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78 CHAPTER 15 Conclusions Damage to a longitudinal roadside barrier is not always Five tort cases and one documented crash found in the characterized by the large rail deformations and sheared posts literature show that impacts with previously damaged bar- characteristic of a high severity crash. Much more common riers do occur in the field. is minor damage such as a shallow dent which is a result of a low-speed collision or sideswipe. Unfortunately, the effect of A survey was distributed to the State and Canadian Provin- this minor damage on the performance of the barrier in sub- cial Transportation agencies to ascertain current practices sequent impacts is not well understood, and there is little bar- with respect to the repair and maintenance of longitudinal rier repair guidance available for highway personnel tasked barriers. Based on the responses of 39 agencies, the research with maintaining these systems. team has the following conclusions: The goal of this research project was to develop guidelines to assist highway personnel in identifying levels of minor bar- Two-thirds of responding agencies indicated more quan- rier damage and deterioration that require repairs to restore titative guidelines for the repair of guardrails would be operational performance. The focus of the project was on the beneficial. length of need of w-beam barriers. This chapter presents the Approximately 60 percent of responding agencies reported conclusions of the project including (1) current practices for specific guidelines for when to repair damaged guardrail. repairing damage to longitudinal barriers, (2) the approach to Less than one-third of these agencies indicated tangible and develop objective criteria for measuring damage to longitu- numeric criteria to identify when barrier repair is necessary. dinal barriers, (3) the approach for quantitatively evaluating Half of the top 10 damaged barrier modes deal exclusively these guidelines, and (4) the recommended guidelines with with the w-beam rail element. threshold values for which barrier repair is recommended. Post and rail deflection in excess of 6 inches is found to be the most prevalent type of guardrail damage; however, this damage is generally classified as moderate damage. Of the 15.1 Summary of Current Practices minor damage modes, rail deflection only, post and rail de- Current practices and research needs were determined based flection (< 6 inches), and rail flattening are most common. upon the results of a literature review and a survey of State Repair priority is found to be high for post and rail damage and Canadian Provincial transportation agencies. A literature greater than 6 inches, rail tears, cable damage, w-beam splice review on the repair and maintenance of longitudinal barriers damage, and loss of tension in the cable barrier. revealed the following: 15.2 Method of Evaluation There appears to be no scientific basis for the existing of Guidelines national guardrail repair guidelines. Current guidelines appear to be based exclusively on engineering judgment. A set of target damage modes was selected for evaluation With the exception of a select few state agencies, a majority based upon the results of the survey of U.S. and Canadian of state agencies with published barrier maintenance guide- transportation agencies, and inspection of a catalog of minor lines or rating schemes lack quantitative descriptions and barrier damage categories. Target damage modes were selected examples of deficient barriers. based on their frequency of occurrence and perceived threat to