Safety Science 51 (2013) 118–126

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Safety Science

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Safety risk management for electrical transmission and distributionline construction

Alex Albert ⇑, Matthew R. HallowellDepartment of Civil, Environmental and Architectural Engineering, University of Colorado, 428 UCB, 1111 Engineering Drive, Boulder, CO 80303, USA

a r t i c l e i n f o

Article history:Received 29 September 2011Received in revised form 25 January 2012Accepted 3 June 2012Available online 21 July 2012

Keywords:Occupational safetyRisk managementInjury preventionElectrical transmission and distribution

0925-7535/$ - see front matter � 2012 Elsevier Ltd. Ahttp://dx.doi.org/10.1016/j.ssci.2012.06.011

⇑ Corresponding author. Tel.: +1 970 227 3757; faxE-mail address: alex.albert@colorado.edu (A. Alber

a b s t r a c t

Prior research has established that electrical contractors involved in the construction and maintenance ofelectrical transmission and distribution (T&D) lines are at extremely high risk of electrocution. The resultof inadvertent contact with T&D lines often is death or severe injury that involves damage to internalorgans, musculoskeletal disorders, neurological damages and severe burns. The Electrical Safety Founda-tion International has demonstrated that contact with overhead power lines has been the single largestcause of electrical fatalities over the last decade. To reduce this disproportionate injury rate, electricalcontractors implement many strategies such as the use of rubber insulating equipment, and lockingdevices. Unfortunately, these strategies are often cost-prohibitive in certain construction and mainte-nance scenarios. Therefore, electrical contractors are faced with complex decisions that involve compar-ing the cost of injury prevention with the expected safety benefit. This paper presents research thatobjectively evaluated the risk associated with common T&D construction tasks and the effectiveness ofspecific injury prevention techniques. The research team then developed a decision support frameworkthat provides electrical contractors with objective safety and cost feedback given specific project charac-teristics. The results indicate that many of the effective strategies implemented to reduce T&D electricalinjuries are very costly (e.g., de-energizing lines). Consequently, under most conditions, the costs ofinjury prevention far outweigh the cost savings associated with the reduction of injury rates. The impli-cation of these findings is that T&D electrical contractors must highly value the non-monetary benefits ofinjury prevention in order to improve safety in their sector.

� 2012 Elsevier Ltd. All rights reserved.

1. Introduction

According to the US Energy Information Administration (2010),more than 4 billion mW h of electricity is generated annually in theUnited States to serve more than 300 million people. This electric-ity is transmitted for consumption through electrical transmissionand distribution (T&D) lines. The nominal voltage in bulk transmis-sion lines can be as high as 750 kV, which can cause instant deathwhen contact is made (Short, 2004). Workers involved in the con-struction and maintenance of these electrical T&D lines are at ex-tremely high risk of electrocution. In fact, according to theElectrical Safety Foundation International (2010), contact withoverhead power lines accounted for an average of 43% of all elec-trocutions between 1992 and 2009. Other major causes of occupa-tional electrocutions included contact with wiring, transformers, orother electrical components (27%) and contact with the electricalcurrent of machines, tools, appliances, or light fixtures (17%).

Among all occupations, the Electrical Safety Foundation Inter-national (2010) found that construction contractors account for

ll rights reserved.

: +1 303 492 7317.t).

the highest rate of electrocutions. Within the construction trade,electricians accounted for about 17% of the electrocution fatalities;construction laborers accounted for 9%; and roofers, painters, car-penters, and maintenance workers incurred a total of 7%. Behindconstruction, T&D line workers have the second highest electrocu-tion rate. The Bureau of Labor Statistics (2010a) estimated thatamong the 192 recorded electrocution fatalities in 2008, 53% in-volved T&D workers who contacted overhead power lines andthe National Institute for Occupational Safety and Health (2009)documented that 80% of fatalities among linemen have occurreddue to direct contact with T&D power lines. This injury rate causedthe Bureau of Labor Statistics (2010a,b) to classify T&D line con-struction and maintenance as one of the most dangerous jobs inthe American economy. Unfortunately, a thorough literature re-vealed no significant research into the proximal causes or methodsof prevention for T&D fatalities.

The impacts of T&D electrical injuries are substantial. The resultof inadvertent contact with T&D lines is often death or severe in-jury that involves damage to internal organs, musculoskeletal dis-orders, neurological damage, and severe burns (Lee et al., 2000).Such injuries cause long-term physical and emotional distress toworkers and their families. In addition, these injuries and fatalities

A. Albert, M.R. Hallowell / Safety Science 51 (2013) 118–126 119

result in substantial economic expenses such as: higher insurancepremiums, medical cost, compensations, lost productivity, admin-istrative costs, and others (Everret and Frank, 1996; Ferret andHughes, 2007; Oxenburgh and Marlow, 1996; Tang et al., 2004).According to Waehrer et al. (2007), the construction private sectoraccounted for $11.5 billion in fatal and non-fatal injuries in theyear 2002. The electrical T&D sector contributed greatly to thesestatistics. In fact, the average cost of each electrical fatality was$4 million and the cost of each lost work time injury was$42,207. Despite the high injury and fatality rates and their severefinancial and personal impacts, the electrical T&D industry contin-ues to grow at an alarming rate.

