Guardrail end accident analysis (FHWA-OK-92-09) 2190

This study documented attributes associated with guardrail end accidents on Oklahoma Department of Transportation (ODOT) roadways. The database which the researchers studied included accidents at a variety of guardrail end types, but most ends were either exposed or turned-down. The s everity of exposed and of turned-down guardrail end accidents in relation to lateral location of the guardrail, to vehicle rolling and vaulting, and to vehicle weight was investigated. Each acc ident report was read carefully to obtain relevant information for analyses. The results showed that on divided roads, vehicles struck median guardrail ends as often as right-side ends. On undivided roadways, right-side ends were struck 60% of the time. Fatalities or incapacitating injuries occurred in 1/6 of the end accidents. The vehicle vaulted or rolled in about 1/4 of the guardrail end accidents. The research indicated that turned-down guardrail end accidents had more vehicle rolling and/or vaulting than did exposed end accidents. Driver inattention was a factor in 1/3 of all guardrail end accidents. The majority of guardrail end accidents on the state system occurred on a small portion of the system, namely the higher volume roadways. The researchers sugge sted that accident reporting methods be enhanced, and that rumble strips be tested as a means to reduce guardrail end strike accidents. If newer, more expensive end treatments were installed, locating the new guardrail ends on a small portion of the system could address a maj ority of the end accident sites.Final Report, November 1991-December 1992N

Expert systems applications for ODOT (FHWA-OK-91-09)

Expert systems are "intelligent" computer programs which have the capabilities of reasoning, learning, and simulating human sensory capabilities. Solutions to many problems in transportation engineering which are not well structured as well as those which do not have an explicit numerical algorithmic solution, can benefit from using expert systems. Many state transportation agencies and research institutes have shown varying degrees of interest in the application of expert systems for various problem domains. The study presented in this report was aimed at critically reviewing the expert systems in transportation engineering with an idea of examining their suitability in the OOOT environment. The study included computerized search of the databases and a telephone survey of various research institutes and state transportation agencies. The literature was reviewed based on the following factors: problem domain, data required for the system, verification and validation, stage of development, future directions, use of shelVAI language, hardware requirements, and developer/ contact person. Despite their high potential for application, it was noted that, the utilization of expert systems in many transportation engineering problems has been rather limited. The reasons for such limited use could be attributed to the lack of technology transfer from the research arena to practice, difficulties involved in knowledge acquisition for certain problems, variation in practice from one agency to the other, lack of sufficient documentation and absence of effective economic treatise to the problem. It is, however, recommended that ODOT should plan on introducing expert sysytems to maintain its competitive edge. Such expert systems could help ODOT in restoring its institutional expertise in a cost effective manner and can also serve as a training tool.Final ReportN