Qra Decision Support Model For Locating Haz Mat Teams


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  • This research was funded by the Natural Sciences and Engineering Research Council of Canada. I’d like to introduce my co-authors: Ghada Hamouda. This work is part of Ghada Ph.D. thesis and my colleague in the Dept of CE Liping Fu.
  • Qra Decision Support Model For Locating Haz Mat Teams

    1. 1. QRA Decision Support Model for Locating HazMat Teams Ghada Hamouda, Frank Saccomanno, Liping Fu Department of Civil Engineering University of Waterloo
    2. 2. Background <ul><li>Transportation of HazMat poses special risks for population and the environment. </li></ul><ul><li>Effective location of HazMat response teams can play an important role in reducing risks. </li></ul>
    3. 3. What is a HazMat team? <ul><li>Refers to responders who are specially trained and equipped to manage and control incidents involving different types of hazardous materials (US Dept of Labor). </li></ul><ul><li>Involves a certain degree of multi-tasking, but central focus is on managing HazMat risk </li></ul>
    4. 4. Current practice: <ul><li>HazMat teams housed in existing fire stations (multi-tasking). Not all fire stations. </li></ul><ul><li>Decision is made at local level </li></ul><ul><li>Focus is on covering high population concentrations (usually near towns and cities) </li></ul><ul><li>HazMat transported in more remote areas (over 90% of the regional highway network in the US and Canada is rural) </li></ul><ul><li>Tendency not to cover marginal locations (poor coverage, high risk and cost) </li></ul>
    5. 5. Objectives <ul><li>Develop a risk-based DS model for locating HazMat teams on regional road network </li></ul><ul><li>Illustrate the usefulness of the model through case study application in SW Ontario </li></ul>
    6. 6. Risk-based DS <ul><li>Risk defined: </li></ul><ul><li> R kr = Frq kr * Csq kr </li></ul><ul><li>Expected fatalities resulting from HazMat incidents at different segments of the highway network for a given period of time (accident induced). </li></ul><ul><li>Csq kr output from “time-dependent” QRA analysis (US EPA “ALOHA model”) </li></ul><ul><li>Frq kr output from accident/release prediction model or look-up table </li></ul><ul><li>In study we do not consider: long term health and env. impacts. </li></ul>
    7. 7. Schematic of HazMat team location Fire station ( i) - potential site for HazMat team Network node ( j ) - potential demand for HazMat team Hazard area
    8. 8. Find optimal location of np HazMat teams among nf candidate nodes (fire stations), such that:: Minimize total network risk (Expected Fatalities/Yr) Ensure that maximum response time and risk at all nodes does not exceed some pre-set threshold ( T max R max ) Location Heuristic:
    9. 9. Model framework: I Yes Choose number of Hazmat unites Calculate response times from Hazmat teams to nodes Calculate time - dependant societal risk on the region Locate HazMat teams Is location strategy acceptable? Stop No
    10. 10. Case Study: SW Ontario Region
    11. 11. Estimating HazMat flows HazMat accounts for 9.9% of total truck traffic in the region (DGAIS). Applied to AADT * %Trucks to yield link HazMat flow on SW Ont network. Estimate flows by HazMat type from DGAIS percentages
    12. 12. Truck accident rates (accidents/MVKm) Highway type Urban Rural Arterials Overall 1.023 0.549 1.003 0.924
    13. 13. Accident induced release probabilities by HazMat type (%)   Ammonia Propane Gasoline Large spill 0.87 1.09 1.34 Small spill 0.44 0.55 0.73 Large leak 0.08 0.10 0.12 Small leak 0.19 0.24 0.30 Total 1.58 1.98 2.49
    14. 14. Relevant Location Issues <ul><li>How many teams to locate region-wide </li></ul><ul><li>Implications of current vs min risk strategy </li></ul><ul><li>Implications of specific closure decisions for current strategy </li></ul><ul><li>Implications of locating teams one at a time </li></ul>
    15. 15. Total risk versus no. of HazMat teams Point of inflection (Four Teams) Feasible Solutions
    16. 16. Current vs Optimum (4 HazMat Teams) <ul><li>Current strategy teams at nodes 6, 12, 15 and 22 </li></ul><ul><li>Risk minimum strategy at nodes: 6, 14, 22 and 27 </li></ul><ul><li>(Nodes 12 and 15 replaced by 14 and 27) </li></ul><ul><li>Small difference in total risk. Maximum resp. time and risk same. </li></ul>Total risk Fatality/year Max risk Fatality/year Max resp onse time (min) Current locations 0.0710 0.0105 58.8 Optimal locations 0.0666 0.0107 58.8
    17. 17. Close one HazMat team (reduce costs from current strategy) <ul><li>Best option to close Node 6 (Hamilton) results in lowest risk increase of 2.9% over the previous option </li></ul><ul><li>Next best closure of Node 12 (Burlington). More practicable (risk increase of 3.9%). </li></ul>Nodes with HazMat teams Total risk Fatality/year Max risk Fatality/ year Max response time (min) Change in Total risk Current 6 12 15 22 0.071 0.01 58.80 Closing 12 6 15 22 0.074 0.01 75.00 3.9 Closing 6 12 15 22 0.073 0.01 75.86 2.9
    18. 18. Location options for different network HazMat team totals
    19. 19. Recommendations <ul><li>Extend analysis to consider cost of new HazMat teams </li></ul><ul><li>Incorporating multi-tasking </li></ul><ul><li>Permit incidents on links </li></ul><ul><li>Incorporating personal injury and property damages (short and long term) </li></ul>