete products industry have been consistently injured at a rate nearly 2.5 times the national average. Also, between 1976 and 1980 the average incidence rate for all durable goods manufacturing industries (which include SIC 3272) was about 14, which is substantially less than the rate for manufacturers of precast concrete products (Tables III-l and III-2).  The incidence rates for precast concrete products are among the highest rates within the manufacturing sector (top 3%). A representative selection of the manufacturing industries is shown in Table III
Table III-3 demonstrates that the occupational incidence rate per 100 employees in the precast concrete products industry was higher than those for concrete block and brick manufacturers and ready-mixed concrete, which exhibited incidence rates of 15.8 and 13.7, respectively.
The incidence rate for concrete products was also substantially higher than for blast furnaces and steel mills (9.5), which is a heavy industry involving additional injury potentials attendant to the handling of molten metal.
The severity of injuries sustained by employees of the precast concrete products industry was also shown to be high.
The lost workday cases and lost workdays incidence rates, represent a general measurement of the seriousness of occupational injuries and illnesses.
The lost workday cases incidence rate for the precast concrete products industry (SIC 3272) in 1980 was reported by the BLS as 10.4 (Table III
-l).
This figure ranged from a reported high of 12.1 in 1979 to a low of 9.1 in 1976, with an average of about 10.7 for the years between 1976 and 1980 (Table III
-l).
The lost workday cases incidence rate for all private sector industries in 1980 was reported by the BLS as 4.0  and for the durable goods manufacturing industries as 5.6 (Table III
Furthermore, for every 100 employees in the precast concrete products industry in 1980, a total of about 158 days were lost due to disabling injuries and illnesses (Table III
-l).
The Although the estimates of direct costs of worker injuries are not precise, they do reflect the magnitude of the problem.
Estimates derived from National Safety Council  data indicate that full costs of work-related accidents are more than 3.4 times the direct wage loss and medical expense costs.
Since the indemnity payments are normally less than wage loss, the real accident costs for the precast concrete products industry are estimated to exceed $105 million per year (3.4 x $30.9 million).
In addition to medical and indemnity expenses, estimates of the real cost of accidents include:

# C. Identification of the Hazards
The preceding section of this chapter defined the magnitude of the safety problem in the precast concrete products industry.
The next step in a systematic approach to effectively lowering worker accident/injury exposure is the identification of how workers are injured while performing the tasks required to produce precast concrete products.

# The Supplementary Data System (SDS)
Currently, occupational accident and injury information from participat ing states, which is taken from employers' first report of injury forms,  ' Production workers comprise about 77% of the total work force for this industry . Seventy-seven percent of the reported 1977 employment figure of 67,300 (Table III-l) is 51,821 production workers.
Compensation losses of $30,855,454 divided by 51,821 production workers yields about $595 per production worker. is compiled and reported by the BLS Supplementary Data System (SDS) . The SDS is intended to alert users to patterns and relationships of injury causal factors.
The information is entered into each of four major groupings: The frequency and percentage distribution of the injuries reported to SDS by the precast concrete products industry for the years 1976 -1979 are presented in Table III-4 for each of the groupings mentioned above. The percentages do not indicate that one category represents a greater hazard than another, since data clarifying worker exposure are not available.

# Accident/Injury Analysis
The SDS data are limited when used in the analysis of a specific industry because the "source of injury" category contains subcategories which do not apply to the industry under study, and does not contain subcategories which are related to industry-specific tools and equipment.
Further, the "source of injury" reported is the object most responsible for causing the injury.
Thus, if a worker falls from a ladder and fractures his leg on the plant floor, the "source of injury" is the floor, which probably contributed little to the actual cause of the accident.
Despite the constraints, the SDS data reported by the precast concrete industry for 1976 -1979, which included 15,208 injuries, were analyzed to identify specific industry hazards.
The analysis included 37 categories that identified injury sources within precasting operations.
The results of the cross-analysis of the SDS data are summarized in Table III
The total number of accidents/injuries appears in the "Source of Injury" column.
The numbers associated with "Type of Acci dent," "Nature of Injury" and "Body Part" do not agree with the "Source of Injury" totals since the figures given are merely the most frequent subcategories.

# Analysis of Accident Case Histories
For a more complete understanding of accident/injury causal factors, full text copies of employers' first report of injury forms filed by SIC 3272 industries were requested from all 50 States.
In most instances, the state agencies were not able to provide information.
However, 10 States 1 did provide copies of 2,250 first report of injury forms from California, Hawaii, Iowa, Kentucky, Michigan, Montana, Maryland, Washington, Wyoming, and Vermont.  Of the 2,250 accident/injury reports, 1,319 (about 59%) were included in the analysis.
Of these 1,319 injuries, 34 resulted in a fatality.
Those reports not included in the analysis primarily contained injury information, and were found to contain insufficient data to determine accident causal factors.
A preliminary analysis of these accident case histories was performed to determine whether the accident data base was indicative of accidents occurring to workers in precasting operations nationwide.
Each report was categorized by type of accident ("struck by," "caught between," "fall").
Numerical and percentage values of the "type of accident" categories were compared to the national SDS figures (Table III-4). The comparison (Table III-6) shows markedly similar ratios; e.g., the percentage of "struck by" and/or "caught between" accident types are reasonably consistent in both data bases.
Because of the similarities between data from the sources considered, it was concluded that the accident/injury case histories used in this report are representative of accidents that occur to workers in the precast concrete products industry.
The first step in the analysis was the identification of the specific task, tool, type of material, piece of equipment, or plant area most closely associated with the accident in each case.
This procedure made possible more precise and industry-specific classification than the SDS "Source of Injury" category could provide. Then, a causal factor was identified in each case (e.g. improper tool use, lack of personal protective equipment, lack of adequate guarding, improper materials handling procedures).
The task/tool/equipment factors and accident causal factors were then cross-indexed to allow the identification of problem areas.
The following narrative descriptions of how workers are injured in the precast concrete products industry are based on analysis of SDS data (Table III -5) and the accident case histories. The percentage that follows each category or factor is the percentage of the total number of accidents (1,319) from the case history analysis.
Section a covers general accident factors; i.e., tasks, tools and items of equipment that are not specific to the precast industry.
Section b presents factors that are specific to precasting processes.
Section c describes accident causal factor patterns, groups of factors which may encompass several task/tool/equipment categories. Essentially, the organization of sections a, b, and  is followed in the presentation of the recommendations in Chapter IV.