Research in the electrical T&D sector has predicted that recenttechnological advances will force utility companies to constructnew lines, maintain existing lines, and upgrade their performance(Balducci et al., 2002). It has also been estimated that the demandfor electricity will increase by more than 1 trillion kW h from theyears 2003 to 2020 Further, studies by Chupka et al. (2008) haveshown that, the electrical utilities will have to make an investmentof $1.5–$2.0 trillion by the year 2030 to keep up with the pace indemand. These investments to enhance the T&D infrastructure willlikely increase the volume and complexity of T&D electrical linework over the next 20 years (ESFI, 2010). Electrical utilities andcontracting companies clearly need to consider injury preventionstrategies that reduce the frequency and severity of injuries andtheir associated monetary and non-monetary costs. When address-ing this issue, electrical contractors and utility companies are facedwith complex decisions involving weighing the cost of injury pre-vention against the expected safety benefit.

The purpose of this study was to objectively evaluate the costsand benefits of safety management techniques in the electricalT&D sector of the US construction industry for commonly-encoun-tered work scenarios. The associated objectives of this researchstudy were to: (1) identify common work tasks performed aroundT&D lines and safety strategies used by utility companies to pre-vent injuries; (2) quantify the safety risk associated with each worktask using a combination of opinion-based and empirical data; (3)quantify the percent risk reduced by the various injury preventionstrategies; and (4) apply a risk-based contingent liability modeldeveloped by Hallowell (2011) to analyze the cost–benefit of theinjury prevention strategies under specific work scenarios. The re-sult is a stable, valid, and reliable decision support tool that pro-vides critical safety and cost feedback that practitioners can useto make informed decisions that enhance both safety and financialperformance.

2. Literature review

To provide context for this study and better understand the un-ique features of the electrical T&D sector, the writers reviewed lit-erature on the topics of electrical T&D operation, the effect of highvoltage electrical current on the human body, safety risk quantifi-cation, and safety risk mitigation. Though a thorough review re-vealed no research that had specifically quantified safety risks inthe T&D sector or the impacts of commonly implemented injuryprevention strategies, guidance from similar studies in otherindustry sectors were used as guidance. The results of this litera-ture review are summarized briefly below.

2.1. Electricity transmission and distribution (T&D) operation

Traditionally, electricity is generated by the conversion of thestored energy in gas, oil, nuclear fuel or water position (Karady,2006). Electricity may also be generated by utilizing energy de-rived from solar, wind, geothermal, chemical processes and even

landfills (Wagner, 2007). The voltage at the point of generation isusually between 15 and 25 kV, which, unfortunately, is not idealfor transmission due to losses that may occur. In order to reducepower losses during transmission, a transformer is used to stepup the voltage in the transmission line to 230–750 kV. Subse-quently, the voltage is reduced at a substation preceding the sub-transmission lines between 69 and 169 kV, which leads to the pri-mary distribution line where the voltage is maintained between 4and 35 kV (Short, 2004). Finally the distribution transformer re-duces the voltage to 120 and 240 V, which is supplied to consum-ers through the secondary distribution lines.

2.2. Impacts of high voltage electrical current on the human body

The effect of contact of electricity with the human body ishighly random and often manifests itself in a number of ways.Electrical injuries are usually induced primarily through hazardssuch as shock, arc and blast (Cardick et al., 2005). In the case ofan electric shock, the degree of the injuries is typically a functionof the intensity of current, current flow path, the duration of con-tact with the source, and the voltage magnitude (Lee and Dougher-ty, 2003). The nervous, musculoskeletal, cardiovascular and thepulmonary system can be adversely affected due to the flow ofelectricity (Spies and Trohman, 2006). Gordon and Cartelli (2009)recently categorized electrical injuries as:

� Immediate effects on the nervous system from shock currents,including life threatening effects on the heart, breathing, andbrain;� Stimulus of the muscles from current flowing through the body,

including reflex action and being ‘‘frozen’’ to the circuit;� Burns to the body from hot conductors caused by high currents

flowing through metal conductors, does not necessarily involvea shock;� Internal tissue damage from shock currents flowing through the

body that ranges from mild cellular damage to major damage toorgans and limbs; and� External burns and other physical injury due to an arc, creating

an arc flash (thermal energy) and/or an arc blast (includingacoustic and kinetic energy).

As mentioned above, apart from complexities such as asphyxia(Shoemaker and Mack, 2009), arrhythmias, asytole, and myocardialinjury (Spies and Trohman, 2006), fatalities or injuries may resulteven when there is no electrical current flow through the body(e.g., electrical ignition fire, blast, fall) (Cardick et al., 2005).Although very little can be done to reduce the severity of electricalcontact (Soelen, 2007), much can be done to reduce workers expo-sure to electrical current and to reduce the frequency of injuriesincurred.

2.3. Safety risk quantification

Quantifying occupational safety risks for the purpose of re-source allocation is becoming increasingly popular in the academicand professional research communities. Risk is defined as, a mea-sure of the probability of occurrence of an incident and the severityof the adverse consequence that results from an exposure to a haz-ard (ANSI, 2000; Lowrance, 1976; NFPA1500, 2002; NSC, 2009).These adverse effects (such as an injury) often result in cost over-runs, schedule delays, and poor performance (Sun et al., 2008). Inthe past, researchers have undertaken diverse approaches to assesssafety risk in construction and infrastructure projects. For example,Lee and Halpin (2003) utilized fuzzy mathematical techniques andexpert inputs to assess factors influencing accident potential in thecontext of trenching operations, Gürcanli and Müngen (2009)

120 A. Albert, M.R. Hallowell / Safety Science 51 (2013) 118–126

proposed a fuzzy rule-based analysis methodology to assess safetyrisk with linguistic variables, and Sun et al. (2008) using expert rat-ings and the analytical hierarchy process (AHP) in their quantifica-tion of safety risks. Other researchers have used more formalframeworks and independent quantification of frequency, severityand exposure in their evaluation of safety risks (e.g., Baradan andUsmen, 2006; Jannadi and Almishari, 2003; Hallowell and Gamba-tese, 2009). These studies identify risk as a function of the fre-quency of incidents; severity of injury; and exposure duration.Eq. (1) shows the relationship between the components of unit riskand Eq. (2) shows the relationships among the components ofcumulative risk. Cumulative risk is also known as expected value.

