IChemE SYMPOSIUM SERIES NO. 153 # 2007 IChemE

TERRORIST ACTIONS IN THE TRANSPORT OF DANGEROUS GOODS IN URBAN AREAS

Roberto Lisi1, Giuseppe Maschio2 and Maria Francesca Milazzo1

1Dipartimento di chimica Industriale ed Ingegneria dei Materiali – University of Messina, Salita Sperone 31, 98166 Messina – Italy;

e-mail: roberto.lisi@unime.it, mfmilazzo@ingegneria.unime.it2Dipartimento di Principi e Impianti di Ingegneria Chimica – University of Padova, via F. Marzolo 9 Padova – Italy;

e-mail: giuseppe.maschio@unipd.it

Recent historical events have shown that the number of terrorist actions has increased in these last

years, furthermore the analysis of accidental scenarios caused by terrorist attacks or sabotage during

the handling and the transportation of dangerous goods shows a significant number of this type of

event.

In the past the hypothesis of terrorist attack or sabotage had an almost negligible value and, gen-

erally, these events were considered security themes rather than safety matters, today, the value of

the frequency for such an � accidental scenario� has become significant. Therefore it is obvious

that a complete risk analysis must include the potential scenarios caused by terrorist attack or

sabotage and therefore it must evaluate the increase of the risk level due to these events.

As well as chemical plants and storage tanks, characterized by the presence of large quantities

of dangerous substances, also road/rail tankers used for the transport of such goods constitute a

potential target, moreover the hazard associated with transportation depends on the vulnerability

of the territory.

This paper focuses attention on the description of a methodology for the analysis of incidental

scenarios caused by terrorist attacks and the identification of some aspects to improve. Finally

an application of this method has been shown.

Furthermore in order to obtain a complete risk analysis, it is necessary to take into account

that, beyond substances transported, the consequences depends on the modality of the attach, the

characteristic of infrastructure and territory.

KEYWORDS: terrorism, sabotage, transport, dangerous goods, risk analysis, accidental scenario

SECURITY AND SAFETYAs a result of the events happened on the 11th of September2001 the international legislators considered necessary todevelop and implement security measures in particular forall the activities involving the handling and the transpor-tation of dangerous goods on road, railroad and navigableways with the aim to fight possible terrorist actions.

The main objective of this paper is to combine secur-ity and safety in order to study these events which can regardboth the topics.

The topic of security is to prevent actions such asthefts, sabotage, intrusion, etc. and generally security ismanaged with both physical measures and procedures thatallow to defend the patrimony from illegal actions.

Safety mainly regards the risks associated withanthropic activities (production, handling, storage and trans-port of dangerous substances); therefore it aims to identifyand prevent all the potential undesired events due to errorsor unexpected failures, causing process deviations, and tocalculate the frequencies and the consequences of theseevents. Thus safety is managed with preventive and protec-tive measures, usually technological procedure, that allow todefend the things and the population.

In this context, the work tries to determine an effec-tive approach that allows to measure the possible damagesdue to a terrorist action during the transport of dangerous

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goods (safety) and gives some fundamental elements formore effective actions of prevention and protection (secur-ity) for people who has the task to manage such aspects.

A REVIEW OF INCIDENTAL SCENARIOSChemical industries classified at major hazard can beconsidered terrorist targets, therefore their locations areparticularly confidential, while the analysis of the possibleincidental hypotheses and the adoption of systems of pre-vention and/or protection for the safeguard from theseevents are indispensable.

It must be paid particular attention on the hazardassociated with transportation, which can be greater thanthat associated with chemical plants, because it dependson the vulnerability of the territory.

In these past few years the “terrorism risk” hasbecome, probably in world-wide within, one of the mostimportant risks to prevent and to fight. The event of the11th September 2001, the attack to the Twin-Towers andthe Pentagon, has had a determinant role in defining ulteriorprescription against terrorist actions, in particular when thepresence of hazardous goods or substances can be used forthese purposes.

There are also other meaningful events that havetaken place in the transport, in particular the incident of

IChemE SYMPOSIUM SERIES NO. 153 # 2007 IChemE

the 11th March 2004, this happened in the railroad ofMadrid and is considered one of the most serious of thehistory. There were a series of explosions aboard a trainand in some railway stations, with a total budget of 198died and 1274 hurts.