# a. General Accident Factors
The following narrative paragraphs describe the ways workers are injured due to task/tool/equipment factors which are not necessarily specific to the precast concrete products industry. Although these general factors are arranged in order from highest to lowest percentage of occurrence, this grouping does not suggest that one factor represents a more significant hazard than another, since no data clarifying worker exposure are available.
(1) Materials Handling (28.0%) (a) Manual (19.9%)
(i) Lifting (9.6%)
The act of lifting items resulted in nearly 10% of the injuries in the industry. Approximately 81% of these incidents involved overexertion to the back while manually handling materials.
Loss of grip accounted for 9% of the lifting accidents. These usually resulted in injuries either to the lower extremities when the load was dropped or to the fingers when the load was set down with inadequate clearance.
(ii) Mechanical Materials Transport (7.1%) This category presents a variety of tasks associated with materials handling as well as a variety of other accident causal factors.
Included in this activity are interface of manual and mechanical load handling procedures performed on flatbed trucks and the manual transfer of materials to forklifts. Manual materials handling and gripping of materials accounted for 27% of the injuries in approximately the same causal/injury breakdown as cited in the discussion of the lifting category. Improper stacking and binding of materials was reported to be the cause of about 27% of these accidents, usually from the material falling onto the worker.
An additional 12% of the accidents occurred to workers attempting to climb onto the transport vehicle or the material itself when access was not provided.
(iii) Carrying and Holding (1.8%) This category of activity includes the manual tasks, by one or more workers, of carrying or handling materials.
Many of the injuries were sprains and strains that usually occurred from overexertion during the procedure.
About Hand operation of the hoists necessitated close proximity to the hoisted loads and contributed to employee exposure to hoist or rig failure.
(iv) Conveyors (0.6%) Although only 0.6% of the accidents involved con veyors, they accounted for nearly 9% of the fatal injuries.
These accidents occurred when the conveyor jammed and the operator/worker attempted to free the jam without deenergizing and locking out the system.
Workers were caught by or in exposed moving portions of the conveyors.
Lack of guarding of exposed moving parts and/ or nonlimiting access to the area were cited as contributing factors to the accidents.
Similarly, the nonfatal incidents usually involved the upper extremities being caught in or between the conveyor mechanisms as shown in Table III In the latter accidents, the injured workers were in the path of travel of the loaders and were either caught between it and another object or they were run over by the moving equipment.
Inaudible or nonfunctioning backup alarms as well as operator inability to see coworkers were cited as contributing factors.
(2) Handtools (11.5%) (a) Handtools, Powered (5.8%) Nearly all of the injuries attributable to the use of powered handtools resulted from deficiencies in three areas: guarding, tool usage, and lack of eye protection.
The injury analysis revealed that most eye injuries occur during use of grinders. The remaining grinder-related accidents were the result of inadequate or non-existent guards that failed to prevent finger contact or protect against stone disintegration.
In some instances, while using the grinder, part of an employee's body, usually the thigh, came into contact with the abrasive stone.
In the SDS accident/injury analysis (Table III-5), eye injuries occurring during grinding activities were not listed with grinders; rather, they were tabulated in the "Particles" category.
Although lack of eye protection contributed to 20% of the powersaw injuries, the single, consistent accident causal factor was inadequate or nonexistent saw blade guards (58%).
Included in this category were instances when anti-kickback devices were not used during ripping operations. The majority of injuries resulting from lack of saw guards were lacerations and amputations of fingers.
Two eye injury accidents also occurred while using concrete saws.
The accident analysis shows that most accidents during drilling tasks occurred when large-diameter (1-inch or larger) holes were drilled through forms.
The drill bit would bind and the drill motor would continue to turn, catching the workers' hands between the motor and adjacent items, usually the form. This may be interpreted as improper tool use or as improper worker position relative to the task. Lack of eye protection accounted for one-third of the reported injuries that occurred while using airhammers. In some instances, airhammers were used in awkward positions, resulting in strains and sprains of the back and/or arms.
In three instances, the airhammer was positioned for use too close to the edge of either a form or product, and the worker's hands or fingers were caught. Table III-5 indicates that powered hammers as a source of injury resulted in injuries to the back because of worker overexertion and to fingers that were struck by the hammer. The injury reports indicated that many injuries were associated with over loading the shovel, twisting the body, and handling the load from too great a distance (see Table III-5, "Shovel" and "Concrete aggregate"). The activity of "prying" is frequently performed by workers dismantling forms and separating the product from the form.
Referring back to Table III-5, 47% of the accidents involving crowbars, a tool routinely used for prying, were classified by the SDS as "struck by" accident types resulting in contusions and sprains and strains.
The most frequent areas of the body injured were the back and finger.
The analysis of the accident cases showed that 65% of the prying accidents were reported to be caused by improper worker position relative to the task. When the prying implement slipped, the tool usually either struck the worker or the worker slipped and fell.
Most of the remaining accidents involving prying activities resulted from improper tool use. Shovels were commonly misused by workers attempting to pry forms loose from cured concrete.
The most common type of accident that occurs during the use of handtools is the "struck by" variety (Table III-5), most frequently caused by improper position of the worker relative to the task.
The analysis indicated that glancing blows are commonly cited as the cause of the accident.
Fingers and hands were struck by hammers and sledge hammers when part of a worker's body was in the path of the deflected hammer movement.
Use of improper tools contributed to 25% of the hammering accidents. Typical cases involved shovels, wrenches, and boards used to hammer forms, nails, or other materials.
The analysis indicated that fingers were the most frequent part of the body injured while using a wrench; usually, the wrench slipped off a nut or bolt.
The injury reports indicated that many accidents associated with tool slippage were caused by improper tool usage (size and/or adjustment).
The accident probability was compounded by improper worker position relative to the task.
The information in Table III-5 indicates that workers suffered sprains and strains from excessive physical effort while using wrenches. This could possibly be a result of using wrenches of improper size for the job.
(3) Worker Proximity to Operations (7.4%) (a) Walking Through Work Areas (6.3%)
In a number of instances a specific task or activity description was not included in the accident report. The worker was "walking" in an unspecified section of the plant. Almost 29% of these injuries were nail punctures of the foot. More than 45% were falls to the working/walking surface caused by slipping on wet, slippery surfaces or tripping on material, usually pieces of concrete debris, rebar, welding stubs, or leads.
(b) Working Near Operations (1.1%) This category includes workers injured by tasks or operations that were independent from their assigned tasks.
The most prevalent accident/injury in this grouping was flash burns from nearby welding operations. In fact, 45% of the reported flash burns occurred to workers who were not involved in the actual welding process. Two workers were also injured by particles from nearby metal grinding operations.
(4) Welding, Cutting, Burning (4.6%)
The data indicated most of the injuries (54%) that occurred in welding, cutting, and burning activities were typified by foreign bodies in the eye that were caused by slag or weld "pop."
In these instances, the workers were not wearing eye protection.
An additional 20% of the injuries were flash burns to the workers performing the welding operations.
In these cases, the worker was usually inadequately protected because cutting goggles were being used instead of approved welding hoods during short welding operations.
The SDS data (Table III -5) indicate that welders flash burns account for 1% of the industry's injuries.
(5) Chemical Handling (4.6%) More than 44% of the incidents in this category involved chemical dermatitis caused by direct skin contact with moist concrete.
Concrete burns, most commonly to hands and forearms, were usually sustained during casting or cleanup operations.
In a few instances, concrete dermatitis developed during the dry mixing of the concrete.
Lack of respiratory protection accounted for four of the incidents involving cement dust.
Lack of personal protective equipment, mostly eye protection, was a contributing factor in 30% of the chemical handling injuries.
Workers received eye injuries during mixing, casting, and cleanup operations.
Lack of eye protection was also a causal factor in four eye injuries that occurred during spray application of form release agents.
Sprayers were overpressurized by misapplication of unregulated systems, resulting in explosions of the canisters in two instances. Analysis of the accident data indicates that 46% of the materials storage accidents were the direct result of improper stacking and/or binding procedures.
Product storage (multi level) stacks were not stable enough to support their height and weight. Most of the injuries occurred while workers were in the process of adding additional material to the stack. The second most frequent cause of injury in materials storage activities was related to manual materials handling and improper gripping of the load. Fingers and toes were most at risk during these activities.
(7) Ladders and Scaffolds (3.9%) One-fourth (25%) of the ladder/scaffold accidents were directly attributable to working from makeshift platforms (improper tools).
The accidents that occurred on makeshift scaffolds were usually falls to the level below. Two scaffold accidents (one fatal) involved scaffolds with inadequate or nonexistent guardrails.
Slippery (wet, icy) conditions on the ladders/scaffolds were cited in more than 22% of the accidents, mostly resulting in falls to the working surface of the scaffold.
Inadequate securing of ladders against slipping (chocking, blocking, or tying) caused six of the accidents that were falls to levels below.
In two instances, ladders were placed in the paths of moving vehicles (forklift, crane), resulting in collisions and serious injuries. The majority of injuries that occurred to workers cleaning forms, products, or mixers probably would have been prevented by eye protection.
The second largest accident causal factor in chipping/cleaning tasks was inadequate or nonexistent access to the area; makeshift worker platforms were common.

# b. Process-specific Accident Factors
The following narrative paragraphs describe the ways workers are injured due to task/tool/equipment factors specific to the precasting processes.
In the absence of data clarifying worker exposure, the percentage ranking is not intended to imply that any one factor represents a more significant hazard than another.
(1) Form Work (7.2%) (a) Form Assembly/Disassembly (4.9%) Form assembly and dismantling are frequently manual procedures that involve physical manipulation of form components.
Consequently, the accident/causal factors associated with form assembly primarily fall into the categories that typify physical procedures; e.g., the worker's position relative to the task, and gripping and handling form components.
Many of the injuries that occurred in form assembly tasks were sprains and strains of the back, and injuries to the fingers.
In two instances, workers were struck by form sections being turned by overhead hoists.
Inadequate chocking and bracing of form sections during assembly or stripping contributed to many of the more serious injuries.
In the instances when the form component adhered to the cured concrete, workers were struck by or caught beneath a portion of the form that was suddenly released and fell. Additional information concerning injuries resulting from form work can be found in Table III Binding and unexpected release of the inner cores or outer forms of pipe molds typified most of the accidents in this group.
"Caught between" accidents resulting in injuries to the fingers were the most common.
(r.) Form Stripping (1.2%)
The most common cause of accidents in form stripping activities involved improper tool usage. Most frequently, these accidents resulted from using shovels as levers to pry form walls loose from the cured concrete.
The most serious accidents, one of which was fatal, involved inadequate or nonexistent cribbing or blocking of form walls.
The fatality resulted when a worker crawled under a portion of form wall no longer integral to the remainder of the form or the product to determine where the form was still "hung up." The form wall fell while the worker was under it. Additional injury information is contained in Table III
-5, "Reinforcement". (b) Stressing (1.5%)
The accidents that most frequently occurred during stressing operations were similar to accidents which occurred during other forming and casting operations. Lack of eye protection accounted for more than 32% of the incidents-most of these caused by metal particles (scale) flicking off during the handling of the strand. The more serious accidents occurred during the actual stressing procedure and involved inadequate or nonexistent means for controlling employee access to the stressing area.
The high tension stretching of the steel strand poses a somewhat unique hazard to the industry.
Since stressing is used in only about 10% of the precasting plants, the relatively small number of accident cases (19) may not reflect the frequency of accidents occurring in the actual stressing operation.
The static forces contained in stressed strand are potentially hazardous. When these forces are accidentally released, workers within range of strand whiplash are exposed to potentially serious injury.
(c) Metalworking Machinery (1.3%) Metalworking machinery (cage rollers, rebar benders and cutters, press brakes) are used in the precast concrete products industry to manufacture the shapes necessary for reinforcing concrete. More than 1% of the accidents that occurred to precast concrete workers happened during metalworking tasks related to the production of the reinforcing steel shapes.
Inadequate and nonexistent guarding was the major accident causal factor associated with metalworking tools and operations.
Cage rollers (0.6%) accounted for nearly one-half of these accidents. Failure to guard in-rolling nip points on the cage rollers resulted in two of the more serious injuries. Other accidents occurred while handling the metal items during bending, cutting, or rolling operations. Frequently, these were either lacerations of the hands caused by sharp edges or crushing injuries due to hands-on manipulation of the metal while the machine was in operation.
Additional information concerning injuries from machinery can be found in Table III-5.
(3) Oiling Analysis of the accident reports failed to identify accidents which were specifically ascribed to the oiling process. Factors which may influence the occurrence of accidents during oiling procedures include contact with form release agents, access to forms or product, and working/walking surfaces. These factors are discussed in the paragraphs on Chemical Handling in section a, and in the paragraphs on Personal Protective Equipment, Access, and Working/Walking Surfaces in section . Failure to lockout or tagout an energy source before entering or reaching into concrete mixing equipment accounted for 25% of the accidents involving concrete mixing and 3 of the 6 lockout/tagout related fatalities. Twelve percent of these accidents occurred when workers were attempting to access mixers.
Fifteen percent of these accidents involved workers who were caught in or struck by chutes or hatches when they were not secured in place.
(b) Concrete Transport (0.8%) Ready-mix concrete delivery trucks accounted for most of the accidents in this category.
Usually the worker was struck by or caught between the delivery chute and the form.
The more serious injuries happened during cleaning/maintenance operations on the trucks and were caused by lack of adequate energy control procedures. The accidents that occurred during casting operations were most commonly caused by lack of access to the casting beds or between forms. Workers must continually get up onto and down from forms, or move back and forth between forms.
In these instances, access was either not provided or was located in an area away from the work activity.
Slipping or tripping on working surfaces caused almost 24% of the casting accidents. Most of the accidents were falls from or onto the casting bed, or involuntary recovery from slips or falls resulting in sprains, fractures, and contusions. Accidents that were more task or tool specific (concrete delivery, pipe machine, scaffolds), yet still operationally part of the overall casting procedure, were included in the more specific category.
(b) Concrete Buckets (0.5%)
The injuries occurring to workers using concrete buckets were caused by the opening and closing mechanisms on the bucket's pour hatch. The latch bar frequently caught fingers and hands between the handle and the bucket.
(c) Pipe Manufacturing Equipment (0.4%)
The serious injuries to workers during mechanical pipe operations (packerhead and horizontal pipe spinning) were the result of inadequate machine guarding or isolation of the operation and the moving mechanical parts. A packerhead table with a gap between the table and the adjacent working surface caused a serious leg injury. Inadvertent entanglement with a horizontal pipe spinner injured another worker. Workers' eyes are also at risk in these operations.
The rotating speeds used in these casting operations tend to "throw" cement and aggregate out into the adjacent work area. This classification of equipment is comprised of various types of trucks (flatbeds, pickups) that are used to transport products on or off of the plant premises. More than 82% of these accidents occurred while workers were attempting to get onto or off of the vehicle bed (access).
The beds of these vehicles are typically 3   The most serious accident occurred when a crane was used to lift a product from a form to which the product remained adherent. When the crane attempted to hoist the product, the weight of the adhered form, an unknown force, resulted in crane overload and failure.
One worker was killed.
Inadequate cribbing or blocking of the product during product removal tasks also resulted in serious injuries to workers (one was fatal). Workers under the product attempting to position rigging material or guide the load were injured when the product shifted, catching them under the load.
(c) Rolling Stock (Pipe) (0.8%) Handling and storage of rolling stock (concrete pipe) resulted in 0.8% of the injuries in the industry.
More than 55% of these accidents were the result of improper or nonexistent binding or chocking of the pipe. Although the back, hands and fingers were the most frequent parts of the body injured, the lower extremities were more seriously injured.
Most of the remaining accident case histories cited rigging failure during stacking as the cause of the accident.