UR ¼ f � s ð1Þ

where UR is unit risk measured in $ per w h; f is frequency mea-sured in injuries per w h, s is severity measured in $ per injury.

CR ¼ UR � e ¼ f � s� e ð2Þ

where CR is cumulative risk measured in $ and e is exposure dura-tion measured in w h.

In the above equation, frequency is indicative of the prospect ofmaking contact with the hazard per unit time; severity refers tothe probable outcomes (e.g., fatalities, injuries, damages and lostwork-time due to accidents); and exposure signifies the time per-iod spent in proximity to the hazard (e.g., days). This equation hasbeen used by Soelen (2007) to demonstrate the high risk profileassociated with work on power lines. Though the frequency of con-tact is low, exposure can be high and the severity of contact is veryextreme.

2.4. Safety risk management and mitigation

The US Occupational Safety and Health Administration (OSHA)hold both the employer and the employee responsible for safetyrelated issues in the work place. The employer is to provide theworkforce with a place free from any recognized hazard (Wilsonand Koehn, 2000), personal protective equipment, and training toenhance safety performance (Spellman, 1998) and employees mustcomply with the regulations set by the employer and relevant reg-ulatory bodies.

Employers have recognized that the first step in safety riskmanagement is to identify dormant and active hazards whichmay exist or may be invoked by worker behavior at the worksite(MacCollum, 2007). This is often accomplished through reviewingthe scope of projects, schedules and other relevant documentationto identify possible hazards. According to OSHA (2002, p. 11), mosthazards in the T&D industry result due to ‘‘unsafe equipment orinstallation; unsafe environment; and unsafe work practices’’. Hav-ing identified the potential hazards, risk mitigation techniques areimplemented in order to control the frequency, severity and expo-sure level of injuries. This is typically accomplished by the use ofelectrical safety equipment (e.g., PPE, barriers); and safety proce-dures and methods (e.g., grounding, de-energizing power lines)(Cardick et al., 2005). OSHA (2002) suggests measures such as insu-lating conductors by the use of glass, mica, rubber, or plastic;guarding energized parts to avoid accidental contact; groundingof conductors and equipment to avoid voltage surges; use of circuitprotection; and other safety work practices.

Although publications by regulatory bodies set the standardsand encourage the use of risk mitigating techniques, utility deci-sion makers often are drawn towards regulatory compliance,thereby minimizing safety investment to that which is only de-manded by law (Soyka and Feldman, 1998). Their resistance canbe ascribed to the assumption that expending resources on safety,compromises profit potential by increasing the cost of the project.Despite this attitude, Lancaster et al. (2003) argued that invest-

ments in injury prevention results in economic benefits. Severalother studies show similar evidence for the cost-effectiveness ofinjury prevention in certain work scenarios (e.g., Hallowell,2010a,b; Jaselskis et al., 1996; Hallowell and Gambatese, 2009; Jer-vis and Collins, 2001; Smallman and John, 2001). However, despitethe high injury rate in the electrical T&D industry, no research hasspecifically examined the relation between injuries and benefits ofexpending towards enhancing safety. The present study has beenconducted with the aim addressing this gap in knowledge.

3. Research methods

The research process involved two distinct phases, each de-signed to achieve individual but related objectives. The purposeof the first phase was to obtain contextual information regardingthe work that contractors typically perform on electrical T&D linesand the methods that they use to prevent injuries. This contextualinformation was then used in the second phase of the researchwhere an expert panel rated the relative risks of the common tasksand the risk reduced by the various injury prevention strategies.The results were finally compiled into a decision support systemusing a risk-based contingent liability model. The details of thesephases are provided below.

3.1. Phase 1: Exploratory interviews

To initiate this 2-year research effort, exploratory interviewswere conducted with leaders in the electrical T&D sector in orderto identify common T&D construction activities and injury preven-tion strategies. These data would serve as the underlying frameworkfor the subsequent phase. Semi-structured interviews were selectedfor this initial effort because, in comparison to surveys, they providemore flexibility for exploration and deeper understanding of thesubject (Fowler and Mangione, 1990). Interviews, as opposed toquestionnaires, also allow for clarification, detailed insight, and havebeen shown to have higher response rates (Bryman, 2004).

Interviewee contacts were assembled from ELECTRI Interna-tional’s Electrical T&D Committee, member organizations of theConstruction Industry Institute (CII), and other prominent utilityand contracting company contacts held by the research team. Ofthe 17 potential interviewees contacted, four electrical contractorsand six utility representatives agreed to participate. This number ofexperts was adequate to provide theoretical saturation and re-peated evidence (Strauss and Corbin, 1998). To initiate the inter-view process, the participants were contacted via phone and thepurpose of the interviews was described. Prior to the actual inter-view date, the participants were encouraged to review projectschedules, job hazard analyses, and other relevant documents thatwould aid them in their responses. In total, 25 salient work tasksand sixteen injury prevention strategies were identified from theseinterviews. The tasks are listed and described in Table 1 and themitigation strategies are listed and described in Table 2.

3.2. Phase 2: Quantification of safety risks and risk mitigation impacts

The objectives of the second research phase were to (1) quantifythe relative risk of the common work tasks and (2) quantify theproportion of risk mitigated by typical injury prevention strategies.Because archival and empirical data do not exist for these tasks andsafety strategies, the research team decided to address these objec-tives using a detailed survey of industry experts as a primary datacollection effort based on past industry empirical performancedata. In order to obtain valid and reliable data, it was of the utmostimportance that the survey participants had a significant amountof practical experience in the electrical T&D sector.

