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CHAPTER9

Barrier Analysis

0 ne of the most important purposes of a safety program is to identify hazards and establish barriers that will keep hazards from coming in contact 11~th workers. Barrier analysis is the identification and analysis of barriers that are associated with accidents.

There are several types of barrier analysis. Most accident investigators use hazard-barrier-target (HBT) analysis, which considers potential hazards and potential targets and assesses the adequacy of barriers or other safeguards that should have prevented or mitigated the accident (Spear 2002). Energy trace 0nd banier analysis (ETBA) and barrier and control analysis (BCA) are useful for preventive analysis. ETBA traces the energy flow or energy path throughout the system and analyzes barriers for adequacy (Stephenson 1991 ). BCA locates hazards · In a system and focuses on how to control them.

AboutB · An . arner alys1s Barrier anal · c • T ysis 1or accident investigations can be traced back to the MOR system creat db B" hni w e Y ill Johnson for the Department of Energy. The tee que

as develop d · c I

e to look at an unwanted energy flow and determine what barners ou d contain th . . reali e flow. Safety professionals and accident investigators soon ~~thMo . anal e RT system and barrier analysis could be used for reactive Yses such · . 985) as accident Investigations with excellent results (SSDC 1 ·

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Other types of barrier analyses and work h 1980 s eets wer . s and were called by different names HB1' e used In the 1970, t h · c · . · anaJys1s1sth b . 'lid ec nique ,or accident mvestigations It c b e an:ier,n,1,...

. an e used for s· - ,,. well as complex accidents to determine how th h linple accid,n~ e azard reached the

The Barrier Analysis Approach

Two products of barrier analysis-a chart and an analysis Worksheet- arc together to graphically explain accidents and analyze the barriers that

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be corrected or added. The chart illustrates hazards, barriers, and tatgeij. 11,, concept of the chart is simple: the investigator identifies a hazard and,~ and then determines the barriers that could keep the hazard from reaching the target (see Exhibit 9.1). The analysis worksheet is used to describe th, purpose and evaluate the performance of each barrier.

Exhibit 9.1Afioicj BARRIER ANALY$1S.,GRAPflW --c.

HAZARDS

)tr

B A R R I E R

. Analysis Process The Barner

9. Banier A na!ysis Chapter ·

. Chart h ard and the target. In alysts · fy the az th Barrier Ml . al sis is to identl the hazard would be . e

fbe t step in baroer : e:ployee, for exampl~he next step is to identify . 1],e firs fan electrocute uld be the employee: fi l, d barriers that 111ere the case o d the target wo f barriers-bamers that a, e , dectricil)' an ee categories o . e Exhibit 9 .2). .

brainstorrn thr that did not exist (se I d only if all barners or d bamers . be comp ete not 1111d, an f barrier analysis can . . g is a good way to · "part o d d Brainstonru.n Th "analysis . are inclu e .

e .th the accident Exhibit 9.3). associated w1 . e list of barriers (see . e the types

·e-a comprehens1v . t investigators categonz mak n safety professionals and acc1~:nhard (engineered) barrie rs and _soft

Ma y . other way as well- . 1997) Engineered barriers f bamers 10 an Safety Society · . o( d ·rustrative) barriers (Sys tem hi guards and protective eqU1pment. a rm . uch as mac ne d work are physical res tram ts s olicies and procedures-approve . . Administrative bamers are P . ntrol (SSDC 1985). Exhibit 9.4

· · nd superv1sory co d methods, job trauung, a b . that would have prevente an f b · Any arner . lists these types o arners. _ b . alysis. Categorizing barriers b . ated into arner an f accident must e mcorpor the brainstormed list o as "hard" and "soft" is a good way to structure barriers.

Exhibit 9.2

C BARRIE( CATEGORIES 1. Barriers thatfalled The barrier was in place and operational at the time

of the accident, but it failed to prevent the accident. 2 • Barriers that were The barrier was available, but workers chose not to not used use it.

;--:--__~-:----------------:-----:-:---- 3· Barriers that did The barrier did not exist at the time of the accident. -------------

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Exhibit 9.3

Barriers that failed 1.