# c. Accident Causal Factor Patterns
The method used to analyze the accident case histories allowed the identification of significant accident patterns by the grouping of related accident causal factors.
For example, injuries attributed to wet, icy, or slippery surfaces; tripping; or puncture; are discussed below under the general heading "Working/Walking Surfaces."
These accident patterns indicate hazardous activities or conditions that encompass various tasks, industrial processes, tools, and items of equipment utilized in the precast concrete products industry. The arrangement of these patterns by percentage, in order from highest to lowest, is not intended to suggest that one accident pattern represents greater hazard to workers than another pattern, since data clarifying worker exposure are not available.
(1) Manual Materials Handling (17.6%) There are two major accident types that occur as the result of improper manual materials handling procedures: overexertion accidents that cause sprains and strains of the back and shoulders, and materials movement accidents (dropped load, load placed on fingers) that usually result in lacerations, contusions, and fractures of fingers or toes.
There is very little task specificity in manual materials handling accidents. Workers are required to lift and handle materials and tools throughout all precasting operations.
They appear to be injured in proportion to the expected amount of manual materials handling likely to be used in any given task.
(2) Working/Walking Surfaces (12.4%)
The production processes of forming, pouring, stripping, and cleaning forms produce water, excess concrete, forming material, and a variety of tools and equipment that clutter walking and working surfaces.
These hazards result in worker falls to the working surface and/or involuntary recovery injuries (sprains and strains that happen when a worker attempts to recover his balance).
The SDS data (Table III-5) indicate that bodily motion (not including lifting, pushing or pulling) was the source of injury in 5% of the industry's accidents. Additionally, working surfaces were the source of injury in 12% of the accidents when workers fell while performing their duties.
Workers in form stripping operations (most likely responsible for exposed nails) are not the individuals usually injured by nails.
The pattern of accidents related to nail puncture indicates that frequently (56%) it is a person walking through the area who steps on an exposed nail.
Table III-5 indicates that nails were involved in 1% of all injuries, resulting most frequently in punctures to the foot.
(3) Personal Protective Equipment (10.7%)
The lack of personal protective equipment is not, in itself, a cause of accidents.
However, during activities associated with some tasks or tools, workers are exposed to hazards likely to result in injuries. For example, cutting torch tasks cause metal particles to fly through the air, increasing the probability of eye injuries; or, mixing and placement of concrete may result in material splashes that cause eye injuries; or, loads may fall or be dropped onto workers feet resulting in toe injuries.
In precasting operations, 10.7% of the injuries were likely to have been prevented by the employee wearing proper personal protective equipment.
In most instances resulting in injury, the type of protective device found lacking was eye protective equipment.
Concrete splashes, slag from cutting operations, metal particles from grinding, sawdust, particles falling from or blowing off forms, curing compounds, and general airborne dirt all resulted in eye injuries.
Although safety glasses (eye protection) may not have prevented all of the reported injuries, their use certainly would have lowered the incidence of occupational eye injury.
Two fatal accidents in this category involved employees working from elevated areas and were directly attributable to the lack of fall protective devices.
In both cases, the workers were performing tasks, on or from forms, without the protection of a safety belt and lanyard.
The use of an adequate scaffold, including guardrails, would also have provided worker protection.
Crushing injuries to toes and feet resulting from the impact of heavy products and materials are not likely to be entirely eliminated by the wearing of safety-toed boots. However, such protective footwear would likely have prevented some of the injuries and reduced the severity of others in many of the cited instances.
(4) Access (9.8%) Inadequate or nonexistent access to work areas was the primary causal factor in 9.8% of the accidents. As an accident causal factor, lack of adequate access resulted in workers being injured while performing most tasks and activities directly involved in the manufacture of precast concrete products. Workers attempting to move or work on casting beds and/or forms accounted for 38% of the "access" accidents.
Most of these accidents were falls to lower levels; that is, off of the form or casting bed and onto the adjacent working surface (see Table III-5, "Working/walking surfaces"). Injuries ranged from simple bruises and lacerations to fractures. Many of the remaining "access" accidents were related to equipment; more than half of the vehicle access accidents involved workers climbing onto or down from truck beds. Again, the injuries usually were caused by falls to below.
(5) Mechanical Materials Handling (7.6%)
Mechanical materials handling accidents comprised 38% (13) of the fatalities analyzed; half of these occurred to coworkers that were struck by a moving vehicle (crane, forklift). Twenty-three percent of the fatalities in mechanical materials handling were caused by rigging overloads. There were two incidents of crane "two-blocking" that resulted in fatal injury to workers.
The use of hoists, cranes, and forklifts is common throughout the industry.
In many instances, the product is simply too heavy to move by other means.
In some instances, the material is also too heavy to be moved by the selected mechanical method.
Employees frequently work in close proximity to moving equipment.
This interface, man and moving equipment, when compounded by the distractions of ongoing work and background noise, contributes to fatal accidents in precasting operations.
(6) Guarding (2.7%) Inadequate or nonexistent guards were cited in 2.7% of the accidents.
All but 2 of these 36 accidents occurred in con junction with exposed moving parts of machinery and/or tools. Unguarded saws injured workers most frequently (31%), and un guarded grinders (abrasive stone) accounted for 17% of the injuries related to guarding. Conveyors may jam during operation.
Workers were injured while attempting to remove the jammed objects without first controlling the systems' energy sources.

# D. New Employee Injury Rates
Analysis of the 1,319 accident case histories shows that 513 (54%) of the 950 reports that included length of employment information involved workers employed less than 1 year.
In fact, 408 (43%) of the injuries were actually sustained by workers employed for less than 6 months.
Several factors may influence the apparent prevalence of injuries to new employees. Although some plants experience a relatively high turnover rate, many smaller plants seem to have a stable work force.
These plants will layoff and rehire the same workers in accordance with seasonal or economic demands. Therefore, an injured employee reported as "new" on an injury report form, may actually be an experienced worker.
Further, new employees may perform the more hazardous tasks.
Or, new employees may typically comprise about 50% of the work force.
No information which identifies either the distribution of tasks among workers of varying experience or the number of relatively new employees that make up the worker population at any given time is available.
However, there is evidence to suggest that new employees or employees performing new tasks suffer significantly higher rates of injury than the employed population in general .

# E. Summary of the Problem
Accident and injury statistics for 1980 indicate that the injury and illness incidence rate for the precast concrete products industry (SIC 3272) was 2.5 times the rate for all private sector industries. Not only does the precast concrete products industry have the problem of high injury incidence rates relative to all private sector industries, but within the manufacturing sector where there are similar tasks and operations, only 8, or 3.4%, of the 235 four-digit SIC code industries had higher incidence rates than this industry in 1980.
Analysis of 1,319 accident case histories has demonstrated how employees in the precast concrete products industry are injured while performing those tasks necessary to manufacture concrete products.
Furthermore, patterns of accident causal factors common throughout the industry have been identified.
It is concluded that the primary safety needs of the precast concrete products industry are:
1) implementation of the recommendations for safe work practices presented in Chapter IV; and 2) implementation of a safety management program, such as the one presented in Chapter V.

# CHAPTER IV RECOMMENDATIONS FOR SAFE WORK PRACTICES FOR THE PRECAST CONCRETE PRODUCTS INDUSTRY
The safe work practices recommended in this chapter are presented as ways to reduce and control injuries resulting from precasting operations. The hazardous tasks identified, as well as the patterns of accident causal factors developed in Chapter III, indicate potential problem areas that have been given insufficient emphasis by the precasting industry.
The solutions offered in the following safety recommendations may not be entirely suitable for a specific plant.
In some instances, management may even view the recommendations as counterproductive to their operations. In these instances, the responsible persons (plant managers, safety managers, and/or plant owners) should interpret and modify the recommendations to make them applicable to their specific needs.
It is essential that, in any modification of the recommended safe work practices, a similar quality of worker protection be provided.
Considerable emphasis has been placed on the safety recommendations directed at hoist and crane activities.
In the cases analyzed, 41% of the fatal accidents occurred due to misuse of hoists and cranes.
Expertise specific to hoisting equipment may be less developed than supervisory expertise particular to production; therefore, hoist and crane safety has been presented in detail.
The goal of this study has been to identify hazards in precasting opera tions and to recommend applicable and manageable means to alleviate them. The safety recommendations presented are not meant to be all-inclusive or to supersede the OSHA General Industry Standards, which offer adequate regulatory guidelines for many of the tasks, tools, and equipment used in the precast concrete products industry.
Emphasis has been placed on recommendations for safe work practices which address tasks, activities, and tools commonly associated with injuries. This preliminary section presents safe work practices for the tasks, acti vities, and tools that are commonly used throughout precasting operations. Included in this section are the recommendations for manual and mechanical materials handling, handtools, worker proximity to operations, welding and cutting, chemical handling, ladders and scaffolding, and chipping/cleaning.

# Manual Materials Handling
A wide range of manual materials handling activities are inherent to the precast concrete products industry.
Workers may be required to lift, carry, push and pull raw materials and/or finished products during loading/unloading, processing, storage and cleanup operations.
The handling and manipulation of loads can markedly increase the stresses imposed on workers' musculoskeletal systems and increase the likelihood of injuries to certain body areas (e.g. back, extremities) .
The application of proper handling techniques can minimize these stresses and help reduce the incidence of musculoskeletal injuries.
A number of factors can directly influence the likelihood of an individual suffering a musculoskeletal injury during the performance of manual materials handling activities.
These are discussed in NIOSH's "Work Practices Guide for Manual Lifting"   The proper use of safe handling techniques by workers performing manual materials handling activities is one of the most important factors in avoiding injury, since the techniques reduce body stresses and their application are at the discretion of the worker.
NIOSH's publication "How to Lift Safely"  illustrates several of the important points in materials handling.