Table 1Transmission and distribution construction/maintenance activities.

Task Brief definition

Operating equipment near energized lines Using tools and equipment to organize and stage material used for electrical facilitiesEnergize lines/equipment-put in service Placing electrical lines and equipment in service for distributing power to end usersExcavation/trenching and installing foundation Excavating and construction of the foundation to place electric facilities in position to distribute

electric power to customersClimbs pole/operates on aerial lifts Positioning workers to physically work on electric circuitsGrounding/removing grounding Using tools to bond onto existing circuits creating an electrical path to ground (creating a ‘‘short

circuit’’)Framing of temporary and permanent structures Using tools and equipment to assemble material to be used in establishing and maintaining electric

systemsInspect/troubleshooting power lines/equipment Observing present conditions of existing electrical facilitiesSplice, repair, and install conductors and wiring Using tools and equipment to effectively add onto or repair material used to conduct electricityClearing/trimming trees and bushes Using tools and equipment to remove vegetation from areas where electrical power facilities existMove energized conductor Using tools and equipment to change position of energized electric equipmentAssembling/repairing equipment and hardware The process of creating and maintaining electrical facilities.Traffic Control To aid in the flow of pedestrian and vehicle traffic for the interest of public safetyHanging and installing transformers and vaults Using tools and equipment to install transformers and transformer vaultsInstallation and connection of busses, switches, circuit breakers,

and regulatorsUsing tools and equipment to install operational components such as busses, switches, circuitbreakers, and regulators

Installing conduit or cable trough Using tools and equipment to install conduits or cable troughInstalling insulators Installing insulators to support conductors and provide insulationAssembly and erection of substation Using tools and equipment to install and erect substations to transform voltagesRemove/replace existing line Removal or replacement of electrical lines during routine maintenanceInstalling lightning arrestors Installing devices on power systems to protect insulation and other damages that can be caused by

lightningSagging to provide clearance between wires The process of adjusting the tension in overhead power linesAttaching/replacement of insulators Providing insulation after splicing conductors or regular maintenance workReplacing shield wire Replacing the shield wires during routine maintenanceInstalling/removing dampers Installing dampers to control vibrations in the cables that may be caused by windsInstall/remove spacers Using tools and equipment to install spacers to avoid contact power linesMetering/testing/measuring Using tools and equipment to monitor the performance of electric facilities

Table 2Injury prevention methods.

Injury prevention methods Description

Rubber insulating personalprotective equipment

Use of rubber insulating equipment such as rubber gloves, sleeves, line hose, blankets, covers, and mats that comply with ASTMrequirements

Using hot sticks Use of insulated hot stick poles that allow workers to manipulate and move energized lines from a safe distanceFollow safety procedures Following safety procedures as provided by regulatory bodies/electrical standards (e.g. NEC, NFPA 70E, NESC, OSHA) and general

industry safety practicesInspection of equipment prior to

workConducting detailed inspection of all electrical safety equipment prior to work to ensure its effectiveness to prevent/minimizehazards and accidents

Placement of safety grounds Connecting the circuit to the ground to prevent the building-up of line/lightning surges, static electricity, etc. when work isbeing carried out

Job hazard analysis A technique in which schedules and activities are reviewed with the purpose of identifying hazards before they occurInsulated hard hats with electrical

insulationUse of hard hats with electrical insulation which complies with the requirements of ANSI Standard Z 89

Use of Barriers and signs Use of barriers and signs to inform personnel of the existence of an active/dormant hazardSafety tags or lock-out-tag-out Use of safety tags, locks and locking devices to secure and mark lines and devices to avoid accidental energizationUse of voltage measuring

instrumentsUse of voltage measuring devises to ascertain the status of electric lines and equipment prior to be worked on

Safety grounding equipment Using of rated safety ground equipment to protect workers by short circuiting and grounding de-energized conductorsFall arrest or other restraint systems Use of systems to protect workers from the risk of falls and coming in contact with energized lines in the proximity during a fallBonding conductors to create

equipotentialMaintaining worker in an equipotential zone by connecting all metallic parts to form electrical continuity to avoid zones ofpotential difference within his reach

De-energizing T&D lines This involves the shutting down of the flow of electricity through the lines during workCradle to cradle use of rubber gloves

and sleevesUse of rubber gloves and sleeves anytime the lineman moves the bucket/boom out of the cradle when there is a possibility ofapproaching energized circuits with the bucket

Use of proper flash/thermal ratedclothing

Use of flash/thermal protective equipment when working within the flash boundary distance

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In order to be qualified as an ‘expert’ for the second phase, aparticipant must be designated as a safety professional in an orga-nization involved in the T&D industry and have a minimum of10 years of professional experience in occupational safety. Poten-tial participants were identified from the original panel in Phase1, members of the Edison Electric Institute (EII), and the NationalElectrical Contractors Association (NECA). In total, 21 experts qual-ified as ‘experts’ and agreed to participate in the study. In additionto the requisite qualifications needed to achieve expert status for

this study, eight of these individuals are Certified Safety Profes-sionals (CSP), four are certified Construction Health and SafetyTechnicians (CHST), and twelve hold advanced degrees in fields re-lated to occupational safety. Such an expert panel enhances re-search validity when obtaining a large number of samples isunrealistic (Patton, 1990). Fortunately the panel was both profes-sionally and geographically dispersed. Ten of the experts repre-sented utility companies, eleven represented electrical T&Dcontractors, and every major region of the US was represented.

