Refer to: HSA-10/WZ-152
Mr. Chuck Mettler
Plastic Safety systems
2444 Baldwin Road
Cleveland, Ohio 44104
Dear Mr. Mettler:
This is in response to your letter of March 24, 2003, requesting Federal Highway Administration (FHWA) acceptance of a modification to your company's Type III barricades as crashworthy traffic control devices for use in work zones on the National Highway System (NHS). Plastic Safety System's Type III Barricades were found acceptable in our letter, WZ-61, dated December 13, 2000. You requested that we find these barricades, when using a new skid design, acceptable for use on the NHS under the provisions of National Cooperative Highway Research Program (NCHRP) Report 350 "Recommended Procedures for the Safety Performance Evaluation of Highway Features."
The FHWA guidance on crash testing of work zone traffic control devices is contained in two memoranda. The first, dated July 25, 1997, titled "INFORMATION: Identifying Acceptable Highway Safety Features," established four categories of work zone devices: Category I devices were those lightweight devices which could be self-certified by the vendor, Category II devices were other lightweight devices which needed individual crash testing, Category III devices were barriers and other fixed or massive devices also needing crash testing, and Category IV devices were trailer mounted lighted signs, arrow panels, etc. The second guidance memorandum was issued on August 28, 1998, and is titled "INFORMATION: Crash Tested Work Zone Traffic Control Devices." This later memorandum lists devices that are acceptable under Categories I, II, and III.
Description of the barricade as initially accepted follows:
The horizontal rails, or "legs," are 1217-mm long, 98 mm square HDPE, and are placed 1225 mm apart. Underneath each end of the legs rubber pads are attached to increase friction with the pavement. On the top center of each leg is bolted a 127 mm x 76 mm steel plate, to which is welded a 72 mm diameter x 3.06 mm wall x 200 mm long steel tube. These steel tubes support the vertical upright masts, which are 88 mm square x 5.08 mm wall x 1521 mm long High Density Polyethelene (HDPE) plastic. To these vertical masts are bolted (with 1/4 - 20 bolts and nuts with washers) three 205 mm wide x 22.75 mm thick x 2435 mm long HDPE honeycomb extrusions. A "ballast board" was also used to connect the legs. This 130 mm wide x 29.83 mm thick x 1225 mm long HDPE extrusion with a wall thickness of 6.1 mm was installed as a safer location to place sandbags.
Full-scale automobile testing was conducted on your company's original devices. Two stand-alone examples of each were tested in tandem, one head-on and the next placed six meters downstream turned at 90 degrees, as called for in our guidance memoranda. Damage was limited to slight to moderate cracking of the windshield and superficial damage (scrapes) to the bumper, hood, quarterpanel, and doors, and was documented in WZ-61.
You requested that the "ANCHOR" base system, shown in the enclosed drawing for reference, be used in lieu of the square HDPE skids used on the tested system. Because we know that the barricade frame and panels remain together during crash testing, the unknown factor in the performance was the ability of the barricade to separate from the "ANCHOR" base system. You performed informal crash testing with an automobile on a Type III barricade using two ANCHOR bases to support the upper portion of a barricade that was identical to that tested and accepted in WZ-61. Each base was ballasted with 45 pounds of sand, giving a total weight of 50 pounds per side.
The barricade frame and panels separated cleanly from the ANCHOR base and were knocked ahead of the vehicle, showing no tendency to contact the windshield. Because these tests showed that the performance of the Plastic Safety Systems Type III Barricade was as good, if not better, using the ANCHOR base we concur that the Plastic Safety Systems Type III Barricade described above and shown in the enclosed drawings for reference are acceptable for use as Test Level 3 devices on the NHS under the range of conditions tested, when proposed by a State.
Please note the following standard provisions that apply to FHWA letters of acceptance:
Michael S. Griffith
Acting Director, Office of Safety Design
Office of Safety