# Key points include:
- Workers should assess the size, shape and weight of objects to be lifted or carried. Objects deemed to be beyond the physical capacity of one worker should be handled by two or more workers. o Workers should spread their feet apart to provide a wide base of support during manual materials handling, o When lifting objects, workers should bend their knees to a degree which is comfortable to them and then get a good firm grip on the item to be lifted. Lifting should be accom plished through the use of leg muscles in straightening the knees rather than using the back muscles, o Workers should handle objects as close to the body's center of gravity as possible, o Workers should avoid twisting the trunk when handling ob jects.

# b. Assistive Devices
A number of assistive devices can reduce or eliminate the need for stressful manual materials handling. For example, rebar can be stored on surfaces which correspond to the height of the bending and cutting machines so that the worker does not need to lift the rebar from the floor level to the cutting or bending surface.
It is even better to have the rebar storage surface gently slope toward the cutting and bending machine.
This reduces the stress required to pull the rebar to the cutting or bending position.  .
These methods also represent a wide range of costs to employers under various financial restraints. Training programs are means of conveying information to workers. A goal of training programs is that workers will alter their work habits by substituting safer work practices for various unsafe techniques. This form of behavioral modification usually requires feedback to the workers.
Supervisors and employers must take the time to positively reinforce safe practices and constructively criticize unsafe practices. Effective training is approached as an ongoing interaction among all plant employees and not a one time exposure to the training material .  o Approved boom stops installed to preclude travel beyond the angle of 85 degrees above the hori zontal plane  o Boom angle indicators for booms capable of moving in the vertical plane  o Automatic devices to stop boom drum motion when the maximum permissible boom angle is reached  o Boom length indicators for telescopic booms  o Automatic "anti-two-blocking" devices for hydraulic extending booms  o An effective audible warning signal (horn) mounted outside the cab with controls easily within reach of the operator  o A spirit level at the outrigger controls for level ing  o Adequate lighting for night operation, including backup lights for mobile units  o Wheel chocks on mobile units to block movement on slopes when the equipment is left unattended or is undergoing maintenance  o A fire extinguisher and a first-aid kit  o Rearview mirrors on both sides of mobile equip ment  o Self-closing filler caps and flame arresters on fuel tanks  o Slip-resistant material on crane surfaces subject to foot traffic .

# Mechanical Materials
(c) Equipment should be safety inspected frequently (daily to weekly). Inspectors should :
- Check brakes, clutches, and safety devices for prop er adjustment and operation (if possible, check load brakes by lifting a capacity or near capacity load a few inches off the ground) o Daily, visually inspect each component of the equip ment used in lifting, swinging, or lowering the load and components used to lift and lower the boom, for any defects that might result in unsafe operation o Check for freedom of rotation of all swivels o Check all functional, operating mechanisms such as sheaves, drums, brakes, locking mechanisms, hooks, boom, jib, hook roller brackets, outrigger compo nents, limit switches, safety devices, hydraulic cylinders, instruments, and lights o On cranes, daily, visually inspect the boom and jib for straightness and for any evidence of physical damage such as cracking, bending, or other deforma tion of the steel elements or welds (this precau tion is especially important on lattice and tubular booms, where every component should be straight and free from dents) o Inspect wire ropes (including standing ropes), rig ging hardware, and attachments o On cranes, check that the counterweight is secure and that the weight and capacity are permanently and legibly stamped on jibs, blocks, equalizer beams, and all other accessories o Daily, visually inspect the equipment for fluid or air leaks o Ensure that all walking surfaces of the equipment are clean and free from tackle, grease, and oil.
(d) All capacities listed on the load chart for machine "on outriggers" and "on tires" are based on the crane being level and on solid support. The importance of leveling cannot be overemphasized. The manufacturers' capacity tables should be referred to for both outriggers and tires, since lifting capacity is reduced markedly when the crane is not level .
(e) If a crane has to make its lifts on rubber, always use wheel chocks to block the wheels and apply the airbrakes to hold the crane in position.
If the machine is of two-engine design, keep the carrier engine running to maintain air pressure.
Ensure that the tires are properly inflated; if they are not, then the capacity and crane stability will be reduced .
(f) Dunnage under outriggers must be strong enough to support the imposed load.
If more than one layer is needed, then proper "cross-hatched" stacking must be used to prevent tipping.
Reset outriggers before a lift if necessary.
If floats are allowed to settle into the ground, they lose their effectiveness, making continued operation unsafe .
(2) Competent operation of equipment (a) Only thoroughly trained and tested workers are permitted to operate a crane.
When an operator is assigned to a new crane, competence with that crane must be demonstrated.
Training and testing must be sufficient to demonstrate that the operator fully understands and is capable of safely performing all tasks.
The testing should include a performance evaluation of: o Never allow his attention to be diverted from the operation of the crane (coworkers should not be per mitted to talk to the operator while he is working) o Allow no passengers (excepting an oiler) on a crane in motion or operating, especially during mobile yarding operations o Not back up the machine without first making certain that no one will be endangered (when vision of the area behind the crane is blocked, use a signalman) o Sound an audible alarm (horn) before moving a crane and whenever the crane is approaching other workers o Sound an audible alarm whenever a suspended load is approaching employees to give them time to move o Never operate the crane within 10 feet of energized high-voltage powerlines.
(c) During operations, management should:
- Prohibit employees from performing any maintenance work on equipment while it is in service o Barricade the swing radius of the crane structure to prevent employees from being trapped and crushed be tween rotating portions of the crane and adjacent structures o Prohibit oilers, helpers, or other workers from areas within the swing radius of the crane carriage while the crane is rotating or under load o See that oilers, helpers, or other workers are not under any portion of the crane body while a load is suspended.
(3) Rigging the Load
The proper selection and integrity of rigging material and the methods used to attach the load to the hoist are vital to safe hoisting operations .
(a) The load should be rigged so that the load is stable in the saddle of the hook.
(b) The worker should know the safe load limits of rigging equipment, which must not be exceeded. The employer can accomplish this by permanently attaching tags to, or painting a section on, each sling, rope, and chain that identifies its capacity.
(c) The employer should train all riggers in the safe operating procedures of rigging, including:
- Keeping hands away from pinch points as the slack is being taken up o Examining all hardware, equipment, tackle, and slings before use and destroying defective compo nents o Making sure that all slings are of the same capaci ty and length when two or more slings are used on a load o Making sure that the hoist rope or chain is never wrapped around the load or completely wrapped around a hook o Attaching the load to the hook by slings or other rigging devices that are adequate for the load being lifted o Securing the unused legs of a multileg sling before lifting loads with one leg o Remembering when a bundled load is picked up that the material will tend to "nest" and create pinch points, and when a load is landed, it will tend to roll or spread out o Making sure wood blocks or short lengths of steel are not carried loosely on tops of loads o Making sure wire rope or chain is never allowed to lie on the ground for any length of time or on damp or wet surfaces, rusty steel, or near corrosive substances o Avoiding draping rope slings from beneath loads o Keeping all rope or chain clear of flame cutting and electric welding operations o Making sure shackles are not rigged with the run ning rope against the pin, causing it to "spin out" and drop the load o Ensuring proper load/shackle alignment by using spacers such as washers o Keeping the load under control with guide ropes or tag lines. (e) Slings, ropes, or chains should not be left on the floor or ground where they can be subjected to abrasion or create a tripping hazard. They should be hung from a rack and looped so that they do not touch the floor.
(f) All hooks should have safety latches.
(g) Sharp bends, pinching, and crushing of ropes and slings must be avoided. Sharp edges or corners of heavy loads should be padded as protection for slings by the use of large-diameter split pipe sections, corner saddles, or other, softer material. The load should not be "picked" until the signal is received from the signalman. All signals must be clearly understood by the operator.
If there is any doubt, the operator should stop operations until the signal has been clarified. The crane operator should receive signals from only one person; this does not exclude relay signaling or emergency stop signals.
Signalmen may be supplied with orange gloves for maximum signal visibility.
(b) Crane/hoist operators should remain at the controls whenever a load is suspended.
(c) When preparing for new and near-capacity picks, the operator should make a practice run, going through all the motions without the load, anticipating the actions that should be taken to make a safe lift and a smooth operation.
(d) The crane should never be loaded beyond its rated capacity.
(e) Handling loads during high winds should be avoided.

# b. Straddle Carriers
(1) Straddle carrier operators must be thoroughly trained.
(2) Straddle carriers must be thoroughly inspected before beginning operation each day. Particular attention should be given to brakes and hydraulic systems. Visual inspections of the bridge, rigging, and lifting hardware should be made to ensure their integrity. All wire ropes should be inspected and special safety devices should be in working order.
The inspection should be performed and documented by qualified maintenance personnel.
(3) The rated load of the straddle crane should be posted in a conspicuous location on the equipment and in the operator's cab.
(4) When operator visibility is restricted, a signalman must be provided.
(5) Visible and audible alarms should be in operation during any moving task.
(6) No one should ride on the carrier unless such a procedure is approved by the plant manager.
Where approval is granted, a seat or cage, located so that it will not interfere with operator vision or in itself be a hazard, should be provided.
The rider should be in the seat or cage before the carrier is moved and should not move around on the carrier until it is stopped.

# c. Forklifts
(1) Only workers authorized by the employer and trained in the safe operation of industrial trucks, forklifts, or industrial tow tractors should be permitted to operate these types of vehicles.
(2) Forklifts and industrial vehicles should be equipped with audible backup alarms. (4) Employees should not be permitted to place any part of their bodies outside the cab or protected area of an industrial truck or between mast uprights or other parts of a truck where shearing or crushing hazards exist.
(5) Passengers are not permitted on industrial vehicles.
(6) Employees should not be allowed to stand, pass, or work under the elevated portion of any industrial vehicle, loaded or empty, unless it is effectively blocked to prevent it from falling.
(7) When loading or unloading trucks or trailers, the brakes must be set and the rear wheels chocked.
(8) Forklift forks should be carried as low as possible.
(9) Industrial vehicles should not run onto floors, platforms, or other surfaces that will not safely support the loaded vehicle.
(10) Vehicle loads must not exceed rated capacities.
A loaded industrial vehicle should not be moved until the load is secure.
(11) When leaving the vehicle, the worker should shut off the engine, set the brakes, and lower the lifting forks to the ground.
(12) All traffic regulations should be observed including plant speed limits. The operator of an industrial vehicle is required to slow down and sound the horn at cross aisles and other locations where vision is obstructed.
(13) No person should operate or be in physical control of a motorized vehicle or piece of equipment if he is under the influence of or is using alcohol or drugs.

# d. Chain Hoists
(1) Chain hoists or "come-a-longs" should be inspected and maintained as part of a preventative maintenance program. Inspection should include:
- Checking the integrity of the chain or wire rope for worn links, deformations, kinks, rust, or excessive stretch o Examining the hook for deformity, cracks, or bending o Ensuring that the clutch and brakes are within the manu facturers' tolerances.
(2) Employees lifting material with mechanical hoists should:
- Use proper and accepted rigging methods o Use safety latch hooks o Chock or block loads before working under them o Not use "cheaters" on the hoist handles. The handle length is matched to the safe lifting capacity of the hoist, and while the cheater extension may temporarily enable a greater load to be lifted, it may tax the hoist and lead to failure.