Table 3Activity level risk quantification.

Task First aid Medical case Lost work time Fatality CR

F S ($) UR ($) F S ($) UR ($) F S ($) UR ($) F S ($) UR ($)

Operating equipment nearenergized lines

1.00 25.00 25.00 1.00 5,000.00 5,000.00 0.200 20,000.00 4,000.00 0.0003 900,000.00 270.00 9,295.00

Energize lines/equipment-put in service

0.40 22.50 9.00 0.20 5,000.00 1,000.00 0.189 25,000.00 4,725.00 0.0002 950,000.00 190.00 5,924.00

Excavation/trenching andInstalling foundation

0.50 25.00 12.50 0.10 2,000.00 200.00 0.100 40,000.00 4,000.00 0.0002 950,000.00 190.00 4,402.50

Climbs pole/operates onaerial lifts

1.00 25.00 25.00 0.10 2,500.00 250.00 0.100 30,000.00 3,000.00 0.0003 900,000.00 270.00 3,545.00

Grounding/removinggrounding

0.09 22.50 2.12 0.05 3,750.00 187.50 0.100 22,500.00 2,250.00 0.0001 1,000,000.00 50.00 2,489.62

Framing of temporary andpermanent structures

0.10 22.50 2.25 0.09 3,000.00 282.00 0.094 20,000.00 1,880.00 0.0002 900,000.00 180.00 2,344.25

Inspect/troubleshootingpower lines/equipment

0.10 22.50 2.21 0.10 1,750.00 175.00 0.100 20,000.00 2,000.00 0.0001 900,000.00 90.00 2,267.21

Splice, repair, and installconductors and wiring

0.50 25.00 12.50 0.14 5,000.00 710.00 0.142 5,000.00 710.00 0.0002 900,000.00 180.00 1,612.50

Clearing/trimming trees andbushes

0.10 25.00 2.50 0.10 2,000.00 200.00 0.047 17,500.00 822.50 0.0003 900,000.00 270.00 1,295.00

Move energized conductor 0.10 25.00 2.50 0.05 1,750.00 82.25 0.047 22,500.00 1,057.50 0.0001 950,000.00 95.00 1,237.25Assembling/repairing

equipment and hardware0.04 25.00 1.00 0.03 2,250.00 67.50 0.047 15,000.00 705.00 0.0001 900,000.00 90.00 863.50

Traffic control 0.02 25.00 0.50 0.10 3,750.00 375.00 0.003 20,000.00 60.00 0.0002 950,000.00 190.00 625.50Hanging and installing

transformers and vaults0.10 27.50 2.75 0.10 3,500.00 350.00 0.002 20,000.00 40.00 0.0002 950,000.00 190.00 582.75

Installation and connection ofbusses, switches, circuitbreakers, and regulators

0.40 22.50 9.00 0.14 2,000.00 284.00 0.005 20,000.00 100.00 0.0001 950,000.00 95.00 488.00

Installing conduit or cabletrough

0.55 37.50 20.63 0.09 3,500.00 315.00 0.001 20,000.00 20.00 0.0001 950,000.00 47.50 403.13

Installing insulators 0.02 25.00 0.50 0.10 2,000.00 200.00 0.001 20,000.00 20.00 0.0002 900,000.00 180.00 400.50Assembly and erection of

substation0.10 25.00 2.50 0.10 1,750.00 175.00 0.002 20,000.00 40.00 0.0001 900,000.00 90.00 307.50

Remove/replace existing line 0.05 25.00 1.18 0.02 2,750.00 55.00 0.002 20,000.00 40.00 0.0002 900,000.00 180.00 276.18Installing lightning arrestors 0.02 25.00 0.50 0.02 1,750.00 35.00 0.002 30,000.00 60.00 0.0002 900,000.00 180.00 275.50Sagging and providing for

clearance between wires0.01 25.00 0.25 0.01 2,250.00 22.50 0.002 20,000.00 40.00 0.0002 900,000.00 180.00 242.75

Attaching/replacement ofinsulators

0.02 25.00 0.50 0.01 2,250.00 22.50 0.010 12,500.00 125.00 0.0001 900,000.00 90.00 238.00

Replacing shield wire 0.05 25.00 1.25 0.03 2,500.00 75.00 0.002 20,000.00 40.00 0.0001 900,000.00 90.00 206.25Installing/removing dampers 0.02 25.00 0.50 0.02 2,500.00 50.00 0.002 20,000.00 40.00 0.0001 900,000.00 90.00 180.50Install/remove Spacers 0.02 25.00 0.50 0.02 2,500.00 50.00 0.002 20,000.00 40.00 0.0001 900,000.00 90.00 180.50Metering/testing/measuring 0.10 37.50 3.75 0.01 2,250.00 22.50 0.002 20,000.00 40.00 0.0001 900,000.00 112.50 178.75Total 5.41 140.87 2.74 10185.75 1.20 25855.00 0.004 3680.00 39861.62

F = Injuries per 200,000 w h.S = Cost per injury.UR = Cost per 200,000 w h.CR = Sum of unit risks across all severity levels for a particular task.

122 A. Albert, M.R. Hallowell / Safety Science 51 (2013) 118–126

After identifying qualified experts, the survey package wasmailed to each potential participant, which included the resultsfrom Phase 1; an explanation of the purpose, method, and implica-tions of the study; and the structured survey. As an initial step, theparticipants were asked to verify the completeness of the resultsfrom Phase 1 to ensure that all salient tasks and risk mitigationstrategies were identified. The participants were then asked tocomplete the survey, which included both risk ratings for the tasksand risk mitigation ratings for the safety strategies.

