Edited by Rowena Davis

Part 2:

Other Crane Hazards

The following list provides a brief summary of other principal hazards to cranes:

• A thin sheet metal cab or no cab to protect the operator in the event of a falling object or upset is a persistent hazard. The Society of Automotive Engineers (SAE) has not as yet published a standard for protective operator cabs on cranes with operators’ cabs situated on a turntable. This widespread hazard is addressed further in Part II, Section 5 of the HIFI study entitled “Inherently Safer Design Principles for Construction.”
• Latticework boom cranes present a devastating hazard from incorrect disassembly of the boom. Some 65 deaths have been attributed to this hazard? (see also Appendix B, Section 1 for a list of cases). When the unsupported boom is in a level position and someone knocks out the connecting pin on the lower side of the boom, it hinges open and collapses. This hazard deserves an alternate safer design that may include a hydraulic ram to open and close the butt section of the boom, lowering other sections of the boom to the ground as in Illustration 26.

Illustration 26: Alternate safer design for boom disassembly

• Jib boom stowage on hydraulic telescoping booms presents another prominent hazard. A jib boom stowage system that relies upon manual pin placement results in the falling object hazard of the jib boom falling free. When the heavy (approximately 2,000 lbs.) jib boom falls due to improper stowage, it may strike someone, causing serious injury or death. This hazard occurs when jib stowage is attempted with the use of a pin to anchor the jib to the side of the main hydraulic boom, as it is often misaligned with the anchor pin holes. (See Appendix B, Section 2 for a list of cases.) Correct stowage of the boom is dependent upon error-free alignment of the anchoring pin holes, which can be difficult to visually verify. Misalignment of the pin in the proper hole leaves the jib boom susceptible to falling from the intended anchor point.
  
  There are five redundant safeguards that will control and reduce this hazard:
  • Provide a separate automatic latching device to secure the jib boom when it is swung into the stowage position. This latching device needs to be a bar that allows the jib boom tip to slide into a secondary latch.
  • Provide a ramp curb rail to slide a secondary latch onto the jib boom for a forked metal guide that will ensure for a positive snap and engagement onto a vertical bar.
  • Create alignment marks clearly visible for the crane operator at the control station to confirm that the pin is properly aligned with the anchor pin holes. These alignment marks will make sure the anchor pin secures the jib boom in the secured position.
  • Design a single hinge pin that secures the jib boom onto the outer hydraulic telescoping boom in its lifting capacity so that it cannot be removed until the jib boom is locked in its stowage position.
  • The operator station should have a sturdy cab to protect against falling objects in the event that the jib boom is not properly secured and falls free.
• Self loading and unloading of load counterweights is a complex process discussed in the operator’s manual. When not followed correctly, injuries can occur. A simple approach to safely control the lifting of counterweights is to attach lifting hooks to them and use another crane for their addition or removal. (See Appendix B, Section 3 for a list of cases.)
• Track-mounted fixed boom tower cranes have two unique hazards: operator access and a need for travel alarms and other forms of pedestrian protection.
• Bridge cranes have the following inherent hazards (See Appendix B, Section 4 for a list of cases):
  • The need for a convenient lockout system
  • Unsafe access
  • Alternate control systems for multiple hoist drums to accommodate clamshell or other types of lifting
• Tower cranes have the following inherent hazards:
  • Inadequate tower footing can cause the tower to tip, requiring disassembly of the entire structure, as a tower crane cannot function as a leaning tower.
• Self-raising mobile tower crane systems are often hazardous and require following a very complicated procedure. (See Appendix B, Section 5) Self-erection cranes are currently a “cross-breed” design, which does not completely fit into the Mobile Crane standard of ANSI B30.5 or the Tower Crane standard of ANSI B30.3. This lack of distinction has caused confusion and the stifling the use of self-erecting tower cranes in California, when a tower crane collapse in San Francisco that killed five people and injured 21, following two tower crane collapses in Los Angeles in 1981& 1985, sparked statewide regulations that required a permitting process to erect a “tower crane.” In 2006 a fatal tower crane collapse occurred in Bellevue, Wash., which led to the state of Washington enacting a crane safety law early in 2007. The law called for annual inspection of cranes by third parties and the licensing of all crane operators. These regulations negate the time and cost savings that self-erecting crane technology can bring to a contractor. There are currently only approximately 400 self-erecting tower cranes in the U.S.
  
  A European manufacturer of tower cranes has adopted the United Kingdom’s 1994 “Risk Assessment Procedures” where they attempt to list everything possible that can go wrong and eliminate or minimize those risks. This is a positive step toward system safety, as the process mimics system safety concepts first developed by the Boeing aircraft company during WWII and formalized in US Military Specifications during the period of 1963- 1969.
  
  The Five Principles of Inherently Safer Design provides a transition process whereby a systems approach can be applied to construction and to the erection process for self-erecting tower cranes. What is needed is a manufacturer’s certification that the self-erection process relies upon hazard control by elimination, guarding, use of safety factors, and redundant physical design safeguards to overcome hazards. Current reliance of user adherence to warning labels or complicated written operating procedures makes no allowances for foreseeable user mistakes and leads to recurring incidents. The concept of a self-erecting tower crane is the result of creative design engineering and should include design features to ensure that the tower and boom sections unfold automatically. This design theory should not provide the opportunity for the untrained and inexperienced worker to set up or dismantle a self-erecting crane. An alternate approach to proper mobile tower crane erection involves manufacturer collaboration with trainers and users to certify crane operators with a license to erect and dismantle this piece of equipment. Such a certification program would work in conjunction with training for load moment indicators in self-erecting cranes to avoid modes of operation that lead to upset or collapse. Operators certified in tower crane assembly and use of LMIs are important parts of safer construction.
  
  With this emergence of proactive crane safety, the ball is in the court of the manufacturers, distributors, and rental agencies. These entities have the responsibility to ensure for safe design and licensing of erectors. They should act immediately and independently and not wait for future standards or legislative governmental supervision.<sup>7
  
  7</sup> For further discussion on this subject, the cover story, “Defining Self-Erectors” by Phil Bishop, Lift and Access, March 2007 gives an excellent overview of the applications of self-erectors.
  
  
• An open hook, often characterized as a “killer hook” on a crane, often lacks an effective latch and allows the strap or chain to slip out of the throat of the hook. (See Appendix B, Section 6.)
• The fall block (pulley) usually has an unguarded sheave, which provides the opportunity for anyone attempting to handle the block to have their hand caught in the nip point where the cable contacts the sheave. An obvious design improvement is to provide a handle on each side of the block.
• Two-blocking (See Appendix B, Section 7).
• Cranes create two significant pinchpoints. (See Appendix B, Section 8.)
  • The narrow clearance between the crane’s truck bed or crawler tracks creates a pinchpoint that has resulted in a number of injuries. (See illustration on page 69 of Crane Hazards and their Prevention.) Counterweights can also create a deadly pinchpoint.
  • The positioning of a crane next to a fixed object such as a tree, wall, or other vertical abstraction creates a whole-body pinchpoint between the rotating counterweight and the fixed object. (See illustration on page 68 of Crane Hazards and their Prevention.)