# e. Conveyors
(1) Conveyors should be adequately guarded to prevent workers from being caught on moving parts or being injured by falling materials.
(2) Conveyors should have delay startup warning devices with controls for emergency stops. All chain drives, gears, nip or shear points, and revolving shafts should be guarded.
(3) Personnel working near conveyors should wear close-fitting clothing that cannot be caught in moving parts.
(4) Employees should be instructed in safe practices for freeing "jammed" conveyors, including use of special tools. A lockout system should be mandatory.
(5) Chutes or other devices that depend on gravity for moving materials should be guarded. (2) Front-end loaders should be equipped with a backup warning device.
The device should be audible and sufficiently distinct to be heard under the prevailing conditions. The device should operate automatically upon commencement of backward motion and should operate during the entire backing operation .
(3) Loader operators should be sure other workers are in the clear before starting or moving the machine .
(A) Operators should not move loads over the heads of other workmen or over truck cabs .
(5) The loader bucket should be carried as low as possible and tilted back. This provides better operator visibility and minimizes machine bounce .

# Handtools a. Powered
Handtools (powered) should be used according to the following safety recommendations:
(1) Hand-held powered circular saws, chain saws, and percussion tools without a positive accessory holding means must be equipped with a constant pressure switch .
(2) Portable, power-driven circular saws must have guards above and below the base plate or shoe. The upper guard should cover the saw to the depth of the teeth, except for the minimum arc required to permit the base to be tilted for bevel cuts.
The lower guard should cover the saw to the depth of the teeth, except for the minimum arc required to allow proper retraction and contact with the work. When the tool is withdrawn from the work, the lower guard must automatically and instantly return to the covering position .
(3) Abrasive wheels and stones must have a safety guard cover ing the spindle end, nut, and flange projections. The safety guard should be mounted to maintain proper alignment with the wheel; the strength of the fastenings should exceed the strength of the guard .
(a) Prior to use, abrasive stone wheels should be inspected to ensure that: o They have not been damaged in transit or handling, which is checked by means of sounding with a ring test o Wheels fit freely on the spindle and remain free through an entire turn of the wheel, and that the free clearance between wheel and guard does not ex ceed one-fourth inch o A controlled clearance between the wheel hole and the machine spindle (or wheel sleeves or adaptors) is sufficient to prevent excessive pressure from mount ing and spindle expansion o All contact surfaces of wheels, blotters, and flang es are flat and free of foreign matter' o When a bushing is used in the wheel hole, it does not exceed the width of the wheel and does not contact the flanges.
(b) The safe operating speeds of abrasive grinding stones should not be exceeded .
(4) Hand-held powered drills; tappers; fastener drivers; hori zontal, vertical, and angle grinders; disk and belt sanders; reciprocating, saber, scroll, and jig saws; and similar tools must be equipped with constant pressure switches.
Other handheld powered tools, such as platen sanders; grinders; disk sanders; routers; planers; and saber, scroll, and jig saws, should be equipped with either a positive on-off control or a constant pressure switch .

# b. Unpowered
The following safe practices should be observed when unpowered handtools are being used :
(1) Train employees to select the correct tool for the job, and ensure that the tools are available.
(2) Keep all hand tools in a safe condition. Handles of tools shall be kept tight in the tool. Wooden handles shall be free of splinters or cracks.
Wedges, chisels, and other struck tools should be dressed as soon as the struck surfaces begin to mushroom.
Discard wrenches which are sprung to the extent that slippage occurs. The crowbar should have a point or toe that will grip the object to be moved, and a heel to act as a pivot point. Sometimes it is necessary to use a block of wood under the heel to prevent the crowbar from slipping and injuring the hand. Workers should position themselves so that their bodies will not be in the path of travel if the prybar slips.
Additionally, they should brace/position themselves so that they will not fall if the prying forces are released suddenly. Guardrails may be necessary to prevent workers from falling to lower levels.
(d) Employees should be aware that when using torsion tools such as wrenches, there is always a possibility that the tool may slip. Therefore, the employee should be in a braced position to maintain bodily balance should the tool slip.
Wrenches should be inspected for flaws. Wrenches should never be ground to change their dimensions to make them fit in close quarters. A wrench of proper size for the job must be selected.

# Worker Proximity to Operations a. Walking Through Work Areas
Work areas should be kept free of litter, trash, gravel, excess concrete spills, welding rod stubs and other junk.
All scrap, salvageable material, unused forming or reinforcing materials and equipment should be removed.
Protruding nails in wood forming material should either be removed or benl: over. Aisles around work areas should be kept clear of such items as reinforcement, welding hoses or leads, lumber, power cords, and concrete working tools.

# b. Working Near Operations
Of particular interest in this category is the need to protect workers in the vicinity of welding operations from flash burns. Whenever possible, resistance welding operations should be isolated to protect workers in the vicinity of the welding operations from exposure to the direct or reflected light rays.
This can be accomplished either by use of booths for regular welding production operations or by portable welding screens for welding being performed intermittently throughout the plant .

# Welding, Cutting, Burning
Welding, cutting, and burning necessary for making precast concrete products should be done in accordance with the following safe work practices: a. Workers performing welding and cutting tasks should be trained. c. Welding and cutting should be done in an area having a nonflam mable floor, such as concrete, but not on the concrete floor, because of the possibility of explosive spalling of the concrete.
The material to be cut should be raised above the concrete or the concrete shielded from the flame.
If welding must be done over wooden floors, a noncombustible covering material should be placed over the floor to provide fire protection and to prevent spatter from dripping through openings in the floor. The use of wet sand or metal coverings, however, may create electric shock hazards that otherwise would not exist. o Persons involved in grinding, chipping, wire brushing, and/or scraping should wear goggles or safety glasses with side shields under a face shield, o Since the chipping/cleaning tasks which utilize power tools can cause particles to be airborne for considerable distance (10 -30 feet), the operations should be isolated from other workers. If this is not practical, then workers in the vicinity of these op erations should also wear adequate eye and face protection.

# B. Safe Work Practices for Precasting Processes
Safe work practices for procedures used in the manufacture of precast concrete products are presented in this section.
Included are safety recom mendations that address the hazards of processes used in the precasting industry as well as the application of tools or equipment used in a specific process.

# Form Work a. Forms and Forming
(1) Forms and beds for casting should be: o Arranged or laid out to provide a working space, aisle way, or working platform clear of obstructions and suffi ciently wide to provide ample room for the safe movement of materials and vehicles o Provided with access steps or ramps at convenient inter vals along the bed or form o Equipped with standard guardrails, if over 4 feet high.
(2) Forms should be structurally sound so that they do not present a hazard to employees as they are built, repaired, cleaned, modified, or moved.
(3) During form assembly, components should be chocked and/or braced to prevent displacement.
(4) Safe access during vertical pipe form assembly should be provided for workers during assembly, aligning of hoisted parts, and attaching of hoist hooks.
(5) The floor, yard, platform, or other surface on which a form is placed, built, or erected should be free of litter, debris, and other loose materials that can cause tripping hazards. Also, these surfaces should be well drained and free of potholes, cracks, unevenness, or standing water that may contribute to slips and falls.. (6) Tilt tables should be capable of supporting the temporary loads of employees during forming operations in addition to the imposed load of product. They should also be chocked when in the upright position for cleaning, product removal, or maintenance to avoid collapse.

# b. Form Stripping
(1) Employees should be instructed that form bulkheads, etc., may temporarily adhere to the concrete product. The bulkheads may release suddenly.
Workers (and their body parts) should not be positioned where they may be caught between either the bulkhead, the product, and/or the form.
(2) During form stripping and product removal tasks, it is important that form bulkheads and components be cribbed, braced, or suspended by hoist to prevent their falling unexpectedly.
(3) Prying tasks should only be performed with the proper tool (crowbar or prybar). Shovels should not be used as substi tute s.
(4) Cranes or hoists should not be used to remove products lodged or stuck to the forms. The crane's safe lifting capacity should not be exceeded.
Use of properly adjusted crane load indicating devices will help avoid exceeding crane capacities.
(5) As forms are stripped, all excess material, wood, nails, and bits of wire should be removed so that the area is clean and safe. After forms are stripped, all nails should be bent or pulled immediately.

# Reinforcing a. Reinforcing Materials/Assemblies
(1) Reinforcing assemblies should be fabricated with a working level jig to avoid constant bending over to tie or weld.
(2) In the handling of reinforcing steel and fabricated assemblies, the following precautions should be taken: o Employees must be instructed and required to use correct lifting techniques, o Finished cages for pipes, columns, and beams should be moved to their final locations in the forms with consider ation of their weight and the physical capabilities of the employees assigned, o Mechanical lift assistance should be provided to safely lift pieces too bulky or heavy to be handled manually, o Bundles of reinforcing steel moved by crane or other means should be securely tied and wedged together to prevent slipping. o Rebar bundles lifted by hoist should be rigged by 2-point suspension chokers and moved in a balanced horizontal posi tion. They should not be moved in the vertical plane, o When bars carried by hand are long, bulky, or heavy, more than one worker should be utilized, o Rebar materials used in cutting and bending operations should be located such as to minimize or eliminate the need for the worker to lift the bar from ground level to the cutting or bending height, o Gloves should be worn during strand stringing, vise plac ing, rebar tying or handling, mesh placement, and cage handling tasks .

# b. Metalworking Equipment
Metalworking equipment should meet the following requirements:
- Cage rollers should be equipped with deadman switches and positive braking mechanisms that immediately stop the move ment of the rollers, o Cage or wire rollers should be equipped with trip wire mechanisms at the in-rolling nip points, that automati cally shut down the rollers when inadvertent contact is made. o Shearing machines should be equipped with physical guards and/or proximity detectors. (b) Welding or cutting should not be allowed in any stressing bed where strand has been strung or tensioned, or in any other location where strand is stored. If an electric arc jumps to or from the strand, the molecular structure of the strand is altered and a loss of strength occurs.

