Do we need to have the vertical devices (road tubes, vertical panels, etc.) in place when crash testing a "curbing" system as a work zone device in Category II.May computer modeling be used as a substitute for full-scale crash testing of new devices?.May a decorative texture or graphic design be added to the face of a crashworthy concrete barrier?.I thought a non-gating terminal captured everything that hit it?.How high do you need to raise guardrail that is lower than 26 ½ inches? What are the best ways to do that?.When do you need to raise the guardrail when an overlay has reduced the height?.How was the 31" height selected? Did small car performance, testing, or simulation play a role?.
Would a nominal height of 29" +/- 1" with an 8" blockout be acceptable? At what height is a 12" blockout recommended? Can you adjust the simulation to test heights between 27-3/4 and 31"?.Have there been a statistically significant number of crashes and/or fatalities with the lower height rail that is driving the increase in height or is it all based on crash testing and simulation?.Will there be similar new height requirements for box beam rail?.What about the national trend to go greener and the growing preference for smaller, lower profile vehicles? Is a higher rail needed for the future?.What kind of foundation do we need for our concrete median barrier?.What guardrail hardware must be replaced or upgraded on the NHS?.How do we know that damaged barrier needs repair?.Many of our guardrail terminals have a steel bearing plate on the first post that sometimes rotates until it is upside-down.How can we design our barriers to be "motorcycle-friendly?".Can we pave a mow strip under our guardrail?ĬAN WE PLACE GUARDRAIL POSTS IN A CONCRETE SIDEWALK OR MEDIAN?.
BRIDGE GUARD RAILS PORTABLE
A similar project (NCHRP 20-7(257)) synthesizing information on portable concrete barrier shapes, connections, anchorages, and other considerations will also be completed soon.Īs noted at the end of the FAQ list, we expect to develop additional guidance in this format. Additional guidance on cable barrier selection and placement on sloping terrains and adjacent to median ditches will be provided in conjunction with National Cooperative Highway Research Project 22-25, scheduled for completion in early 2010. The Office of Safety's July 20, 2007, memorandum on Cable Barrier Considerations dealt with numerous issues of cable barrier design, selection, and placement. In general the questions relate to rigid and semi-rigid barrier systems. They are the considered opinions of engineers in the FHWA Office of Safety Design and the FHWA Resource Center with helpful input from members of the American Traffic Safety Services Association's Guardrail Committee. These questions and answers offer clarification on the use of roadside hardware for issues not covered by FHWA policy or topics that simply need additional explanation. However, FHWA field offices often raise numerous issues that involve interpretations, extrapolations, device selection, hardware deployment, or simply trying to fit safety devices into real world conditions. FHWA barrier guidance is contained in the AASHTO Roadside Design Guide.
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