Brainstorm the barriers tho used that failed and record ~:ere here. em

Barriers that were not used 1.

Note: The key to h. stormingsess· t. 1sbrain. Ii

10n1stot ndal/ofther. .1 'Y to or nonexistent ab1 e~ unused, n amers Do ot be co~cerned if yo~ a,

not cena,n which cat e they belong in. ,gory

Brainstorm the barriers that were not used and record them here.

Note: The difference between ;:==:--=;:_-::-::-;:;-:-----:---------_J these two categories is that Barriers that did not exist "barrierrnotused'were

Brainstorm the barriers that did not exist and record them here.

available but were not used· "barriers that did not exist'' were not available.

The short example on the next page demonstrates the barrier ana!Jsis

approach.

A worker was mowing a lawn when a rock flew out from beneath the mower and hit another worker who was walking to her car. In this example, a failed barrier is the plastic rock guard under=•

( oineered barrier). A barrier not 11sed ,s the comp y

m ower an en,,-- · when procedure that states that workers. should stop :~)~\artier

_ "-'~ b (an adrrunistrattve barn · people are wauui,g near Y dminisrracive bar-

. • h kli t/walkaround (an a d that did not exist 1s a c ec s . h k for rocks an b f, owing to c ec rier) the worker should use e ore m d and equipment

d the ground and check that all guar s h azar s on . . d O eracing, are in place, in good condiaon, an p . invescig:icio~

. d es of barriers in ever)' A ,ou caJl you will not find all ca tegones an typ e es and categones. s J

. . rirical to brainstorm all of th typ However, tt is c

Chapter 9: Barrier A11afysis

ADMINISTRATIVE ENGINEERED 1. Procedures s

I. Machine guards

H 2. personal protective 2. Training 0 equipment 3. Supervision

A J. Fall protection 4. communication F R 4. Interlocks s. Work planning T D

s. Electrical systems 6. Standards and 6. Safety valves

regulations

., in the lawn mower example, there were at least three ways this accident could have been prevented. A barrier analysis summary chart is s h own in Exhibi1 9.5. This type of chart is useful not only for fact finding and analysis, buralsofor identifyingcorrective actions. Use the chart and the last column of rheanalisis fonn to prevent recurrence of an accident.

Exhibit 9.5

HAZARD---- Flying rock

{

Rockguard BARRIERS

Procedure

Checklist/walkaround

t TARGET-- Worker

Note: One of the key 1

uses for this type of chart is to develop corrective actions. If any of these barriers had worked, the hazard (the flying rock) would nat have come into contact with the worker and the accident would not have occurred.

Part Ill: A nafytiral Ttchniques

After all barriers are brainstormed cate . . • gonzmg them way that benefits the organization It is all can be handled ·

. . usu y useful to tn any barners from administrative barriers f;or . d separate enoi" ease In evelo i ct'•~ett-d to address o r alleviate the problems E n,,;n d b _P ng corrective >cti~.

. . e,· eere arners that f . ·~ d esign problems that can be corrected by en,,; ad are usu,,c department, w hile adnurustrative barriers that fail ntenan« . . . e,·neers or the mai ---.,

are usually man system p roblem s that must be corrected by management. agcrn,n,

The Barrier Analysis Worksheet

A worksheet is u sed to analyze the performance of the barriers. Exhib1t 9 _ 6 is a sample worksheet.

• Column 1: List the barriers, as illustrated in Exhibit 9.6. They can i, lis ted b y category (failed, not used, did not exist) or type (engineered or administrative) .

Column 2: D escribe the intended function of each barrier. In the 1,-. m ower example, the guard is an engineered barrier intended to keep items

from flying out om . . . . . ull . fr under the mower deck. The procedure of stopputg . alkin. b is an administraave bamer that ,o when someone 1s w g near Y

have prevented a rock fro m hitting someone. . .

formance of the barrier. Each bamer Is • Column 3: Evalua te the per hi a target. The lawn mowa hazard from reac ng

supposed to prevent a . hi h allowed the rock to fly out guard failed because it was defecnve, w c

. S mmary Chart . ol Barrier Analysis u . list of the bacrierS assooat

. chart is slITiply a I

d workshc<L A b arrier analysis summary b generated from the compete anagem01t

. d The list can e . port or m with the ace, ent. di . to an accident re . ....,ding th< lJent ad uon · coons '•o-This chart is an exce d develop correcuve a

also be use to briefing, and it can use of barriers.