# c. Stressing
Heat from molten metal or torch cutting will also change the mechanical properties of steel wire strand.
(c) Strand vises used to secure strand at the anchor abut ments should be placed away from a burned end to avoid the area of altered strand strength. This distance should be at least 12 diameters of the strand or 6 inches, whichever is greater.
(d) Strand previously gripped by vises, and therefore nicked, must not be reused.
Strand vises should be cleaned and inspected between each use and lubricated as necessary. Grips that become visibly worn or distorted, or allow excessive slippage should be discarded.
(e) Check that the strands in the form are not crossed or tangled before tensioning.
(f) Audible and visible alarm signals should be turned on and remain on during tensioning. Any personnel not directly involved in stressing operations should be cleared from the "designated area" and remain clear until audible and visual signals are turned off.
(g) The "designated area" should be the entire length of the bed being stressed, including both ends and the sides out to the center line of any adjacent bed, or one-half the length of the longest member, but not less than 20 feet.
(h) Only stressing crew personnel directly involved in tensioning are to be permitted in the vicinity of the bed.
(i) Personnel in the stressing crew must not stand behind the jack or in line with the tensioned steel, since ruptured strand tends to retract along the line of tension.
(j) No employees should be in the jacking area (the area within the possible swing radius of the stressing jacks) during stressing.
(k) Elongation should be measured by means of a template, jig, or scale attached to the stressing jack that can be viewed from a safe distance.
(1) Workers involved in tensioning should be protected by bed end protection, a pumphouse, or a portable booth to shield them from flying strands or bulkheads resulting from strand breakage.
(m) An employee should be posted in a location with an unobstructed view of the designated area in order to warn personnel who inadvertently approach the re stricted area. Shields must be designed to withstand the forces applied against them by recoiling strand, flying bulkheads, and other material that may be launched as a result of strand failures during stressing.
Shields can be fabricated of sheet steel; heavy duty, small aperture expanded metal; or concrete with a supporting frame of angle iron, channel, or pipe. The purpose of bed end protection is to shield those workers who are involved in the tensioning or detensioning operation from flying chucks, strand, or bulkheads resulting from chuck or strand breakage.
The following recommendations describe possible methods of bed end protection.
Staff engineers should develop measures which are specific to the protection needs in each plant . The secondary barrier should be constructed of concrete, steel, or other material able to withstand the force of a chuck and strand retracting through the pulling head.
Alternatively., an angled trough that is of sufficient strength and dimension to collect a retracting strand and direct it toward the ground should be permanently installed at the pulling head. on the harping dowel large enough to be visible from a safe location during the harping sequence.
During harping the following safety recommendations should be followed: o All unnecessary employees should be cleared from the immediate area, o Audible and visible alarms should alert personnel that harping operations are taking place, o An employee should be stationed in a safe area to en sure that personnel do not enter the "designated area" while harping operations are in progress, o A mirror can be set up on the form so that an employee can observe the depressing clip from a safe location, o Entangled or misaligned strand should be restored to its original position and then correctly harped. Work ers must not attempt to shift strand while it is de pressed .
There are different types of harping operations, and each type requires special precautions. More detailed procedures and safe work practices are contained in the Prestressed Adapted from PCI Safety and Loss Prevention Manual .

# Concrete
Institute publication, "PCI Safety and Loss Prevention Manual" .
(4) Dejacking Dejacking, used to release a strand that is misplaced or fouled, requires extreme care.
The following precautions should be taken: o Hands and fingers must not be placed between the chuck face and the jackhead. o Jaws should be removed with a hook tool or other device recommended by the manufacturer, o Tension on strand should be released slowly. o Prior to stressing, place a solid steel cylinder, called a spacer (approximately 2 inches long and slotted to fit the strand), between the chuck and the jackhead and tape it to the chuck, o After casting and curing, remove the tape; place a "detensioning stand" over the strand; and stress the strand slowly until the spacer falls out. o Use long-handled pliers or tongs to insert a removal tool in its place; remove the chuck cap, and slowly release tension until the removal tool has forced the jaws from the barrel. When the jaws are access ible, pull them free of the retaining ring, remove them from the strand, and release tension slowly, o Keep hands out of the "detensioning stand" by using long-handled tools, o Allow no employees other than the detensioning crew in the "designated area." o Do not regrip the strand on or near the previous jaw marks. o Use warning lights and horns and enforce "designated area" precautions as when tensioning.

# Oiling
a. Supplied air pressure vessels, used for spraying form release agents, should have both a visible pressure gauge and a pressure relief valve in proper operating order. Supplied air sprayers should be labeled for their maximum safe operating pressure and this pressure should not be exceeded.
b. Form release agents should be stored neatly in cabinets or areas specially set aside for that purpose. Aisles should be maintained to allow unobstructed movement of personnel and equipment, and to avoid tripping and slipping hazards. c. Material Safety Data Sheets for all form release agents should be requested, and all applicable safety and health precautions should be followed.
d. Eye and face protection, such as a face shield, should be manda tory during spray application of form release agents.
e. A minimum of safety glasses should be used during hand applica tions (swabbing, rolling) and during all transfers of form release agents. (2) Employees should be adequately instructed in preventive measures to avoid skin burns that can occur from prolonged, direct contact between skin surfaces and fresh (moist) concrete or clothing saturated by it.
(3) Where cement, sand or gravel are stored in silos, bins or hoppers, the following procedures should be followed:
(a) Workers should be made aware that fine materials such as cement, sand and gravel can freeze or bond and crust over in cold or wet conditions. This crust can collapse under the weight of an employee standing or walking on it to free it up.
The individual could sink into the quicksand-like material and suffocate. Further information on working safely in confined spaces is contained in the NIOSH criteria document "Working in Confined Spaces" .
(4) NIOSH/MSHA-approved respirators should be worn in areas where dust levels are excessive. The threshold limit value (TLV) for specific dusts and exposure levels are cited in the 1981 TLV booklet of the American Conference of Governmental Industrial Hygienists (ACGIH) .
(5) In high-noise areas, the following; recommendations should be adhered to :
- A continuously effective hearing conservation program, in cluding annual audiometric testing of exposed employees, must be established when noise levels are found to exceed 85 dB(A) for an 8-hour time-weighted average (TWA), o Administrative or engineering controls, including rotation of exposed employees and acoustical booth isolation where feasible, should be applied to reduce exposure time, o All employees must be provided with hearing protection de vices if feasible engineering controls are inadequate in reducing noise to levels below 85 dB(A) for an 8-hour TWA.

# b. Concrete Transport
(1) A signalman should be available at times of entry, movement, and exit to ensure safe passage of concrete delivery trucks to casting areas.
(2) Backing lanes should be free of equipment, material, and workers .
(3) Movement of personnel and job equipment should be routed to avoid crossing truck lanes, tracks, aisleways, or transfer areas.
(4) Concrete delivery transporters should be equipped with audible and visible alarms, including backup alarms to warn of their approach, and mirrors to eliminate blindspots.

# Casting Concrete a. General
During the casting of concrete product, the following safety recommendations should be followed:
(1) Concrete buckets should not be transported over workers . Workers should not step under overhead buckets.
(2) Buckets should have a positive locking gate .
(3) Concrete buckets should be equipped with a release latch (bar, handle) designed and located to prevent fingers from being caught between the latch bar and the bucket.
(4) Electric cords must meet OSHA standards and be free of breaks and in safe condition. The cords should be placed or protected so that they will not be run over and damaged or be allowed to rest in water.
(5) Safe access to the points of concrete placement and consol idation should be provided by stairs, ramps, or ladders. Also, a properly guarded walking and working surface must be available. ( 6) Safe work platforms should be provided for elevated casting operations such as vertical wet casting of pipe. (7) Rolling stair scaffolds must be equipped with adequate guardrails on all exposed sides, particularly the ends of the scaffold and the interface between the form and the scaffold if a floor or wall opening exists. ( 8 o Ensuring that broken or missing handholds and footholds are repaired or replaced  o Removing and refitting unsuitable handholds and footholds  o Adding new handholds and footholds where they are needed for worker access  o Providing non-skid surfaces on all access systems which might become slippery  o Providing a handhold, long enough to be accessible by the majority of drivers, on the right of the tractor driver's door o Providing portable access stairs for pickup and trailer beds. f. Concrete products should be unloaded in accordance with the following safety recommendations:
- The safe lifting capacity of the equipment should not be exceeded. o Loads that are long, oddly shaped, or difficult to rig should be raised only a short distance until it is apparent they will not spring, slip, or tip. o Pipe or circular products should be off-loaded with skids, ropes, or automatic unloaders, o The job site unloading area should be examined for access, stability, and temporary storage capability, o Before unattended vehicles are unloaded, all wheels should be chocked and the parking brakes set. o Trailers should be loaded and unloaded evenly so as not to tip the load or the trailer.

# Personal Protective Equipment
To protect workers, the use of various personal protective equipment should become an integral part of the safety program.
The most common personal protective equipment that should be used are contained in Table IV
Requirements for personal protective equipment are covered in the OSHA standards .

# Mechanical Materials Handling
Recommendations for control of hazards encountered in mechanical materials handling activities are contained in paragraph A.2. of this chapter.

# Guarding
Guarding of machinery should conform to the following:
(a) Drives for machinery must be properly guarded at chains, belts, and pulleys in full accordance with the following requirements:
- Pulleys, belts, or chain drives 7 feet (within reach) or less from the floor should be guarded, o Gears should be guarded by a complete enclosure, o Sprocket wheels and chains should be enclosed if less than 7 feet above the floor or platform . (d) Circular, hand-fed ripsaws and crosscut table saws must be guarded by a hood that encloses the portion of the saw above the table prior to cutting and above the material being cut (the hood should automatically adjust itself to the thickness of, and remain in contact with, the material being cut) .
(e) All p< tions of the saw blade on bandsaws must be :
- Enclosed or guarded, except for the working portion of the blade between the bottom of the guide rolls and the table (bandsaw wheels should be fully encased)
- Guarded to prevent hands from contact with the in-running rolls.
(f) Radial saws should be provided with:
- A hood to protect the operator from flying splinters, broken sawteeth, and sawdust o A guard on the upper hood completely enclosing the upper por tion of the blade down to the end of the saw arbor o A lower blade guard that automatically adjusts to the thick ness of the stock and that remains in contact with the stock being cut o Nonkickback fingers or dogs located on both sides of the saw to oppose the tendency of the saw to pick up the material or throw it back toward the operator.. Further information regarding hazardous energy control is contained in the NIOSH document "Guidelines for Controlling Hazardous Energy During Maintenance and Servicing" .

