This paper discusses the design, testing, and development of guardrail-to-bridge rail transitions. In order to solve safety problems with vehicles impacting the ends of bridge rails, a family of transition designs were crash tested with passenger cars in accordance with the recommendations of National Cooperative Highway Research Program (NCHRP) Report 230. These transition designs became widely used in the United States. However, when these same transition designs were crash tested with pickup trucks in accordance with the new recommendations in NCHRP Report 350, they failed due to vehicle rollovers. It is now evident that any or all of these transition sections may be critical, i.e., there is no single CIP. Care must be taken so that the "hard spot" is not simply moved from the end of the concrete section to another location farther away in the transition section. Small design details may be crucially important. Since crash testing is expensive and time-consuming, finite element analysis will be used increasingly in the future in order to more thoroughly evaluate transition designs and to develop improved designs. Crash-tested transition designs for TL-2, TL-3, and TL-4 are currently available. Even a TL-3 transition from a three-cable guardrail to a W-beam guardrail has been developed. Additional information about these tested transition designs can be obtained from FHWA's website. (A) For the covering abstract of the conference see ITRD no 207828. The reprints are also available at the web - http://www.vti.se/pdf/reports/K18APart1.pdf; http://www.vti.se/pdf/reports/K18APart2.pdf and http://www.vti.se/pdf/reports/K18APart3.pdf.
Abstract