Finally it is necessary to mention also the accidentalscenarios caused by terrorist attacks or sabotage duringthe handling and the transportation of dangerous goods. Inthis context it is necessary to remember what have occurredon the 22nd July 2005 in Iraq. There was a very serious ter-rorist action, an attack caused the explosion of a road-tankertransporting gasoline, while it was parked near the SciiteMosque of Musayyib, south of Bagdad. At least 60 deadand 82 injured were reported; witnesses spoke of an apoca-lyptic scene where parents threw their children from thewindows of burning buildings in order to try to save themfrom the fire caused by the explosion.

THE ANALYSIS OF INCIDENT SCENARIOS

DUE TO TERRORIST ACTIONSThe management of the risk terrorism is very complex, itrequires a systematic and structured methodology thatallows an exhaustive analysis of the possible modalities ofattack and the definition of the vulnerabilities for the inter-ested system.

The main objective of this paper is to outline anapproach for the analysis of incident scenarios generatedfrom terrorist attacks in the transport of dangerous goods(reference), this method will be a useful support in orderto define the best actions for the prevention and mitigationof the terrorist attacks.

The complexity of the analysis of incident scenariosdue to terrorist actions obliges to apply an approacharticulated according to the following scheme:

– Characterization of the area considered potential targetregarding terrorist actions;

– Definition of the characteristics of the area (manufac-turer site and/or characterized by transport of dangeroussubstances);

– Qualitative study (identification of incidental scenarios);– Quantitative study of the incidental scenarios.

The first and the second phases of the method regardthe census of all the information characterizing the area inwhich there is the potential terrorist target, such as a manu-facturer site which can also be characterized by transport ofdangerous substances. These steps comprises therefore thecollection of the information regarding chemical plantsand the associated transport.

IDENTIFICATION OF POTENTIAL TERRORIST

TARGETSThe aim of a sabotage or a terrorist attack is to produce thegreatest possible damage, for this reason it is more effectivethe greater is the quantities of released substances in relationto the initial cause of the scenario.

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Generally the sites, considered potential target, arecharacterized by some strategic elements, these can be sum-marized in the following points. Obviously this list shows asufficient number of elements but it is not exhaustive:

– Public building– Areas with a great presence of people for particular events– Public transport systems– Telecommunication systems– Electric network, gas network, etc.– Areas characterized by a high economical impact– Areas characterized by a high historical importance– Areas of high communicative impact.– Handling and transporting activities of dangerous

substances

DESCRIPTION OF INCIDENTAL SCENARIOS FROM

TERRORIST ATTACKSRecently it has been proposed an approach (Lisi, 2006)which allows the description of the sequence of events fol-lowing a terrorist action. This approach has the aim ofdescribing the overall scenario, defining the evolution ofsuch actions starting from the initial cause and finishingwith the final catastrophic event, thus the overall scenariocan be studied considering it a sequence of simple steps.

The proposed approach for the analysis of accidentalevents from terrorist attacks is outlined in the scheme shownin the figure 1.

The study of the incidental scenarios caused by sabo-tage or terrorist attack can be made by considering thesephenomena as primary events whose consequences hit atarget. The hit target generates a secondary event which isable to widely spread the hazardous consequences of thefirst one.

The primary event causes the release of a greatamounts of energy or toxic substances, thus the final conse-quences cause serious effects to the population, infrastruc-ture and environment.

This approach allows to identify and characterizethe incidental scenarios due to terrorist attacks, that isfundamental for the successive phase of work in which theemergency measures will be identified. These measuresmust be developed on the basis of the typology of incidentand the entity of the risk.

QUANTITATIVE RISK ANALYSISQuantitative risk analysis including terrorist actions can beexecuted using the classical procedure adopted for chemicalplants and transport of dangerous goods (CCPS, 1995 andAdvisory Committee on Dangerous Substances, 1991), fur-thermore this methodology must take into account also thescenarios caused by terrorist attacks and therefore it mustquantify the increased risk due to this type of events.

This methodology must include the following phases:

– Frequency evaluation for the primary event;– Frequency evaluation for the overall scenario;– Consequences evaluation for the overall scenario.

