Longitudinal Barriers
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This listing contains information on crash-worthy longitudinal barriers, such as guardrail, median barrier, and some bridge railings. (Additional information on bridge railings is found under that category.) You’ll also find information here on acceptable transition designs for attaching approach guardrails to bridge railings and for synthetic blocks used with w-beam guard rails in this listing. Temporary barriers used in work zones are included here as well.
NCHRP Report 350 establishes six test levels (TLs) for longitudinal barriers:
TL-1, TL-2, and TL-3 require successful tests of an 820-kg car impacting a barrier at 20 degrees, and a 2,000-kg pickup truck impacting a barrier at 25 degrees, at speeds of 50 km/h, 70 km/h, and 100 km/h, respectively.
TL-4 adds an 8,000-kg single-unit truck at 15 degrees and 80 km/h to the TL-3 matrix; TL-5 substitutes a 36,000-kg tractor/van trailer for the single-unit truck. TL-6 substitutes a 36,000-kg tractor/tank trailer.
Click on the acceptance letter number to view copies of acceptance letters, with enclosures, for each Report 350-accepted device and for synthetic guardrail blocks. A direct link is provided to the websites of many manufacturers of proprietary devices.
Research is underway (October 2007) to design a short-radius guardrail section for use at intersections that will meet the requirements of NCHRP Report 350. Until a new design becomes available, the design shown in FHWA Technical Advisory T5040.32 may be used. The text of the Technical Advisory may be found at http://www.fhwa.dot.gov/legsregs/directives/techadvs/t504032.htm and the drawings are linked here.
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