When rating the risk of each of the 25 tasks, the participantswere instructed to (1) provide an estimate of the actual frequencyof injuries that occur per 200,000 w h for each of the followingseverity levels: first aid, medical case, lost work time, and fatalityand (2) provide the typical cost in dollars for each task and severitylevel. For example, the panel was asked to provide both the fre-quency (injuries per 200,000 w h) and costs ($) of first aid, medicalcase, lost work time, and fatal injuries associated with operatingequipment near energized lines. When providing cost data, the ex-perts were asked to consider both direct costs (e.g., actual medical

expenses, material damage) and indirect costs (e.g., productivitylosses, overtime, temporary employee replacement costs). A totalof 200 ratings (25 tasks � 4 severity levels � 2 risk components)were solicited in this first section of the survey.

In the second section of the survey, the expert participants wereasked to rate the proportion of risk mitigated by each injury pre-vention strategy for each task on a 0–100% scale. For example, anexpert was asked to rate the proportion of risk mitigated by using‘hot sticks’ for each of the four severity levels. Experts were alsoasked to provide the typical costs of implementing each of the 16injury prevention strategies per worker-week. In total, 80 ratings(16 mitigation strategies � 4 severity levels + 16 costs) were solic-ited from each expert in this second section. For both sections ofthis survey, the expert participants were asked to review OSHA300 logs and company data when providing ratings. Most expertsreviewed OSHA 300 logs pertaining to the past 5 years, which isa regulatory requirement to be maintained. Two experts had accessto injury logs pertaining to the last 20 years. Also, because of thelimitation and inadequacy associated with the use of incident

Table 4Cost and risk mitigated by injury prevention methods.

Injury prevention methods Cost* ($) % Decrease in risk (rrj)

First aid Medical case Lost work time Fatality

Rubber insulating personal protective equipment 100.00 30 50 70 90Using hot sticks 75.00 45 68 85 90Follow safety procedures 25.00 80 90 90 98Inspection all equipment prior to work 25.00 50 50 50 73Placement of safety grounds 125.00 43 58 68 85Job hazard analysis 100.00 20 30 60 75Insulated hard hats - providing electrical insulation 20.00 10 20 25 35Use of barriers and signs 60.00 10 20 20 15Safety tags or lock-out-tag-out 25.00 43 63 73 85Use of voltage measuring instruments 30.00 10 50 60 78Safety grounding equipment 100.00 10 75 75 83Fall arrest or other restraint systems 100.00 10 30 60 79Bonding to the conductor to create equipotential 100.00 10 50 50 79De-energizing T&D lines 800.00 65 78 88 95Cradle to cradle use of rubber gloves and sleeves 20.00 0 50 90 90Use of proper fire rated clothing in energized areas 20.00 10 30 90 90

* Denotes cost per worker per week.

Table 5Case example showing residual risk.

Injury preventionmethods

Risk reduction – RR (residual risk – Res) Cumulativeriskmitigated ($)

% reductionin residualrisk (%)

CE UF

First aid Medical case Lost work time Fatality Total

Base-level risk $0.56 $40.74 $103.42 $14.72 0 ($159.45) – – – –Follow safety

procedures$0.45($0.11) $36.67($4.07) $93.08($10.34) $14.43($0.29) $144.63($14.82) 144.63 90.71 0.2892462 3.4572627

Rubber insulatingpersonalprotectiveequipment

$0.03($0.08) $2.04($2.04) $7.24($3.10) $0.26($0.03) $9.58($5.25) 154.20 64.57 0.0616794 16.212879

Placement of safetygrounds

$0.03($0.04) $1.18($0.86) $2.11($0.99) $0.03($0.00) $3.35($1.90) 157.55 63.81 0.0315097 31.736226

CE = Benefit to cost ratio.UF = Measure of investment required to obtain a return of $1.

A. Albert, M.R. Hallowell / Safety Science 51 (2013) 118–126 123

metrics in modeling safety performance (Cameron and Duff, 2007)in the entire industry, as presented in the OSHA 300 logs, the ex-perts heavily relied on their past experience in the industry.

4. Results and discussion

The research process resulted in a large volume of high qualitydata. In fact, 280 ratings were obtained from each of the 21 expertparticipants for a total of 5,880 ratings. As suggested by Heath andTindale (1994), Field (2005), and Mann (2003); the median ratingsrather than mean ratings were reported to minimize effects of cog-nitive biases such as recency, primacy, and contrast and to reducethe impacts of extreme outliers. The results of the risk quantifica-tion for the 25 electrical T&D construction tasks are provided in Ta-ble 3 and are sorted by total risk. The table indicates that first aidinjuries (5.41 injuries per 200,000 w h) are the most common inT&D worksites, followed by medical case injuries (2.74 per200,000 w h), lost work time (1.20 per 200,000 w h) and fatalities(0.004/200,000 w h). This is in agreement with literature that sug-gests that low severity injuries (first aid and medical case) aremore frequent in comparison to high severity incidents (lost worktime and fatalities) (Hallowell, 2010a; Hallowell, 2010b). Consider-ing dispersion in the raw data obtained from the experts (notshown in Table 3) for injuries attributable to the various tasks, firstaid injuries ranged between 0 and 6 inj./200,000 w h; medicalcases ranged between 0.001 and 4 inj./200,000 w h; lost work time

cases ranged between 0 and 3inj./200,000 w h; and fatalities ran-ged between 0 and 0.005inj./200,000 w h. The dispersion in theraw dataset for severity levels, ranged between $15 and $100 forfirst aid cases; $1000 to $20,000 for medical cases; $ 1500 to$250,000 for lost work time; and $250,000 to $1,250,000 for fatal-ities. Although there is relatively high dispersion within the data-set, most of these were due to outliers from a few surveys.