Primaryevent

Secondaryevent

CONSEQUENCES Target

MORE SERIOUSCONSEQUENCES

Population,infrastructure,environment

Figure 1. Evolution of terrorist actions

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Taking advantage of the approach proposed in theprevious paragraph the quantitative risk analysis can besimply executed.

Frequency evaluationThe frequency evaluation involves the following phases:first the frequency of the primary event should be estimatedusing data regarding this kind of event that have happened,then it should be necessary to calculate the probability ofsuccess of the terrorist action and thus the frequency ofthe overall scenario could be defined according to the prob-ability theory.

Frequencies evaluation is important because thephase of prevention is related to the determination of thelikelihood that such events occur. Unfortunately, today,these are still not correctly estimable, this represents alimit of the proposed approach (Lisi, 2006).

As described before, the main problem is thatdata collection regarding incidents caused by terroristattacks, this does not permit an accurate frequencies evalu-ation not even through the consultation of governmentaldatabases. Moreover due to the phenomenon com-plexity, in terms of typologies of targets and geographicareas interested, the escalation of a terrorist action isvery unforeseeable, for this reason it is not possible tomake a correct analysis using the classic methodology ofthe safety.

Also using advanced techniques such as neural nets,fuzzy logic, etc., whichever simulation would provideresults characterized by excessive uncertainty and,however, these would not be improving for the final goalwhich is the protection of potential targets.

A much more effective approach could be the defi-nition of probability classes for the primary event relativelyto the targets. Probability classes could be obtained on thebasis of the available data, collected using governmentaldatabases. Such classification, written up as tables, can beused together with the results of the consequences analysisof the incidental scenarios and would allow to define anindex of risk. This index could be useful in the phases of

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emergency planning and location of the protection measuresfor the possible targets.

Consequences analysisThe consequence analysis aims to quantify the negativeimpacts of the likely events, the consequences are normallydetermined in terms of the number of fatalities, althoughthey could also be measured in terms of the number of inju-ries or the value of the property lost.

The consequences estimation consists in the damagezones identification. The effects of the incidental eventson the territory have a decreasing magnitude of the effectsin relation to the distance from the origin point, based onthe typology of the effects the territory is divided in thefollowing zones:

“Zone of sure impact” (RED ZONE): characterizedby a high percentage of fatality for the persons.

“Damage Zone” (ORANGE ZONE): characterizedby possible serious and irreversible damages for thepersons who do not assume the corrected measures ofself-protection and also by possible fatality for more vulner-able persons.

“Attention Zone” (YELLOW ZONE): character-ized by light damage also for vulnerable subjects.

CASE STUDYThe proposed methodology has been applied to an area,whose characteristics allows to carry out the followingconsiderations.

The case study refers to real situation its location isanonymous. It is an urban area at high density of population,with a meaningful number of vulnerability centres distribu-ted along the main routes of connection by road. Chemicalplants and storage tanks are not present in this area,however, a huge number of road-tankers transportingdangerous substances crosses the downtown, for thisreason the area is characterized by high level of risk.

The route under investigation, is the connectionbetween the main urban road and the highway exit, it is

Table 1. Threshold values and damage zones

Zone I

Zone of

sure impact

Zone II

Damage

zone

Zone III

Attention

zone

Concentration C � LC50 IDLH � C

, LC50

C , IDLH

Chlorine

(dispersion)

High

fatalities

Irreversible

damages

No effects

or light

effects

Overpressure Dp � 0.3 bar 0.07 bar �D

p, 0.3 bar

Dp , 0.07 bar

Liquid

fuels

(VCE)

High

fatalities

structural

damages

Fatalities

and serious

damages

No effects

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characterized approximately by a number of 1.200 vehicles/hour, this meaningfully increases the number of the subjectsexposed to potential incident scenarios.

As described before the high density of population,the characteristics of the routes (strong slopes and twoseparate tracks) and the presence of a great number ofcentres of vulnerabilities distributed along the main routesof transport are some of the meaningful characteristicsconcurring to consider this area as a potential target ofterrorist attacks.

IDENTIFICATION OF CRITICAL AREAS AND

SCENARIOS DUE TO TERRORIST ACTIONSThe identification of the critical areas relative terroristactions can be made on the basis of a census of thesubstances and the targets.

