RISK-BASED TRANSPORTATION PLANNING ...

RISK-BASED TRANSPORTATION PLANNING PRACTICE: OVERALL METIIODOLOGY AND A CASE EXAMPLE"' ERTUGRULALP BOVAR-CONCORD Etwiromnental, 2 Tippet Rd. Downsviel+) ON M3H 2V2 ABSTRACT We are faced with various types of risks in our everyday lives and continue to be exposed to new risk sources. Decision makers are contin ual ly faced with deciding whether a new risk source should be allowed in a particular community. Before making such decisions, it is desirable to know what the existing risks are, and what additional risks a new facility would bring. Then, if there are established guidelines for risk acceptability, planningdecisioru> can be made so that some segments of the society are not exposed to unduly high risks, especially risks over which they may have very little control. Quantitative risk assessment (QRA) techniques are playing an increasing role in analyzing safety of industrial gystems, such as transportation networks or fixed industrial facilities. The present paper discusses the commonly used QRA techniques and provides a review of measures of risk. ac­ ceptability. Particular emphasis is given to the fundamentals of quantifying risks near transporta­ tion corridors, which are linear risk soun:es as opposed to the more familiar fixed point sources of risk. The methods are demonstrated through a real life example: assessment of risks due to rail transportation of dangerous goods in the Greater Thronto Area. Where appropriate, comparisons are made witlJ recent transportation routingliterature. Recommendations are provided for further research.

Keywords: Risk-based planning, risk assessment, transportation

RESUME Nous faisons face quotidiennement a plusieurs types de risques et sommes continuellcment sujets a etre el!poses a de nouvell es sources de risq ues. Les preneurs de decisions doivent fnlquemment d6cider si une nouvelle source de risque peut eire implementee dans une communaute. Avant de prendre une telle decision, iJ est desirable de connaitre les risques existants au sein d'une com­ munaute et quels risques additionnels un nouvel etablissement apportera. S'il existe des directions prcciscs concernant le niveau acceptable de risques, les decisions de planification peuvent etre prises afin que chaquc segment de Ia population ne soit pall expose a des niveaux de risques trop elevees. Ces decisions sont davantage importantes lorsqu'il s'agit de risques sur lesquels Ia population a peu de controle. Des techniques quantitalives d'evaluation des risques (EQR) jouent un role d'importance grandissante dans !'analyse de Ia securite des systernes industriels, comme les reseaux de transport el les etablissements industriels fixes. Le present article discutc lcs techniques EQR frcqucmmcnt utilisecs ct prcscnte un sommaire des mcsures de risques acceptables. Une attention particuliere est donmle aux principes fondamentaux de Ia quantification des risques pres des corridors de trans­ port car ces risques cnnstituenr des sourceslineaircs de risque plutot que des sources habitucllcs de risques fixes. Les methodes sont presentees avec l'aide d'un probleme reel: I'evaluation des risque s que re pres ente le transport des matieres dangereuses via le reseau de transport ferroviaire dans le Thronto Metropolitain. Lorsqu'elles soot uppropriees, des comparaisons sonl fuiteli uvec des pub­ lications recentes concernant le transport. Des recommandalions sont presentees pour de futurs projets de recherche.

l. INTRODUCTION 1.1

Types ofRisk

The wor d "risk" can take on very different meanings for different people an d also depen ding on the conl�.;xt of a p