County of Stockholm
Patrik Dahlberg Daniel Maria
Introduction
Transportations of dangerous goods are necessary for the society, in the same time as they constitute a risk. An accident where a transport of dangerous goods is involved could generate a release of dan-gerous substances. This could have a negative impact on the surrounding environment and peo-ple.
This study covers the dangerous goods transpor-tations on railway and roads within the region RSN. The aim of the study has been to create a general method for the calculation of risks associ-ated with the transportation of dangerous goods.
The goal of this study has been to perform indi-vidual and societal risk calculations on particular locations, called hot spots, with help of present statistical data and information. Further more the methods applicability and signification in the risk management process have been illustrated. A discussion about the law’s interpretation and ap-plicability in the process of risk management has also been driven.
The study covers a large geographic area, which is approximately 4000 km2. Consequently to ac-complish the study one must make several de-limitations:
The study has only regarded the transporta-tions by road and railroad.
The study does not considerate the impact on buildings and fauna that the release of dan-gerous substances have.
The calculations for the release of a dangerous substance are based on the assumption that the weather always has the D stability class and the wind velocity is always 4 m/s. This assumption is base on the fact that these pa-rameters are most likely to occur in the re-gion.
The calculation models for risk-distances and risk-areas are based on assumptions and delimitations made on sizes of holes, type of release, etc. Therefore the result of these calculations must not be regarded as the absolute truth but only as rough estimations.
Goods vehicles and cistern wagons are custom adjusted, thus there is no standard for those. The sizes of the cisterns and tanks have been chosen as a mean value from known constructions.
The study does not regard the transportations of mixed cargos. The amount of transported goods has been calculated from chosen tank-sizes and the SRV’s survey on the goods flows within the region.
The hot spot conception
A hot spot is defined as a place with a high frequency of accidents and there severe conse-quences for the surroundings from an eventual release of a dangerous substance can occur.
Studying existing statistic data of transportation flows within the region and accidents related to the transportation of dangerous goods has been used as a method for the identification of hot spots. The material covering the accident- statistics has been used for the calculation of likelihood and frequencies of an accident within the region.
As a complement to this work an inquiry about which places are specially affected by accidents or which places are particular sensitive in the event of an accident with dangerous goods, has been sent to all fire departments within the region. Further more interviews with key persons in the work area of dangerous goods have been conducted.
The identification process of hot spots has also covered a research of map material from VV and SRV. VV’s maps represent the recommended roads for transportation of dangerous goods and give important information about how the roads are reaching through sensitive ecological areas or high-populated areas. The amount of dangerous goods transported by roads, sorted by class, has been estimated by using SRV’s maps of transports flows.
Figure 1, The 26 hot spot sites in the region RSN The identification work has been compiled as a hot spot list consisting of 26, see figure 1, differ-ent places of interest. By using a rough selection four places have been chosen for a more pro-found risk analysis. The places are: 1 the harbor of Kapelskär, 9 the high-populated area of Rimbo, 18 the train station in Rotebro and 25, Arlanda city
Work method
Figure 2 represents the work method of this study.
Conclusions
The chosen sites for this study generate high levels of societal and individual risk. It is of great
interest to note that the results of this study should not be treated as the absolute truth.
The results of this study should be used only for the purpose of comparing the risk situa-tions between different sites. For example: Are the individual and the societal risk levels higher in Arlanda city compared with Rimbo?
The high levels of individual and societal risks are motivated by the assumed high frequency of dangerous goods transportations through the chosen sites. There has been no consid-eration taken for factors that can influence the traffic safety such as: traffic signs, road width, etc. The method gives a clear and easy to un-derstand result which can be used as a tool for comparing different effects of risk reduction actions.
Risk analysis of transport of Hazardous material in the county of Stockholm
The study has resulted in a general method for the calculation of risks which at the present time is a rough tool. The method is based on assumptions and simplifications which propagate through the calculations and affect the results. A lack in the calculation model is that it doesn’t take in consid-eration the transit transports through the region because of tha lack of information about those transports. Those transports should be registered to appropriate instance so that usable
information can be accessed and in this way make the model in this study a better tool for risk cal-culations.
The biggest difficulty in this study has been gath-ering useful statistical data, for example the distri-bution of chemicals within chemical classes or the amount of transported chemicals. This lack of information can be related to different market actors and their fear of be associated with risks.
To create better conditions for better risk analyses and studies on the risks associated with the trans-ports of dangerous goods, should the instances involved in the transportation of dangerous goods be imposed by the law to leave useful information.
There are approximately 25 laws that are treating the dangerous goods. Only two of these laws treat the dangerous goods transports specifically. This could be interpreted as if the transports of dan-gerous goods are not related to accidents in the same perspective as factory premises that are han-dling dangerous substances. Several statistical reports show that the biggest releases of danger-ous substances, in the latest years, came from accidents where
dangerous transports were involved. An im-provement of the present situation could be achieved through a law change, for example the environment code could be change so that includes the transports of dangerous goods.
Unfortunately it is often that it takes an acci-dent to happen to achieve a law change. For example it could be mentioned that the Seveso directive came as result of a chemical catastro-phe. The law changing process is also long from a time perspective. A interpretation of an existing law is definitely a faster and more appropriate method for achieving changes. A parallel could be drawn from Malmö fire de-partment’s interpretation of RtjL 41§. Malmö fire department has chosen to interpret the law text as every apartment in Malmö must be equipped with smoke detectors. As result of this action 95 percent of Malmö’s apartments have smoke detectors. The law interpretation has led to a powerful reducing of the death casualties from apartment fires.
Similar interpretations could be made for the dangerous goods transports. In several law text it is mentioned that the urban and rural districts must take measures to prevent, limit or eliminate damages and risks on the envi-ronment end people. To accomplish that it is essential that information about the dangerous goods transports in the society is easily reached. It is of great importance that the law instances impose an information responsibility on those who handle the transportation of dangerous goods.
Consequence calculations Risk distance
Risk area Number of Casualties
Researching site specific information Accident statistics
Transportation flows Type of transported substances
Risk calculations Individual risk
Societal risk
Probability calculations Accident frequency
Event tree analysis
Conclusions and discussion Risk management Risk reduction actions
Risk Assessment at DuPont Chemoswed and an analysis of how risk can be presented and evaluated