Type of Document Thesis Author Roth, Jason P URN etd-04082004-121634 Title Decision Support System to Rank and Evaluate Crash Attenuators Degree Master of Science Department Civil and Environmental Engineering, Department of Advisory Committee
Advisor Name Title Lisa Spainhour Committee Chair John Sobanjo Committee Member Primus Mtenga Committee Member Keywords
- Decision Support System
- Crash Cushion
Date of Defense 2004-04-01 Availability unrestricted AbstractUnderstanding the behavior and performance of roadside safety devices, such as guardrails, concrete barriers, end terminals, and crash attenuators, is of great importance to improving the safety of roadways and intersections. Crash attenuators have saved numerous lives by reducing the severity of vehicle crashes. However, while a great deal of crash test data exists on barriers and end terminals, information on their performance under field conditions is limited. Because of a variety of reasons described in more detail below, the field performance of barriers and attenuators can vary drastically from their behavior during crash tests.
Four research objectives were established for this project. They are as follows:
1) Develop a database system.
2) Design and implement a framework for a Decision Support System (D.S.S.).
3) Input the appropriate data from FDOT into the database.
4) Use the D.S.S. and data to rank and evaluate attenuators.
The DSS is a computer program, based on a decision tree, which recommends an action that best meets a set of prioritized goals. The designer specifies goals, measures (criteria by which the goals can be quantified), and alternates (different ways in which the goal can be met). Weights are used to prioritize or indicate the relative importance of each goal and measure. They are also used to indicate the degree to which each alternate meets the objectives.
A series of graphs were developed to explain and compute the relationship between each DSS site criteria and the relevant site characteristics; these graphs are known as the importance functions. The importance functions range from zero (meaning that the site characteristic is not relevant at all for the given value of the DSS criteria) to one (meaning that the site characteristic is very important for the given value of the DSS criteria). In some cases, the graphs were developed based on numeric evidence found through researching accident reports, roadway design and attenuator selection standards, and other relevant literature. For relationships where numeric values could not be found, common sense was used to develop the graph.
Based on the test cases included in Chapter 5 and other test cases that were run, the Decision Support System does work and recommends different attenuators to meet different site characteristics and/or situations. It was determined that the Decision Support System results are more sensitive to changes in the objective weights and test standards and not so sensitive to changes in the site characteristics. The only time there were significant changes in the recommendations based on site characteristics is when the type of site was drastically changed. In the case of a mild site, based on the current setup, the recommendation could be that an attenuator may not be needed. Therefore, the importance functions should be fine-tuned to help in different recommendations.
Another recommendation is that more data needs to be added to the database. This could help give better or more accurate recommendations, since the recommendations are based on historical performance data. More historical data is required on attenuators that meet the NCHRP-350 standards. As with any program that gives results based on its database, the more data that is available the more accurate the results will be.
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