U.S. Department 

Of Transportation 

Federal Highway 

Administration

400 Seventh St., S.W. 

Washington, D.C. 20590 

July 14, 1986 

Refer to: HNG-21/SS-01A 

Mr. H. Mike Jordan 

Product Manager 

Southwestern Pipe, Inc. 

P.O. Box 2002 

Houston, Texas 77252-2002 

Dear Mr. Jordan: 

This is in response to your June 9 letter requesting Federal Highway Administration 

(FHWA) acceptance of two-post installations of certain sizes of your company’s Type 

“A” Small Sign Support System for use on Federal-aid highway projects. You enclosed a 

copy of a POZ-LOC Anchor System brochure and a Southwest Research Institute Report 

No. 06-1120-001 dated May 1986 containing full-scale crash test information. 

Our May 13 letter provided acceptances on your 2 3/8-inch O.D. 13 gauge (.095), 14 

gauge (.030) and 16 gauge (.065) signposts. We limited our acceptance then to only one 

post per 8-foot path. 

You have now conducted an additional test of the 2 3/8-inch O.D. 13 gauge (.095) sign 

post where two posts were impacted. The tested system consisted of separate 2 7/8-inch 

O.D. by .109 galvanized tubular sockets that were driven into soil meeting the National 

Cooperative Highway Research Program (NCHRP) Report No. 230 strong soil (S01) 

criteria. Separate 2 3/8-inch O.D. 13 gauge signposts were inserted into the sockets and 

the posts locked into position with 2 7/8-inch by 2 3/8-inch x 11 gauge post wedges. 

Enclosed is a figure showing the sign support details. The full-scale test was conducted 

with a 1,850-pound vehicle impacting the two-post installation at 20.6 m.p.h. Reported 

test results, using the average of the film and accelerometer data, indicate a change of 

velocity of 14.8 feet/second. These translate to a change of momentum of 859 

pound/seconds. Also, we concur with your assessment that the two-post installation is 

acceptable under high speed (60 m.p.h.) impacts based on previous testing. Therefore, 

the tested system meets the provisions of the new, but yet unpublished, 1985 American 

Association of State Highway and Transportation Officials (AASHTO) “Standard 

Specifications for Structural Supports for Highway Signs, Luminaires and Traffic 

Signals”. We also infer this system meets the 1975 AASHTO specification since the 

1985 AASHTO specification is more demanding. 
Based on the above, your tested system is acceptable for use on Federal-aid projects if 

proposed by a State. Also, we infer that your POZ-LOC anchor systems comprised of 

the same socket, wedge, and post O.D. as the tested system, only the posts have thinner 

wall thicknesses of .080 and .065, are also acceptable when two posts are used within an 

8-foot path. 

We note your system was only tested in the S-1 strong soil described in NCHRP Report 

No. 230. If you desire to use this system in soil equivalent to the S-2 soil described in 

NCHRP Report No. 230, we recommend additional tests be conducted in that soil type. 

At the present time, FHWA has not yet adopted the 1985 AASHTO specification. Once 

the AASHTO publishes their specification, we intend to proceed with the process to 

officially adopt a new specification. We will issue a Notice of Proposed Rulemaking 

(NPRM) in the Federal Register, provide a public comment period, review and evaluate 

any comments we receive, and then issue a Final Rule. The effective date of 

implementing a new specification for Federal-aid highway work is not expected to be 

until at least mid 1987. 

This acceptance is limited to breakaway characteristics of the system described above and 

does not cover its structural features. Presumably, Southwestern Pipe, Inc., will supply 

potential users with sufficient information on structural design and installation 

requirements, including the need to size the sign panel and support for expected wind 

loading, to ensure proper support performance. 

We anticipate that the States will require certification from Southwestern Pipe, Inc., that 

materials furnished have essentially the same chemistry, mechanical properties, and 

geometry as the materials used in the tests and that the support will meet the change in 

momentum requirements of the AASHTO specification. 

 Sincerely yours, 

 Norman J. Van Ness, Chief 

 Highway Design Division 

Enclosure