. Census of the substances obtained on the basis of thetype of hazard and of the quantities of dangerous pro-ducts present in chemical plants, storage and transport,it is possible to identify the worst substances thatcould be involved in an attack.

. Census of the targets obtained on the basis of thedangerous substances, the quantities, the operating con-ditions and the territorial vulnerability, it is possible toidentify all potential targets.

In order to mitigate the effects of the incidental scen-arios it is necessary to define the damage zones and toproduce a map of the effects. In this study attention hasbeen focused on two typologies of incidents, toxic disper-sions and explosions, since these can be considered themost catastrophic events.

According the census of dangerous substances andof targets, the critical areas are localized as shown in thefigure 2, where each point represents a potential localizationfor incidents.

Figure 2. Critical areas and loca

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In this paper the study has been focused on the studyof chlorine and liquid fuels releases. The damage zones havebeen identified using the threshold values of table 1 andthey have been represented in the figure 3a/b.

On the basis of threshold value of table 1, the follow-ing table shows the number of vulnerable centres andpeople involved in a potential incident for each criticalpoint identified above.

CONCLUSIONSThe problem presented in this paper is actually of greatinterest, because in these recent years the areas susceptibleto terrorist attacks have been widening.

The methodology applied in this work has the aim ofoutlining the scenario associated with a terrorist attack orsabotage.

The case study is a city characterized by the transportof a high quantities of hazardous materials. Even if it may

lization of potential incidents

Figure 3. (a) Effects of a catastrophic release of chlorine; (b) effects of a catastrophic release of liquid fuels

Table 2. Number of vulnerable centres and people involved (fatalities and injuries) in a potential incident

Point 1 Point 2 Point 3

Chlorine toxic

dispersion

8 vulnerable centres

17997 people

22 vulnerable centres

25179 people

13 vulnerable

centres 9852 people

Liquid fuels

VCE

2 vulnerable centres

8948 people

12 vulnerable centres

12378 people

6 vulnerable centres

1551 people

IChemE SYMPOSIUM SERIES NO. 153 # 2007 IChemE

not be the principal object of a terrorist attack, this kind ofcity has all the characteristics of a potential target in termsof territorial vulnerability. The high number of road andrail tankers transporting dangerous goods in the urban areaand the presence of numerous vulnerable centres along themain transportation routes are typical of areas subject to ter-rorist attacks.

This study has provided the damage curves that wouldderive from incidental scenarios caused by terrorist attacksfor the examined area. The effects map can constitute animportant source of information for who has to enactspecific emergency plans of civil defence and, moreover,also for who has to apply protection and/or mitigationmeasures for the exposed population.

The damage curves also allow considerations to bemade regarding possible alternatives in the transport ofdangerous substances using different routes in differenttime of day.

In particular in this study, it has been suggested thecontinuous monitoring of road/rail tankers and the typolo-gies of substances crossing the urban area. This is possibleusing appropriate control systems located at the motorwayexit and the ferry terminals or at critical points presentalong the main routes used for the transport of dangerousgoods.

Finally, emergency plans must be update and per-formed taking into account the vulnerability of the territory

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and they must include the definition of services, proceduresand emergency resources. Emergency plans have to beperiodically tested in order to verify their validity.

The methodology applied requires to be implementedin order to improve the use of safety methodology also forsecurity problems. In this work it has been suggested tofocus future studies on the problem of frequencies. Thus ithas been proposed the definition of probability classes forthe primary event relatively to the targets which, combinedwith consequences results, permits the identification indexesof risk. This index could be useful in emergency planningand for the location of the protection measures for thepossible targets.

REFERENCESCCPS, 1995, Guidelines for chemical transportation risk analy-

sis. AIChE, New York, USA.

Advisory Committee on Dangerous Substances, 1991, Major

Hazard Aspects of the Transport of Dangerous Substances.

HM Stationery Office, London, Great Britain.

Lisi R., Maschio G., Milazzo M.F., 2006, Analisi di scenari

incidentali originati da attacchi terroristici nel trasporto di

merci pericolose. Conference VGR 2006, “Valutazione e

Gestione del Rischio negli Insediamenti Civili ed Indus-

triali”, Pisa Italy, October 2006.