# Chapter V SAFETY MANAGEMENT
There should be little disagreement that safety is ultimately the re sponsibility of management.
In addition to the fact that the Occupational Safety and Health Act of 1970 (OSHA) requires each employer to furnish each employee a place of employment that is free from recognized hazards likely to cause death or serious physical harm, worker accidents and injuries are counter-productive and costly.
As shown in Chapter III of this document (specifically Table III-3), the occupational injury and illness incidence rate for the precast concrete products industry in 1980 was in the top 3% of the durable goods manufacturing industries.
Since 1977, the estimated cost of actual paid-out medical and indemnity expenses of occupational injuries in this industry has averaged more than $30.9 million per year.
The National Safety Council estimates that the full costs of work-related accidents have been 3.4 times greater than the cost of actual paid-out claims, or over $105 million per year (see Chapter III).
These needless losses can be controlled by managing successful safety programs.
However, safety programs can only be successful when plant management provides an environment responsive to worker safety and is committed to providing a safe workplace.
Safety recommendations such as those presented in Chapter IV or safety standards such as those promulgated by OSHA will not, by themselves, reduce occupational injuries.
Management must accept the responsibility of implementing a safety program which is designed for successful accident prevention.
Such success requires an organized approach.
No individual level of management can do the job by itself.
It takes a combined effort of all -from the plant manager down through the first-line supervisor to the employees. This chapter presents the basic elements of safety program management.
It outlines criteria for evaluation of present safety programs and suggests implementation of critical elements which are indicative of safety being a management function.
It is recognized that each company will need to tailor its safety program to fit the various characteristics of its particular operation.

# A. Pre-Assessment of Present Program
Before revising an on-going safety program or attempting to design a new program, it is advisable that management assess its existing safety status within the plant. An evaluation of the present safety status will help out line where changes and additions are essential.
It will yield answers to the seriousness of the plant's accident problem, it will identify the major organizational deficiencies which have an adverse effect on the safety program, and it will identify the major accident prevention deficiencies within the program itself. Assessment of the following basic elements of the safety program should be made:
1. Management leadership 2. Assignment of responsibility 3. Identification and control of hazards 4. Employee and supervisory training 5. Accident reporting and investigation 6. Emergency plans 7. Employee awareness. Utilization of pre-assessment tools such as the American Society of Safety Engineers (ASSE) Safety Audit contained in Appendix C, or the example assessment forms contained in Appendix D can provide insight into safety program weaknesses which need management's attention. B. Basic Elements of a Safety Program It is difficult to outline a safety program that will be applicable to all precast concrete plants, since a program must vary with the specific needs of each company. It is important that a safety program be tailored for the processes and operations of an individual company. It becomes the responsibility of management to design and define a program within the constraints of a specific plant's operation. A safety program should, however, include aspects of the following basic elements:
1. Management Leadership Management's interest in safety must be sincere and visible to employees. Therefore, senior management must establish achievable safety program objectives and communicate these to all employees. The safety program objectives should receive the same management scrutiny as that given for the control of quality, cost, and production. Once the objectives are established, then management must plan, organize and control the overall program to meet the objectives. Management's leadership and support should contain the following key elements: a. Written Policy A written safety policy is management's method of communicating a direction to be followed. It is the first step in organizing to meet the stated objectives. It is important that the policy be in writing to reduce confusion concerning direction and assignment of responsibility.
The written policy should be concise, to the point, and should address the following areas: safety and health conditions . Employee participation can be encouraged by conducting safety meetings and by forming a plant safety committee. Holding safety meetings is a useful technique for communicating safety to employees. These meetings are more commonly referred to as safety huddles, tailgate sessions, or toolbox sessions. These are short

# SAFETY AND HEALTH POLICY
It is the policy of this company to provide every employee with a safe and healthful workplace. When a person enters the employ of our company, they have the right to ex pect to be provided with a proper place in which to work, as well as proper and safe machines and tools with which to do the job, and that the employee will be able to devote his or her energies to the work without undue danger. Only under these circumstances can the association between employee and em ployer be mutually profitable and harmonious. It is our desire, intention, and responsibility to provide a safe workplace, safe equipment, and proper materials and to establish and insist on safe methods and practices at all t ime s. People are our most important asset-their safety is our greatest responsibility. It is a basic responsibility for all employees of this company to make the SAFETY of fellow human beings a part of their daily, hourly concern. This responsibility must be accepted by each person who conducts the affairs of the company, regardless of the capacity in which they function. Employees are expected to know the SAFETY rules applicable to their job and must use the SAFETY equipment provided. Rules of conduct and rules of SAFETY shall be observed by all employees. SAFETY equipment must not be destroyed or abused. The joint cooperation of employees and management in the observance of this policy will provide safe working conditions and accident-free performance to our mutual advantage. We consider the SAFETY of our personnel to be of first importance, and we ask your full cooperation in making this policy effective.

# Company President FIGURE V-l. EXAMPLE OF A PLANT SAFETY AND HEALTH POLICY
Adapted from American Society for Personnel Administration, 19 Church Street, Berea, OH 44017.
As we are known and recognized for our products and service, so should we te known for our safety performance. No job must ever become so routine or so urgent that every safety precaution is not observed. Prevention of personal injury and damage to the property and equipment of both the company and its customers must always re main uppermost in the mind of every employee.
It is the policy of ABC PRECAST CONCRETE CORPORATION to develop and maintain safe and efficient operations. Our safety program has been designed, in accordance with the Williams-Steiger Occupational Safety and Health Act of 1970, to develop safe working conditions. The success of our program requires the full support of each and every employee.

# President FIGURE V-2. EXAMPLE OF A PLANT SAFETY POLICY STATEMENT
Adapted from Summary Plant Observation Report and Evaluation . meetings usually conducted by the supervisor with all his employees. The primary functions of such meetings are to foster communication between management (supervisor) and employees relating to safety consciousness,and to disseminate safety concepts. The subject should be specific to work being performed or planned for the upcoming week. The session should take place at the work site and last 10-15 minutes. Employees knowledgeable in specific safety subject areas should be requested to lead the safety discussions, thereby encouraging peer participation. Establishment of a safety committee is another technique which demonstrates management's desire that employees participate in the plant safety program. Committees may vary considerably in different organizations, but should have the basic functions of developing, promoting, and maintaining safety practices in the plant. Such committees should also serve as a means for communicating safety policies to both management and labor.

# Assignment of Responsibility
Management has the responsibility for controlling unsafe acts of employees and unsafe working conditions. Ultimately, the plant manager has the overall responsibility for meeting the plant's safety program objectives.
Since plant size and organizational structure vary widely throughout the precast concrete products industry, assignment of safety responsibilities must be appropriate for the management structure within the plant. In very small plants, the owner/operator may have sole responsibility; in larger plants, responsibility is assigned to the plant manager, middle managers and first-lin e supervisors. Additionally, the employees must also be assigned responsibilities in order to meet the stated safety program objectives.

# I d e n t if ic a ti o n and C o n tro l of H azards
Whenever management decides to either implement an accident prevention program or to overhaul an existing program, employees are inclined to be skeptical of projected results and tend to take a "wait and see" attitude. A vigorous management effort to eliminate longstanding hazards and to provide a safer workplace can convince employees that management is truly concerned about their on-the-job well being.
However, prior to eliminating these hazards, management must first identify them. Identification of hazards requires a fairly complete inspection of all precast operating areas. The inspection should be made by a small group composed of someone from production, someone from maintenance, and the safety program coordinator.
The hazard identification process should be done in phases to reduce interference with normal work routines.
Safety inspection checklists may be helpful in directing the group's inspection to the operating areas with the more hazardous work exposures. Management can either obtain checklists from insurance companies, or develop one specifically for their plant after analysis of the injury data presented in Chapter III, Table III-5. As an example, analyze nails as a source of injury. The table shows that nails mostly resulted in puncture injuries to employee's feet. Therefore, it is assumed that when wooden forms are removed from cured product, the nails are not bent over or removed, thereby creating a hazard to workers. Analysis of the "machinery" source indicates that lack of adequate guards are creating a hazard. If these sources of injury are present within the plant, the checklist should address these items. After the in itial inspection has been performed, a program for correcting the noted deficiencies and performing periodic inspections should be established. Identifying hazards by means of inspection and promptly eliminating or controlling them is one of the best methods management can use to demonstrate its interest and concern for accident prevention to employees. both new employees and employees new to a particular task. Newly hired employees should always receive instruction and orientation about the company, the plant, the product, organizational arrangements, lines of authority, and safety policies and rules. Specific training, including supervised on-the-job training, must be provided to each employee.
During orientation to the plant, a new employee should be given copies of the company's safety policy, and safety rules and regulations. If an employee starts a new task, changes tasks, or uses new or modified equipment, it is essential that quality training for this job be provided. Training may be necessary to develop a particular skill that cannot be performed safely without specific knowledge; e.g., working at a rebar bender, casting concrete, or operating a forklift. Safety training is based on the general assumption that the development of a positive mental attitude predisposes an individual to safe habits of work and conduct. A job should be explained in detail by breaking it down into manageable parts. If personal protective equipment is required, employees must understand why it must be used and what may happen if it is not used properly. Hazards should be identified, and precautions or safe work practices demonstrated. Training should take a new employee through each step, and each step should be fully demonstrated. In addition, the supervisor should verify, at regular intervals, that the original lessons are being followed and that the employee is not developing bad habits or taking dangerous shortcuts. The type of training required, by employee group, is presented in Table
V-l.
Other training, such as first-aid courses, cardiopulmonary resuscita tion (CPR), fire extinguisher use, and other emergency procedures may be required.
Training is a continuous process, and attention must be paid to all employees. An employee who continues to repeat an unsafe procedure is not working safely, even if an accident has not occurred. The following indicators might show a need for training or retraining: o High incidence of injury o An increase in the number of "near misses" that could have re sulted in accidents o A change in a process or introduction of a new process o A recent upswing in actual accident experience o Excessive waste or scrap due to poor housekeeping.

# Accident Investigation
The investigation of accidents is an important part of the safety/accident prevention program. It identifies accident causes so that similar situations can be prevented by management actions such as mechanical im provements, better supervision, or employee training. It determines the "changes" or deviation that produced an "error" resulting in an accident; it publicizes the particular hazard among employees and their supervisors; and it directs attention to accident prevention in general. Since nothing is learned from unreported accidents, even minor injuries and near misses should be investigated. The investigation of accidents is the responsibility of all levels of management. However, the firstline supervisor is perhaps the best quali fied, since he is close to the jobs, working conditions, and workers. The supervisor must be trained and have the ability to recognize the cause of accidents. This evaluation may require the assistance of management, equipment suppliers, and insurance representatives. Figure V-3 shows an example of an accident investigation form.
The basic problem confronting any supervisor interviewing a person involved in an accident is obtaining complete facts. Often a worker is reluctant to cooperate for fear of ridicule, sarcasm, or reprimand. It is important to stress the need for facts so that recurrence can be prevented in the future. It is also helpful to ask individuals involved in accidents for their ideas on making the job safer.
Witnesses are important sources of accident information. When a fatal injury occurs, a witness may be the only direct source of information available. When a serious injury occurs, a witness may be the only means of verifying incoherent pieces of the injured's account. For minor injuries, a witness may be able to clarify some of the circumstances surrounding the accident better than the injured person himself. This is also true of near accidents that have a potential for serious injury.
In all cases, all levels of management can learn how to prevent accidents through investigations. By investigating accidents, similar unsafe practices and conditions can be monitored in the future. The information compiled can also help to design better training programs, emphasize areas needing management's attention, and generally prevent future potential problems.
Management's participation is highly important to a functioning safety program in the precast concrete products industry. Efforts should be made to reduce the unnecessary costs of worker injury and illness, loss in production time, as well as repair and replacement of damaged machinery and products.

