Environmental Engineering Reference
In-Depth Information
Undesired Outcome
Harmful
Energy,
Condition,
or Hazard
Exceeded
or Failed
Barriers
and
Controls
Person
or Object
Affected by
Harmful
Energy
Event
Event
FIgure 9.1
An. event. and. causal. factor. tree. (chart).. (
Source:
. Courtesy. of. the. National.
Aeronautical.and.Space.Administration.)
identify.an.accident's.causal.factors,.which,.in.turn.once.identiied,.can.be.ixed.to.
eliminate.future.accidents.of.the.same.or.similar.nature.
On.the.downside,.causal.factor.analysis.is.time.consuming.and.requires.the.inves-
tigator.to.be.familiar.with.the.process.for.it.to.be.effective..As.can.be.seen.later.in.this.
chapter,.the.accident.scene.may.need.to.be.revisited.a.number.of.times.and.areas.that.
are.not.directly.related.to.the.accident.may.need.to.viewed,.in.order.to.have.a.complete.
event.and.causal.factor.chain..It.requires.a.broad.perspective.of.the.accident.in.order.
to.identify.any.hidden.problems.that.would.have.caused.the.accident.
determInIng cAusAl FActors
The.collection.of.facts.should.begin.immediately.after.an.accident.occurs..Start.with.
an. accident. site. walk-through,. interviews,. and. actual. physical. material. collection..
This.will.increase.the.accuracy.of.the.information.that.is.collected.and.help.eliminate.
any. uncertainty. or. vagueness.. It. will. also. help. when. it. comes. time. to. put. together.
the. event's. causal. factor. chain.. At. this. stage,. the. details. will. prove. necessary.. It. is.
important.to.have.as.much.information.as.possible.in.order.to.have.an.ideal.accident.
investigation,.including.the.events.and.the.conditions.at.the.time.
D
irECt
C
AusEs
Direct. causes. are. the. basic. contributing. factors. that. directly. cause. the. accident. to.
occur..For.example,.it.might.be.determined.that.the.immediate.events.or.conditions.
leading.up.to.an.accident.might.be.traced.to.the.explosion.of.a.pressurized..vessel..The.
direct.cause.should.be.stated.in.one.sentence..Then.briely.explain.what.happened..
A.direct.cause.would.be.the.release.of.energy.or.hazardous.material..(Examples.of.
the.release.of.energy.and.examples.of.hazardous.material.can.be.found.in.Chapter 7.).
Another.example.of.a.direct.cause.statement.would.be:.“The.electrician.made.con-
tact.between.the.metal.rod.and.the.exposed.220-volt.wire.”.State.the.cause.as.simply.
as.humanly.possible.
Identifying.the.direct.cause.of.an.accident.is.optional.because.it.is.not.necessary.
to.complete.a.causal.factor.analysis..However,.the.direct.cause.should.be.identiied.