Once the unit risk of the activities are computed by multiplyingthe frequency by the cost for each severity level, one can see thatthe activity with the highest risk is operating equipment near ener-gized power lines ($9,295.00 per 200,000 w h). This is not surpris-ing, as other studies have shown the significance of consideringsafety while working with equipment in the vicinity of power lines(e.g., Hinze and Bren, 1996; Homce et al., 2001; Still et al., 1997).According to Hinze and Bren (1996), about 60% of accidents occurwhen equipment comes in contact with power lines. Other highrisk tasks include energizing lines and equipment prior to service($5,924.00 per 200,000 w h); excavation/trenching and installingfoundations ($4,402.50 per 200,000 w h); and climbing poles andoperating on aerial lifts ($3,545.00 per 200,000 w h). On the otherhand, activities such as metering, testing or measuring the voltageand current ($178.75 per 200,000 w h) and installing or removingspacers and dampers ($180.50 per 200,000 w h) are relativelylow risk.

The data from the second part of the expert survey provides in-sight to the most effective injury prevention strategies for electri-cal T&D line construction. Table 4 provides the complete results

124 A. Albert, M.R. Hallowell / Safety Science 51 (2013) 118–126

from the second survey step including the risk mitigated for eachseverity level for each task and the cost of implementation. Whenthe percent decrease in safety risk is considered for a typical pro-ject involving all the activities (i.e., a project with total risk asshown in Table 3), the most effective strategies are: followingsafety procedures and regulations set by regulatory bodies (NEC,NFPA, NESC, OSHA) (91%), De-energizing T&D lines (86%) and theuse of hot sticks (81%). The most costly strategies are de-energizingthe lines prior to work ($800 per worker per week) and placementof grounds ($125 per worker per week). The least expensive strat-egies are the cradle to cradle use of rubber insulated material andfire resistant clothing ($20 per worker per week). The writers havenot provided a computation for the cost-effectiveness of thesestrategies because these values depend on the tasks being per-formed as will be discussed in the analysis section. Consideringthe dispersion in the raw dataset obtained from the expert partic-ipants (not shown in Table 4), there was a large dispersion in thecost of de-energizing T&D lines (r = $566). This may largely bedue to the high uncertainty in determining the effect of an outageon customers. Other costs were relatively less dispersed with thestandard deviation falling between $203 for safety proceduresand $10 for the use of insulated hard hats. The standard deviationfor all strategies’ percent decrease in risk is below 29%.

5. Data analysis and application

The data collected in this study can be incorporated into a risk-based contingent liability model developed by Hallowell (2011),which allows a user to: (1) identify the most effective injury pre-vention strategies given specific work scenarios (i.e., the selectionof appropriate tasks for a project); (2) quantify the original riskof the work environment; (3) quantify the benefit derived fromimplementing selected injury prevention strategies (i.e., amountof risk reduced); (4) quantify the cost of the selected strategies;and (5) compute the cost–benefit of the collective program. Suchanalyses are critical to the cost-effective implementation of safetystrategies in the high risk electrical T&D line construction environ-ment. With the data presented in this paper, the only required userinputs are the total number of worker-hours expected for each taskbased on the schedule and a selection of appropriate safety strate-gies based on the initial feedback of the model. The computationalmodel and the integration of the aforementioned data are dis-cussed in detail below.

5.1. Step 1: Calculate base level risk demand

The first step in the decision analysis procedure involves thecalculation of the base-level risk (i.e., the condition that would ex-ist without additional safety strategies). In order to compute thisvalue for a project, the expected tasks must be identified and theirapproximate durations must be recorded. These durations repre-sent the exposure durations in the risk computations. Once thetask durations have been recorded, the cumulative risk (i.e., ex-pected value) for each task can be computed using Eq. (2) andthe total risk for the project can be computed by the summationof the cumulative risk for each of the 25 tasks using Eq. (3). As areminder, these are the values one could expect without the selec-tion of additional safety strategies.

TR ¼X25

i

CRi ð3Þ

where TR is total risk measured in $ and CRi represents the cumu-lative risk for each of the 25 tasks measured in $ and computedusing Eq. (2).

5.2. Step 2: Select injury prevention methods to be implemented

Following the entry of task durations, the cost–benefit of theavailable injury prevention strategies can be quantified and themost cost-effective strategies can be selected. To compute thecost-effectiveness values for each available strategy, the reductionin risk must be computed and divided by the cost of the strategyfrom Table 4. The risk reduction can be computed by simply addingthe cumulative risk of all the selected activities associated witheach severity level (e.g., first aid) and multiplying with the associ-ated risk mitigated from Table 4 using Eq. (4).The cost effectivenesscan then be computed using Eq. (5) which is the ratio between therisk mitigated and cost of the strategy. The user should select thestrategy with the highest cost-effectiveness rating, CEj

RRj ¼X4

m

CRm �X

rrj

� �ð4Þ

where RRj is the risk reduction for strategy j measured in $, CRm isthe cumulative risk for all selected activities combined for severitylevel m and rr is the percent risk reduction for strategy j.

CEj ¼ RRj=Ij ð5Þ

where CEj is the cost–benefit of safety strategy j measured as a unit-less ratio (obtained from Eq. (4)) and Ij is the cost of safety strategy j.