# Emergency Plans
Management should have a written plan of action outlining procedures to be taken in emergency situations such as employee injury and fire. The purpose of the plan is to eliminate as much confusion as possible in order that immediate positive response will be taken to minimize the dangers of the emergency.  firefighting equipment appropriate to the work space, materials, and expected hazards. Canada also requires that facilities for producing prestressed con crete elements include measuring equipment for setting up and checking alignments and levels. Canada requires that there be adequate dustcollecting and ventilating capabilities when personnel are in woodworking shops where wood or plastic forms are made.

# Reinforcing
Canada requires that work benches or gigs where welding is performed be arranged so that employees are protected from welding flashes and that the areas be ventilated to avoid exposure to excessive welding fumes.
PCI refers to the OSHA General Industry Standards in 29 CFR 1910.217 and requires welding areas to be ventilated and protected to prevent welding flash.

# Stressing
Both Canada and the PCI have safety requirements for stressing opera tions. The PCI requires that a shield or guard be provided for bed end protection of the jacking area. There are suggestions for the materials for a barrier, but no specific requirements.

# Oiling
There are no unique safety standards in any international or consensus standards that address the tasks of this operation, except those discussing walking and working surfaces in the PCI "Safety and Loss Pre vention Manual" .

# Mixing
The PCI has no specific safety standards regarding batching and mixing that relate to safety. The Canadian standards require that the batch plant be kept clean at all times.

# Casting
The PCI recommends that gloves, long-sleeved shirts, and long trousers be worn when employees are performing any of the various tasks related to concrete operations, such as shoveling, raking, vibrating, and screeding. The PCI requires that personnel performing the shoveling tasks be trained in proper procedures to reduce the potential for back strains. They also require that extruder hoppers have guards and that all electrical connections be insulated or guarded.
The PCI refers to requirements regarding noise in 29 CFR 1926.52 and CFR 1910.95.

# S trip p in g
There are no specific requirements in the PCI, ACPA, or Canadian standards that apply to tasks in the stripping operation.

# Curing
The PCI has both recommendations and specific requirements concerning steam, hot oil, electric, and moisture curing. They include requirements for the insulation of steam, hot: oil, and hot water lines and for thermostats, timers, and circuit breakers for electric curing.

# Finishing
The PCI "Safety and Loss Prevention Manual"  recommends the use of rubbersoled shoes where there are slippery surfaces and requires the use of hard hats, eye protection, knee pads, and gloves in the performance of certain operations; e.g., gloves are required for all finishers working with concrete; eye protection is required while concrete is poured; and eye protection is required whenever finishers are chipping, burning, drillling, or grinding. During special finishing processes such as sand blasting, the PCI re quires adequate exhaust ventilation and respiratory protective equipment. When acid etching is used as a finishing technique, the PCI requires that warning signs be posted and visible, that all caustic and acid products be labeled, and that employees know the location of the nearest portable water supply. It also recommends the use of protective face, hand, foot, and body clothing for employees performing these tasks.

# Materials
Handling PCI refers to 29 CFR 1926.600 for certain general requirements, but also specifies in its "Safety and Loss Prevention Manual"  that operators be trained and qualified, be able to pass at least a verbal examination, be specifically designated to a particular task, and make a daily minimum check of their equipment. PCI also requires that the grounds be properly maintained for safe operations and prohibits the carrying or holding of loads over work areas where other employees are present. The ACPA requires that product handling conform with the standard recommendations in its handbook.
Canada requires that all physical production facilities be laid out, designed, and constructed so that there will be adequate space for mate rials, storage, equipment, and production facilities, with sufficient capacity so that production can be adequately maintained without adversely affecting the safety of plant, personnel, or products.
The PCI has both general and specific recommendations for yard storage, including storage area, dunnage, stacking, personnel safety, strand, and rebar storage. They also have recommendations regarding product trans portation, including operating rules for driving in hazardous weather. The PCI prohibits the use of drugs and alcohol; it also requires that drivers wear hardhats and safety shoes.
The OSHA General Industry Standards in 29 CFR 1910  regulate safety and health in the precast concrete products industry (SIC 3272); however, the standards do not apply to all operations, tasks, and conditions specific to the industry. Those items in the existing standards that are related to the manufacture and delivery of precast concrete products are presented in Table B E. Summary OSHA General Industry Standards apply to many of the operations, tasks, and conditions typical of precast concrete manufacturing operations. These OSHA regulations address subjects such as walking and working surfaces, handtools, ventilation, noise, fire prevention, respiratory protection, machine guarding, ladders, scaffolding, and welding or cutting. OSHA standards do not, however, regulate some of the tasks, equipment, and opera tions that are specific to the precast concrete products industry, such as forming, stressing, detensioning, oiling, concrete transport and casting. Existing international standards and trade association guidelines address many of the hazards that are unique to tasks in the precast concrete indus try. PCI provides guidelines for worker protection in such areas as ten sioning, architectural and structural product storage, yard layout and cleanliness, product shipping, and steel placement. ACPA guidelines address the areas of pipe handling and unloading.    In addition to ef fective accident analysis, results are used to pinpoint accident causes so accident prevention objectives can be established. Written requirement that all property damage accidents of $50 & more will be investigated.  higher range (generally between 30 C and 70 C), the term "accelerated curing" is used.

# Investigation of property damage.
The process of creating draped strand.
The release of tension from the tendon, usually occurring at the time the prestressing force is transferred from the bed anchorage to the individual pieces cast in the bed.
The minimum concrete strength specified for individual concrete elements before the prestressing force may be transferred to them. A strand that is held up at specific points, and held down at others, to form a special desired profile.
Concrete designed with very low water/cement ratios and slumps to be used with special consolidation methods, tamping, or extrusion production equipment. Materials (usually wood) used for keeping concrete products from touching each other or other materials during storage and transportation.
A structure or mold for the support of concrete while it is setting and gaining sufficient strength to be selfsupporting .
A substance applied to the forms for the purpose of pre venting a bond between the form and the concrete cast in it.
The system of support for freshly placed concrete, including the mold or sheathing that contacts the concrete as well as all supporting members. The parts of a strand vise that actually contact or grip the wires or strands.
A collective term used to cover all items embedded in the concrete (other than reinforcement) or otherwise used in connecting precast elements or attaching or accommodating adjacent materials or equipment:.
A device to align parts of an assembly, usually for pre assembling reinforcing steel and hardware cages, with a minimum of measurement and consistent accuracy, from one cage to the next. A device designed to provide two or more lifting points of a precast concrete element with predictable load dis tribution and prearranged direction of pulling force during lifting. Products cast by one or more machines specifically design ed for the purpose. Slipform and extrusion machines are types of casting equipment used to make solid or hollow-core slabs. Finishes applied by special tools while the concrete is s till in the forms and plastic.
Concrete with a near-zero slump to be used with special consolidation methods, tamping, or extrusion production equipment.
A concrete element cast in a location other than its final position in service. Precast concrete may be produced at the job site, in temporary plants, or in permanent factories.
A general term for any precast product regardless of classification or application. The term includes any nonconcrete items incorporated in the element at the time of manufacture.
The platform and abutments needed to support the forms and maintain the tendons in a stressed condition during placing and curing of the concrete.
An admixture that delays the setting of concrete paste.
The smoothing or leveling off of freshly cast concrete by manual or mechanical means. A screed usually has a wooden or metal edge that is moved horizontally across the concrete, pushing excess material in front of it and filling in low places.
Equipment that, in addition to serving as forms for con crete, accommodates the pretensioned strands (or wires) and sustains the total prestressing force by suitable end bulkheads and sufficient cross-sectional strength.
The drop from the top of a slump cone to the top of the unsupported concrete after the sudden removal of the supporting slump cone. The difference in height, measured in inches or centimeters, is the slump of the concrete. A wet or soft mix slumps more than a dry or stiff mix. strand chuck A device for holding a strand under tension, or vise stripping
The process of removing a precast concrete element from the form in which it was cast.

# two-blocking
The action of the crane hook block being pulled into the crane boom head. water/cement
The weight of water relative to the weight of cement in a ratio concrete mix. Enough water must be added to the mix to provide hydration. Excess water improves workability but reduces strength.
Occupational safety and health standards that address operations in the precast concrete products industry were requested from Germany, the United Kingdom, France, the Netherlands, Belgium, Australia, Canada, and Mexico. The Canadian standards  that regulate architectural and structural operations are included for evaluation. Australia, France, and Belgium have standards for the concrete construction industry, but do not regulate manufacturing operations.
The remaining countries do not have safety standards that specifically address precast concrete operations.

# B. Trade Association Guidelines
The ACPA has published a "Concrete Pipe Handbook"  that contains some suggestions on handling, unloading, and site storage. The PCI has developed a "Safety and Loss Prevention Manual"  that includes sections on subjects such as training motivation, yard storage, tensioning equipment, stressing operations, steel placement, travelifts, chucks, and harping. These subjects are specifically related to tasks or operations in the architectural and structural sectors of the industry.

# C. Foreign Standards vs. Trade Association Guidelines
International standards and guidelines are incorporated, where appro priate, in the comprehensive safety recommendations presented in Chapter IV. A comparison of these standards and guidelines are presented topically, by operation, in the following section.

# Forming
Canada requires that, in facilities for making forms and accessories, the construction of the forms be within the tolerances required for the product. They also require that all form-making shops have exits and A tool used to spread out and smooth the concrete.
An air-powered reciprocating tool used to give a textured appearance to architectural concrete products by roughening the surface.
(a) The upward deflection that occurs in prestressed concrete elements due to the net bending resulting from stressing forces and self-weight. It specifically does not include dimensional inaccuracies. (b) A built-in upward curvature in some molds for precast concrete other than prestressed to avoid deflection under load to below a defined line of finished product. Any of various construction adhesives, consisting essen tially of powdered, calcined rock and clay materials, that form a paste with water and can be molded or poured to set as a solid mass.
A mixture of cement, sand, and aggregate with water that hardens by chemical curing into a final product similar to stone in texture, weight, and durability.
A device for attachment of precast concrete elements to each other or to a building structure.
The maintenance of humidity and temperature of freshly placed concrete during some definite period following placing, casting, or finishing to ensure satisfactory hydration of the cementitious materials and proper hardening of the concrete. When the curing temperature remains in the normal environmental range (generally between 10 C and 30 C) , the term "normal curing" is used. When the curing temperature is increased to a