Federal Highway Administration |
400 Seventh St., S.W. Washington, D.C. 20590 |
October 13, 2005
Refer to: HSA-10/WZ-213
Mr. Paul Wander
Dicke Tool Company
1201 Warren Avenue
P.O. Box 518
Downers Grove, Illinois 60515
Dear Mr. Wander:
Thank you for your letters of April 29, May 16, and June 23, 2005, requesting Federal Highway Administration (FHWA) acceptance of a number of your company's Portable Sign Stands for roll up signs as crashworthy traffic control devices for use in work zones on the National Highway System (NHS). Accompanying your letter were detailed drawings of each of the stand variations, including the DSB100, DSB100HD, DL1003-Latch, TF1214, TF1230, DL1008, and the DL1008FT (Flag Tree). 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" by virtue of their similarity to other crash tested compact sign stands.
Introduction
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:
This family of compact sign stands support 48 x 48 roll-up signs with fiberglass spreaders on either recycled rubber bases or X-footprint stands are summarized in the following table and illustrated in the enclosed drawings for reference.
Stand |
Base |
Latch / Height |
Vertical Mast* |
Horiz Spreader* |
---|---|---|---|---|
DSB100 |
Crumb Rubber 42.0 pounds |
Bone Safety Signs latch |
1/4” thick 1 ¼” wide |
3/16” thick 1 ¼” wide |
DSB100HD |
Crumb Rubber 48.0 pounds |
Bone Safety Signs latch |
1/4” thick 1 ¼” wide |
3/16” thick 1 ¼” wide |
DL1003-Latch |
Steel, with Al. legs 1” and 1.25” |
Bone Safety Signs latch |
1/4” thick 1 ¼” wide |
3/16” thick 1 ¼” wide |
TF1214 |
Steel, dual upright springs, Al. legs 1.25” and 1.50” |
Sign attaches to mast @ 12” |
Aluminum telescoping 1.5” and 1.25” |
(none) |
TF1230 |
Steel, dual upright springs, Al. legs 1.25” |
Sign attaches to mast @ 12” |
Aluminum telescoping 1.5”, 1.25”, 1.00” |
(none) |
DL1008 |
Steel, with Al. legs 1.25” |
Sign attaches to mast @ 36” |
Aluminum telescoping 1.5”, 1.25”, 1.00” |
(none) |
DL1008FT |
Steel, with Al. legs 1.25” |
No sign. Two flags at 54.5” and two at 103” |
Aluminum telescoping 1.5”, 1.25”, 1.00” |
(none) |
* The dimensions of the horizontal and vertical fiberglass spreaders are given for the "compact" sign stands that have no mast higher than that needed to hold the bottom of the sign at the specified height. The specifications for the rollup signs and spreaders are similar for the other stands that include a metal mast that supports flags at the top of the sign.
Testing
The "compact" sign stands DSB-1000, DL-1003, and DL-1003 Latch has not been subjected to full scale crash testing. However the sign and x-footprint components are identical to others you have crash tested, and the rubber bases are similar to those that have proven to be crashworthy through crash testing and use in the field. You also conducted bogie vehicle testing to verify acceptable performance. The three stands are considered "compact sign stands" as discussed in the FHWA acceptance letter WZ-85 when supporting the roll-up signs noted above.
The TF1214 and TF1230 stands are similar in design with the TF1214 having a two-stage mast rather than the three-stage mast found in the TF1230. They are both similar in construction to the PS-3330-S that was found acceptable in the FHWA acceptance letter WZ-17 (System 12) dated June 4, 1999. Bogie testing confirmed similar performance.
The DL1008 and DL1008-FT are similar to other acceptable aluminum mast sign stands and were subjected to bogie testing. It was evident that only minor windshield contact from the roll up sign and the horizontal spreaders would result from a full-scale test. No portion of the stand itself impacted near the windshield.
Findings
The results of the bogie testing indicated that the stands detailed above would meet the FHWA requirements and, therefore, the devices described in the various requests above and illustrated 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:
Sincerely yours,
/original signed by/
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety
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