5.3. Step 3: Calculate the total investment required to support selectedsafety program and residual risk

Once the safety strategies that will comprise the safety programhave been selected, the total cost of the safety program (TC) can besimply calculated by summing the costs of the selected strategies,Ij as shown in Eq. (6). The residual risk (Res1) on implementing aspecific strategy can be computed by an iterative process usingEq. (7).

TC ¼X16

j

Ij ð6Þ

Res1 ¼ Resn�1 �X16

j

RRj ð7Þ

where Re1 is the residual risk after applying strategy j and Resn�1 isthe residual risk before applying strategy j (Resn�1 = TR at base levelrisk).

5.4. Illustration through a case example

To illustrate the application and the contribution of this study, acase example is considered and provided as Table 5. The followinginput assumptions are made: (1) the project involves the erectionof a new transmission and distribution line segment, which in-cludes all the tasks in Table 3; (2) the project requires a total of fivelabors working for a period of 4 weeks, (3) each work week consistsof 40 w h, (4) the project will require a total of 800 w h. Based onthe initial feedback, following safety procedures, use of rubberinsulating personal protective equipment, and safety grounds wereselected as the injury prevention strategies.

In Table 5 the safety strategies are implemented in their se-quence of cost-effectiveness. That is, the first injury preventionmethod to be introduced is ‘following safety procedures’ followedby the other two strategies. The base level risk (in this case, CRm),as indicated, is obtained from Table 3 which is normalized for the800 w h period. For example, the base level risk for the first aidcase is obtained by multiplying the UR ($140.87/200,000 w h) by800 w h to obtain $0.45. Following this, the Risk reduction (RRj)

A. Albert, M.R. Hallowell / Safety Science 51 (2013) 118–126 125

is calculated using Eq. (5) using rrj from Table 4. For clarity, theresidual risk (Res1) calculated using Eq. (7) is also presented.Now, the percent reduction in residual risk is computed as the ratiobetween the risk reduced after the strategy is employed and theresidual risk that which existed before the implementation of thestrategy. For example, in order to compute the percent reductionin residual risk after the strategy of following safety proceduresis implemented, the ratio between the risk reduced by the strategy($144.63) and the residual risk prior to its use ($159.45) is deter-mined (90.71%).

The table shows that the implementation of following safetyprocedures’ would reduce the risk by 90.71%. Subsequently, theintroduction of the use of rubber insulating equipment and theplacing of safety grounds would further decrease the safety riskby 64.57% and 63.81%, respectively. Although the introduction ofstrategies decreases the expected value of injuries, the implemen-tation of the safety program increases the total cost of the projectbecause the cost of implementing the strategy is higher than theeconomic returns obtained. This implies that the T&D industry va-lue non-monetary benefits that are obtained through reduced in-jury rates. In this case example, the introduction of safetyprocedures provides a return of $0.29 for each dollar invested,whereas the safety program involving the three strategies returns$0.03 for every dollar.

6. Conclusion

The objective of this study was to quantify safety risk for pro-jects involving the construction and the maintenance of transmis-sion and distribution lines at the activity level and to evaluatevarious injury prevention techniques used in the industry. Inter-views and questionnaire surveys were conducted to populate thedata and to validate the study. A decision support frameworkwas developed that provides electrical contractors and utility com-panies with objective safety and cost feedback given specific pro-ject characteristics. The reader should note that the datapresented in this paper and the associated analyses only apply toelectrical T&D construction and maintenance. The data do not ap-ply to building construction workers who account for the greatestrate of electrocutions.

The analysis computed the safety risk associated with each taskand suggests that operating equipment near energized lines posethe highest risk among the activities done on or near T&D lines.Other tasks with high risk profiles include energizing line andequipment prior to placing in-service; excavation/trenching andinstalling foundations; and climbing poles and operating on aeriallifts. Among the injury prevention methods, following safety pro-cedures and regulations and de-energizing lines and equipmentprior to work were highly effective, although certain strategiesare cost-inefficient. The framework also allows the evaluation ofthe cost effectiveness of the strategies in controlling injury rates.Finally, unlike other studies (e.g., Hallowell, 2010a,b; Jaselskiset al., 1996; Hallowell and Gambatese, 2009; Lancaster et al. Jervisand Collins 2001; Smallman and John 2001) that showed consider-able economic returns, the results of this study indicate that theeconomic returns obtained in the T&D industry by the implemen-tation of injury prevention strategies is lesser in-comparison to thegeneral construction industry. This indicates that the T&D industryhas a higher cost-utility (i.e., investment into safety interventionsexceed economic returns), which values non-monetary benefits(e.g., reduced worker turnover) and aims to reduce social costs(e.g., social equity) associated with injuries.

The results of this study will allow electric utilities and contrac-tors to evaluate risk levels associated with various projects basedon the tasks involved and in designing efficient safety programs

based on injury prevention capability. Enhanced resource alloca-tion to control injuries while performing activities with high riskprofiles will be facilitated based on the risk quantification concept.For instance, while operating equipment in the vicinity of power-lines, the use of barriers and signs may serve as an indicator ofthe presence of an active hazard which may help prevent incidents.The framework created for decision making, also incorporates thecost of the strategies, which will allow for rational decisions basedon the resources available and the financial implication of injuryprevention measures.

Finally, several researchers have proposed that tasks executedconcurrently in a worksite may increase the base-level risk (Leeand Halpin, 2003; Sacks et al., 2009; Rozenfeld et al., 2010; Hallo-well et al., 2011) and likewise the synergistic effect of injury pre-vention methods may enhance safety performance (Hallowellet al., 2011). Thus, it is suggested that future research be conductedin establishing the risk interactions between different activitiesand injury prevention methods. Also, studies that include the socialbenefits obtained through injury prevention may need to be ex-plored in the design of safety programs.

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