November 2, 2004
Refer to: HSA-10/WZ-193
Mr. Peter A. Speer
Vice President, Sales
Davidson Traffic Control Products
3110 70th Avenue, East
Tacoma, Washington 98424
Dear Mr. Speer:
Thank you for your letter of January 13, 2003, requesting Federal Highway Administration (FHWA) acceptance of your company's FG300 Curb System as a crashworthy traffic control device for use in work zones on National Highway System (NHS). Accompanying your letter was a detailed description of the product. In our initial response we requested that crash testing be conducted. On July 22, 2004, you submitted reports of crash testing conducted by the Texas Transportation Institute and video of the tests. You requested that we find these devices 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 are those lightweight devices which are to be self-certified by the vendor, Category II devices are other lightweight devices which need individual crash testing but with reduced instrumentation, Category III devices are barriers and other fixed or heavy devices also needing crash testing with normal instrumentation, and Category IV devices are trailer mounted lighted signs, arrow panels, etc. for which crash testing requirements have not yet been established. 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.
A brief description of the devices follows:
The Davidson Traffic Control Products FG300 Curb System consists of plastic curb sections alternating with circular delineator bases, all of which are attached to the pavement. The curb sections measure 7 ¾ inches wide at the base by 2 inches tall by approximately 30 ¾ inches long.
The curb sections are anchored with six steel bolts capable of holding 5,000 pounds in tension and are connected by round plastic base pieces to form a continuous longitudinal appearance. The "T" shaped plastic delineators are 3 inches by 2 inches by 36 ½ inches. The delineators are inserted into the 8 inch diameter base pieces which are anchored by four bolts, with the flat side of the delineator facing traffic. The delineators are held into the bases by two plastic pins.
|FG 300 HD Base||Thermoplastic||8 in dia. x 2 in tall||1.6 pounds|
|FG336 UR Post||Urethane Plastic||3 in dia. x 36 in tall||1.7 pounds|
|FG300 Curb Unit||Thermoplastics||8 in wide x 2 in tall x 32 in long||3.5 pounds|
|Bolts||Tempered Steel||Either 2.5 in or 4 in long||2 oz|
|Refl. Road Studs||Thermoplastic & Glass||2 in x 1 in x 0.5 in tall||0.1 oz|
Full-scale automobile testing was conducted on your company' devices. As longitudinal channelizing curbs are not intended to redirect vehicles, nor are the plastic delineator posts likely to damage the windshield of a test vehicle, no standard crash test found in the NCHRP Report 350 is appropriate. Therefore, a special test matrix was recommended by the FHWA. A fourth test, similar to one conducted by a competitor, was run in addition to the three recommended tests.
Test 1. Traversal of the curb at 20 degrees. An installation of the FG300 system measuring 55 ft, 6 inches long included 19 delineators at 36.5 inch spacing on centers. The live-driver test vehicle impacted the curb system near delineator #8 at an angle of 20 degrees and a speed of 64.8 mph. The final delineator contacted was #13. The vehicle sustained dimpling of the hood and a dislodged driver's side mirror. The vehicle did not vault.
Test 2. Traversal of the curb at 0 degrees. Total length of the FG300 system was 101 ft, 1 inch. No delineators were installed in the curb system for this test. The vehicle impacted the curb at 61.4 mph, and rode up onto and along the curb. The left front and rear tires remained on the curb for the entire length of the installation . No damage to the vehicle occurred and there was no vaulting.
Test 3. Lane Change Maneuver. Total length of the system was 101 ft, 1 inch. No delineators were installed for this test. The test vehicle was traveling at 60.8 mph, with the first tire contact at the 54 foot mark. The final tire crossed over at 83 ft 6 inches. There was no damage to the vehicle and no vaulting occurred.
Test 4. Traversal of "Vee" at zero degrees. In this test, a "vee" of curb channelizers were installed as if they were shielding a crash cushion or gore hazard. On one side the 101 foot, 1 inch installation was re-used, and an additional 31 ft, 1 ¾ inch section was placed on the left side of the "vee." No delineators were used in this test. The test vehicle contacted the apex of the channelizers head-on and maintained the straight-ahead position with minimal steering input. As in the other three tests, the vehicle's tires rode over the curb units and became momentarily airborne. The vehicle did not rise up on its suspension, rather it maintained a level trajectory.Findings
Damage was limited to the hood dimpling and mirror damage noted in the first test. None of the curb segments became dislodged during any of the tests, and there was no potential for windshield damage or passenger compartment intrusion. In each test the vehicle's tires left the pavement as they traversed the 2 inch high curb, but returned to the ground approximately one foot later.
The results of the testing met the FHWA requirements and, therefore, the devices described in the various requests above and detailed in the enclosed drawings are acceptable for use on the NHS under the range of conditions tested, when proposed by a State.
Please note the following standard provisions that apply to the FHWA letters of acceptance:
/Original Signed by/
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety