New York Construction Crane Disaster with Respect to Health and Safety Aspects - Essay Example

Introduction : The aim of this case study is to discuss about the incident of 15th March , 2008 , New York construction crane disaster in which seven people were killed and several injured . Initially , the case study discusses how the incident happened . It reasons out the causes for the disaster as the collapse of the multi storey construction crane . Later the case study discusses , the actual technical aspects of the construction crane and then the facts about the possible hazards of this type of lifting equipment . Later the case study discussion shifts to the aspects of the health and safety issues involved in operating such complicated equipments like multi storey constructional cranes . The statutory requirements for safe operations and the government regulations for such lifting equipments are discussed in detail in this case study , along with risk assessments before starting crane operations . The actual disaster : The incident took place on the 50th street , New York , when a 19 storey construction crane collapsed onto a building . In the disaster six construction workers and one resident woman were killed and twenty four others were injured . The disaster had such an impact that all major construction work were stopped in the New York City as quoted by 1010WINS in it’s article ‘Seventh body removed from crane collapse’ ( 1010WINS, 17th March 2008 ) . Another information from Eyewitness news says that seven buildings were damaged in the disaster and many residents had to be evacuated immediately . This has been quoted as ‘ Buildings forensic engineers have confirmed that at least 7 buildings sustained damage during the accident ’ in the article ‘ Did piece of nylon cause crane collapse ? ’ , ( Eyewitness news , 19 March , 2008 ) . The impact of the disaster is evident from fig. 1. This disaster at the site of a high rise condo residential building , has been declared as one of the worst construction accidents in the history of New York city . Fig. 1. Impact of the disaster . Cause for the disaster : Investigation of the disaster says that the cause of the disaster could be the breakage of a $ 50 piece of Nylon , says Eyewitness news , while a six ton piece of steel was being lifted . The suspected nylon webbing was found attached to the collar of the construction crane , conforming that the disaster might have been set off by this crucial part of the lifting equipment . Also it had been found that the construction tower crane had toppled when a steel collar meant to tie the crane fell down during installation . This has damaged the lower collar made of steel . This has led to lack of counter – weight , the tower crane had collapsed . The crane had broken into pieces and toppled across 51st street , buildings in between 51st and 50th street and across the 50th street . The broken crane structure could be seen in fig . 2 . Fig .2. The broken structure of the constructional crane . Construction processes with Cranes : Safety becomes the priority in any work environment. Today’s latest technological inventions pave way for more sophisticated high rise constructions within lesser time. These new methodologies ease the construction work as well as they have inherent disadvantages with respect to the safety. The construction industry has the highest ‘ rate of injuries and fatalities ’ compared to any other industry says Rivara and Alexander (Occupational Injuries .. , 1994 ) . Under such circumstances, it is necessary that careful planning , organising and detailed study should be carried out before building a construction that is supposed to have all modern amenities and conveniences . The paramount need for safety and security of human lives as well as properties has to be given the highest priority . Design Characteristics of constructional tower cranes : The two main important characteristics of constructional tower carne design are lifting capacity and stability of the crane . These depend on the weight of the load and the distance of the hoist from the centre of gravity . These cranes provide a good height and load lifting combination . Generally these cranes have a hammerhead which is fixed horizontally or a variable luffing boom which is angled with respect to the horizontal (Shapiro. L.K. & Shapiro.H.I. , 1998) . The simple parts of a constructional tower crane are the lever , pulley , hydraulic cylinder and others . To operate with high stability within less space the vertical part has to be lifted floor by floor using jacks . The boom or jib is generally fixed to a turntable , where the slewing system is situated . The counterweight can be of concrete blocks . These constructional tower cranes are operated by an engineer who either sits in the crane or uses a remote control from ground . The operation of constructional cranes requires technical skill and experience as the load capacity , maneuverability and stability of the crane vary for the different types of loads . Knowledge of these design characteristics of the construction tower crane becomes essential to understand for it’s safe operation . Dangers associated with constructional tower crane operations : There are many factors responsible for the disasters and risks at Constructional sites. A survey in Britain says that, cranes are responsible for almost 17% of fatalities at construction sites ( Health and Safety Executive , 1978 ) . The fatality occurrence is less among crane operators whereas the rate of fatality is more for the other workers involved in the construction work , says ( Pratt S.G. et al, 1997 ) . There are many hazards associated with a constructional tower crane . These are related to the basic structural design of the crane , strength and stability of the crane and other operational hazards . Some of the possible hazards while using tower cranes are as below. Stability of base : For proper stability of a construction tower crane , the sum of moment torques with respect to the base must be null – zero. Practically , the allowable rated load for a crane must be always a lesser value than the load for which the crane would start tipping . The crane would tend to fail when the stress in the base area happens to be less than the yield stress . Generally using outriggers increases the stability on solid ground . Structural design : These constructional tower cranes occupy lesser space and have good manoeuvrability . They have large beams onto which the vertical portion is mounted . The jib or boom are placed on a turntable which houses the slewing bearing and slewing machinery . While the boom suspends the weight from a trolley , the counterweight is of concrete blocks . There is a climbing section in tower cranes along their support section , this enables the crane to attain increase in elevation as the building rises high . Constructional Tower cranes have a boom which is horizontal and is mounted on a trolley or they have a movable boom which can vary in different angles . The structure of a tower crane may have heights up to and over 200 feet . Generally they can load carrying capacity varies from 0.5 tons to around 20 tons . Operational risks : These constructional cranes are generally operated by an engineer . He works in synchronism with a rigger who is responsible for rigging operations and a signalman whose responsibility is to guide the loads . The possible operational hazards could include the factors mentioned below Overload and load impact : According to David Mac Collumin ( Critical Hazard Analysis of Crane Design , 24 : 31–36 ) one of the major factor for crane failure is overloading . This overloading leads to unexpected collapse of the boom or other structural damage of the crane which could injure the workers working in that area . Unexpected heavy winds may also add up to the load , and is called as wind loading . Electrocution : Electric shock from crane parts can be dangerous to the life of the operator and workers . The major sources for electrocution can be contact of the constructional tower crane with the nearby power lines , short circuit in crane power supply unit or contact or short circuit in the cables . Assembly and dismantling : The assembling of the tower cranes is by jacking and insertion which is done at the ground level . During dismantling small cranes have to be placed on the completed building to dismantle the top portion step by step in the construction tower crane . Carelessness during these processes could be more fatal and injurious to the workers involved in the construction . Being struck down Unintentionally : Due to lack of proper communication between the operator and the signalman or operator and the rigger , there may be situations where the workers are struck down with a fully loaded crane . Some of the other hazards that are involved in operating the constructional tower crane include , boom overturn , turntable overturn , killer hooks , confusion in the control , rigging failure . The American Occupational Safety and Health Administration, OSHA says that major factors for deaths related to cranes as follows Electrocution . Crane assembling and dismantling process . Collapse of the boom . Overturn of the crane . Failure in rigging . Improper load or overloading . Accident or striking with the moving load . Wind loading . Proximity hazards due to Power lines structures, limited space for maneuverability , lesser stability of the ground , etc . Other reasons may be due to hooks and hoist . Also cranes may fail to operate and these failure modes could be outrigger failure , killer hooks , side pull , hoist limitations and others . Statutory requirements for crane operations : To ensure safe operation of the lifting equipment , there are certain statutory requirements that have to be satisfied . In a construction site , there may be many possible hazards , among them hazards due to fire accidents and operational accidents related to lifting equipment like crane and elevators can be disastrous . Thus there are many statutory requirements that are to be considered with respect to fire safety and crane operation safety . The UK government has prescribed some statutory British standard regulations with respect to fire safety , which come under the role of the Fire Precautions Act , the Workplace Regulations , Health & Safety at Work Act and the Regulatory Reform - Fire Safety , Order 2005. These regulations provide instructions regarding various steps that have to be adopted to prevent fire accidents in construction site . The government of UK has also come out with The Lifting Operations and Lifting Equipment Regulations ( LOLER , 1998 ) to regulate the statutory requirements of lifting instruments . These guidelines cover aspects like strength and stability , positioning and installation , organizing the lifting operation , etc . Some of the statutory requirements posed by the lifting regulations are as follows , Strength and stability : The lifting equipment must have sufficient strength for different types of loads and stability with respect to the mounting point . The attachments of the lifting equipment such as anchoring elements , the interchangeable elements like grab and jib , the lifting accessories such as slings and eyebolts are expected to have good strength . Lifting equipment for lifting persons : Lifting operations has to ensure the safety of the operator against risks like carrier falling, getting trapped or crushed . A safety chain or suspension rope to free a person who is trapped . Positioning and installation : The positioning and installation of the lifting equipment must be such that the risk of striking a person is less . The risk due to drifting of the lever , falling from hoist way , unintentional release of the load must be minimized by proper positioning . Organizing the lifting operation : The lifting operation linked with raising and lowering of the load must be planned properly by a competent person . The organization of the lifting process has to be supervised and it should be done safely . The above mentioned statutory requirements are to be complied by the employer for safe working of the equipment and the workers . Safe system of work for crane operations : To ensure a safe working environment in the construction site , proper inspection before and during the crane operation is essential , says National Safety Council , ( Accident Prevention Manual for Business and Industry , 1992) . The HSE ( LOLER , 1998 ) specifies regulations for the thorough examination and inspection of the lifting equipment . Thorough examination must be done for the following circumstances If the equipment is being used for the first time . Examined after the installation in a new site but before starting the service . This is to check proper installation . The equipment has to be inspected at least every six months for any deterioration . The inspection and examinations are done by a competent authority after an exceptional disaster that might have affected the crane lifting ability. Apart from these , sufficient supervision by a competent person is required during the erection , raising and dismantling of the crane . The supervisor has to certify the support provided by the soil structure for the maximum movement during overturn . Care must be taken to fit proper limit switches to limit the rotating range of 360 degrees . Another aspect for safe working is the consideration for communication between workers because lack of proper communication may lead to disasters . Also the building under construction must be inspected for it’s capability to accept the torque and loading pressure from the crane . This has to be done before installation , else it may lead to the collapse of the structure . Care has to be taken to ensure that workers are not injured by the collapse of the booms after removal of their retaining pins . Further worker should not be allowed to work under the crane boom . The inspection has to be done by a competent person who is trained and qualified . He is expected to have adequate experience . Proper record of inspections has to be maintained with particulars of date and the condition of crane equipments . The specific parts that need to be inspected are as follows The nature and properties of the material that is to be lifted . Stability for full load conditions must be inspected with a note of the Safe Working limit ( SWL) of each and every part of the lifting equipment . Protective measures in case of mains supply failure . Protection against interference due to Electro – Magnetic – Fields ( EMF ) upon the equipment . This comprehensive inspection procedure and risk assessment has to involve more than one person , because precise inspection which will lead to safe working systems . Proper precautions to prevent disasters : Safety devices : The number of fatalities and injuries due to crane operations can be reduced by proper utilization of certain safety devices . Some of these devices are detailed here . The proximity warning device can detect the existence of Electro Magnetic Fields and they provide a warning signal to the operator says Suruda . A. ( Electrocution at work , 27 – 32 , 1988) . These devices help to reduce the hazards due to electrocution and power line proximity . Electronic monitors may be connected to load pins or tension links to display the weight of the load being lifted . These devices give alarms when there is overload . To avoid collapse of the boom , electrical interlock boom stop systems may be used . These boom stops does not allow the boom to be raised after a certain angle which could lead to the contact of the lifted load and the under side of the boom . The hazards due to wind loading can be avoided by using wind sensors and pertaining to the weather forecast . The rigger protection mechanisms reduce the fatalities due to rigging failures . The crane cabs must be provide with distortion free safety glass which is resistant to impacts . Non conducting line strings with flags when fitted along the power cables can act as an anti – collision device . Safety checking : Some of the prominent safety checks for construction tower cranes include checking for all load bearing parts for good design and construction . Construction crane’s foundation has been properly barricaded to prevent from being knocked by moving objects ’. Tower cranes foundation is not installed in water or rubbish . Checking the vertical position of the crane , checking other parts like limit switches , brakes , electrical cables , etc . Maintaining a schedule of inspection by competent person for every 12 months , according to the instructions given by the manufacturer . A competent person is expected to have good operating and design knowledge about the constructional tower crane . To have a complete through inspection , it is better to have more than one person to conduct the inspection on a prescribed schedule . Securing the labourers : To prevent such causalities of the workers , the following safety measures have to be adopted Provide a proper layout plan for the crane operation . This is done by a crane manager . All workers are made known about the operating zone of the crane , so that they do not approach this areas frequently . Proper care has to be taken during the assembling and dismantling processes to avoid accidents . Suruda et al ( Crane - Related Deaths in US construction industry , Report No . D2 . , 1997 ) says that 93% of crane related deaths occur only during this assembling and dismantling stage . Another factor that needs attention is the proper care for electrical safety . Electrocution involves transmission of current from different parts of the crane , so workers must not be exposed to electrical parts of the crane . Risk assessment before crane operation : Risk assessment becomes a mandatory process in any work industry to have safe working environment . Risk assessment for a construction industry could take into consideration factors like fall protection requirements , scaffolding , crane lifting operations , etc . To ensure safety at work , the risk assessment procedure should include the following strategies Risk assessment has been done for each and every individual crane work process like installation , maintenance , dismantling , lifting operation . Safe work procedures are devised and implemented before beginning any work . All equipment have to be checked whether they are operated in their safe working limits ( SWL ) . Safety work procedure are made known to all people involved in the crane usage like rigger , crane operator , signalman , lifting supervisor and others . Proper risk assessment team has to involve personnel from all related departments like equipment supplier , equipment operator , the crane contractor and the occupants . General safety measures for constructional cranes : The stability of the tower crane can be ensured by installing the crane at proper ground level . The ground should be free of water stagnation and other rubbish. According to Richard et al ( A Review of Crane Safety in the Construction Industry , Volume 16 ( 12 ) , 2001 ) when the crane is installed in a lesser stable ground additional ‘heavy reinforcing material like timber’ should be used to ensure stability . Proper load calculation must be done while loading the crane , overloading may lead to boom collapse which would be fatal . The tower cranes must be provided with proper support systems to add strength to the existing ropes and other structures . According to David using tag lines ensure that the load does not swing into the boom . OSHA and ANSI standards have to be followed for the rope designs . Rope diameter and deformation regulations must be inspected regularly . Operational hazards need to be addressed by proper training of the operator , rigger , signalman . Using current sensing devices can help in avoiding fatality due to electrocution . Using wind sensors and electronic sensors to assess load can assist in load calculations during windy weather . Other upset devices like angle indicators , load charts , Load Moment Indicators ( LMI ) are useful in avoiding accidents . Thus proper safety precautions can lead to less accidents during the construction work with cranes . Conclusion : The above case study , discusses the about the incident of New York construction crane disaster that happened on 15th March , 2008 , in which seven people were killed and several ( twenty four ) people were injured . This disaster has been detailed in depth and the cause for the disaster had been highlighted according to the investigations done about the disaster . As the cause happened to be failure of proper operation of the construction crane , a detailed in depth study of the design and characteristics of construction cranes has been done . Later , the requirements for the safety regulations and the safe system of operations binding to the constructional crane installation and operations have also been discussed . Finally , the possible risks and hazards related to crane operations have been detailed along with the need for risk assessments . The case study has also discussed the general health and safety measures of constructional cranes . References : Did piece of nylon cause crane collapse? , Eyewitness news , 19 March , 2008 . http://abclocal.go.com/wabc/index Health and Safety Executive. One Hundred Fatal Accidents in Construction. Her Majesty’s Stationary Office: London, England (1978). ‘Seventh body removed from crane collapse’ , 1010WINS , 17th March 2008 . http://www.1010wins.com/ MacCollum, D.V.: Critical Hazard Analysis of Crane Design. Professional Safety 24:31–36 (1980). National Safety Council. Accident Prevention Manual for Business and Industry: Engineering and Technology. 10th ed. National Safety Council: U.S.A. (1992). Pratt, S.G.; Kisner, S.M.; Moore, P.H.: Machinery-Related Fatalities in the Construction Industry. Med 32:42–50 (1997). Richard L. Neitzel, Noah S. Seixas, and Kyle K. Ren, A Review of Crane Safety in the Construction Industry, Applied Occupational and Environmental Hygiene Volume 16(12): 1106–1117, 2001, Copyright Applied Industrial Hygiene 1047-322X, 2001 Rivara, F.P.; Alexander, B.H.: Occupational Injuries in Clinical, Occupational, and Environmental Medicine. Saunders, Philadelphia (1994). Shapiro, L.K.; Shapiro, H.I.: Construction Cranes. Scientific American 258:72–79 (1988). Suruda, A.: Electrocution at Work . Prof Safety 27–32, July 1988. Suruda, A.; Egger, M.; Liu, D.: Crane-Related Deaths in the U.S. Construction Industry 1984–94. The Center to Protect Workers’, Rights (Report No. D2-97) (1997). Read More