Chapter 9: Banier Analysis

B~RRIER

~barriers.

BARRIER ANALYSIS FORM

PURPOSE OF BARRIER

PERFORMANCE OF BARRIER

,. I.

2. 2. _______ _

Record the purpose of each barrier.

Analyze the performance of each

barrier. Try to focus on the effect of the barrier

on the accident or accident sequence.

Example Scenario

funieranalysis analyzes barriers that failed, were not used, or did not exist. )1011 oi the barriers in the forklift-ladder scenario either failed-supervisor 1 runing-or were not used-scheduling , a safety review, procedures ,

b1mcades, and communication. The barrier analys is form and barrier analysis 'utnmary chart are illustcated in Exhibit 9.7 and Exhibit 9.8 respectively . 8 llritt,naJ},is demonstrates that when this accident occurred, many barriers

""ltd th

at could have prevented the accident, but they were not used.

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Exhibit 9.7

BARRIER ANAL Ys1s OF

BARRIER PU

1. Scheduling and safety review

2. Job procedures

3. Barricade

4 . Communication

s. Supervisor training

BARRIER PERFORMA,.CE OF BARRIER 1- Toevatuatealljobs

and incorporate safety 1. This barn er fa iled measures to ensure the because a safety safety of Workers. review Was not

performed for thls task; perforrning it would have prornpted the worker to use the correct procedure.

2. To ensure that all personnel who perform tasks are trained and use the same sequence.

2. This barrier fa iled because upper management did not enforce procedures and the new supervisor did not use the proper procedure.

3. To wa rn forklift drivers 3. This barrier fa iled that work is being done in the aisles.

4. To ensure that all information is shared between supervisors and employees.

s. To ensure that supervisors are adequately trained on management responsibilities.

---

because the warehouse supervisor failed to barricade the aisle.

4. This barrier failed because there was no communication about the job between the supervisors.

5. This barrier failed because the new supel'\l'isor did not adequately perfo~ his supervisory doues. The culture from op~ management seems t? be "Get the job done. --

CbrlfJ/er 9: Bt1m 'er Ana(J•si.s

OF EXAIIIPLE SCENARIO £.b>"'' 9.S ALYSIS su111111ARY

RRIERAN 8.1 Hit by forklift/

~,uARD --Fall tram height

{

Review

Procedure

BARRIERS Bamcade commurncat1on

Super,,sr uam<ng

TARGET ----Worker

Summary

\.:hoogh mmy types of barrier analys is exist, all see k to accomplis h the agotl-acc1dent analysis. The hazard -barrier-targe t (HB1) type of barrier ~1m can be used on all accidents regardless of s ize . It is a very e fficient mro wlp:e smaller, first-aid-type accidents.

61Ccideminvestigations, barriers are either engineered or adminis trative . i:ry can be \1ewcd as barriers that failed, were no t used, o r did not exis t. Si.ma an1lys1s hdps an investigator to identify barrie rs, d escribe the ir f .. 7JS(, and analrze their performance. Afrc r t!Us analys is is per fo rmed , :~ be used to develop corrective actions. (Please see the Appendix fo r a

Barner Analysis fonn.)

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Part Ifl: A 11a!Jtical Tech11iques

REVIEW QUESTIONS 1. What does barrier analysis try to accomplish?

2. How can barrier analysis be used to prevent accidents?

3. What three categories should be brainstormed during barrier analysis?

4. List two types of engineered barriers and two types of administrative barri ers. s. How can a barrier analysis summary be used to recommend corrective

actions?

6. Many barriers are used when mowing, edging, and weed trimming. List all of the barriers that keep you from receiving an injury when doing yard work. Also, list any additional barriers that could be added or used that could prevent injuries from yard work.