July 11, 2002
Sidney D. Chase
Armorcast Products Company
13230 Saticay Street
North Hollywood, California 91605
Dear Ms. Chase:
Dr. Dean Alberson's June 11 letter to Mr. Richard Powers of my staff requested Federal Highway Administration acceptance of a modified "350 kit" for use with the Guardian Barrier. This modification eliminates the steel straps used to support the 2-inch diameter Schedule 40 steel pipes and attach them to the sides of the barrier. Instead, these pipes are now bolted together through the plastic barrier using ½-inch diameter threaded rods. In addition, rubber spacers are used to extend the upper pipe rails beyond the face of the barrier, placing them approximately over the lower pipe rails, which have been recessed into the barrier. The connection of the pipe rails at the joints is identical to the previously accepted design, as are the overall dimensions of the plastic barrier segments. Details of the modified design are shown as an enclosure to this letter.
Because the only significant difference from the original Guardian is the method of attaching the 350 kit to the barrier, the modified design can be considered equivalent and the Guardian barrier may be used on the National Highway System (NHS) as an NCHRP Report 350 test level 3 (TL-3) traffic barrier. However, since the new attachment detail has not been crash tested, I recommend that an informal in-service evaluation be conducted to verify satisfactory field performance. Chapter 7 of NCHRP Report 350 outlines the requirements for an appropriate in-service evaluation of roadside hardware.
The Guardian Barrier is a patented device and is thus considered proprietary. The use of proprietary work zone traffic control devices in Federal-aid projects is generally of a temporary nature. They are selected by the contractor for use as needed and removed upon completion of the project. Under such conditions they can be presumed to meet requirement (a) below for the use of proprietary products on Federal-aid projects. On the other hand, if proprietary devices are specified for use on Federal-aid projects, except exempt, non-NHS projects, they: (a) must be supplied through competitive bidding with equally suitable unpatented items; (b) the highway agency must certify that they are essential for synchronization with existing highway facilities or that no equally suitable alternative exists or; (c) they must be used for research or for a distinctive type of construction on relatively short sections of road for experimental purposes. Our regulations concerning proprietary products are contained in Title 23, Code of Federal Regulations, Section 635.411, a copy of which is enclosed.
Should you have any questions concerning this letter, please call Mr. Powers at (202) 366-1320.
(original signed by Harry W. Taylor)
Carol H. Jacoby, P.E.
Director, Office of Safety Design