The objective of this study was to develop guidelines for the use of guardrail on low-volume roads (LVR) in Kansas according to safety and cost effectiveness. LVR are generally defined as roads with less or equal 400 average daily traffic (ADT), although many LVR’s have much lower ADT’s. It should be noted that the term “guardrail” means some sort of restraining device to keep errant vehicles that leave the roadway from crashing into a more dangerous roadside environment. Roadside is defined as the area beyond the travelled way and the shoulder (if any) of the roadway itself. Most experts prefer the term roadside barrier or “barrier rail.” Others (as is the case with KDOT personnel) prefer the term “guard-fence” as being more general. Most local road personnel use the term guardrail. In this report the term guardrail will be used. A comprehensive review of the research literature was conducted to explore and gather information on the use of guardrail on LVR according to safety and cost effectiveness. The purpose of this information search was to identify the general elements used to determine the need for guardrail on LVR and to review any specific guidelines already in use by other states. The principle findings from this literature review are presented in this report. The computer program ROADSIDE is widely used to assist designers in making informed choices regarding alternate guardrail design concepts. ROADSIDE follows the Roadside Design Guide cost-effective methodology. The ROADSIDE program was adapted to Kansas LVR parameters. The ROADSIDE program was used to develop guidelines to determine whether guardrail is needed on fill embankments and for shielding roadside obstacles on secondary roads. The results are presented in this report. It is recommended that KDOT consider endorsing the guidelines developed in the report to assist counties in evaluating the need for guardrail on their LVR. (A)
Abstract