Street pole performance and acceptance for safety...

We have had folks asking if we provide a break-away system for street poles…

Although we officially do not provide a break-away system, what we have found is that the alloy we use for our aluminum poles is often considered a valid option.

In researching the subject here is some of the information we have found:

  

1. Department of Transportation State of North Carolina 1/26/2006

Subject: NCHRP 350 Compliance of Metalcraft 3” outer Diameter 1/8” wall thickness, Alloy 6061-T6 Aluminum Tube Signs Supports

The signing section has reviewed the subject product and found that it will provide adequate breakaway performance.

FHWA acceptance letter SS-15 documents Texas Transportation Institute testing that indicates a thin-walled aluminum tube smaller than 4” in diameter will provide adequate breakaway performance in strong soils…

 A copy in full of this letter (SS-15) can be found here-

This letter does not infer that this product will or must be used by Department forces…

A follow up acceptance letter (SS 35) notes 3" & 4" w/ wall thicknesses of 0.125" can be found here-

2. U.S. Department of Transportation 8/11/2011 Federal Highway Administration

Roadside safety devices should meet the guidelines contained in the National Cooperative Highway Research Program (NCHRP) Report 350 if tested prior to December 31, 2010, and the American Association of State Highway and Transportation Officials’ (AASHTO) Manual for Assessing Safety Hardware (MASH) if tested after that date.  Requirements for breakaway supports are contained in both of these documents and in AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaries, and Traffic Signals.

Decision

The following system was found acceptable, with details provided below:

Generic Aluminum support Pole 4-inch diameter with a 0.125 wall thickness

Findings

As noted in previous requests , the FHWA has previously accepted a 6061-T6 aluminum pole in 3” as well as 4” diameter poles of the same aluminum  alloy with a wall thickness of 0.125 …Therefore, the 6061-t6 aluminum pole with 4-inch outside diameter and a 0.125 inch wall thickness remains acceptable for use on NHS under the range of conditions originally tested, when such use is acceptable to a highway agency.

A copy in full of this letter (SS-173) can be found here-

Upon request, Metalcraft can send along a Letter of Certification with your order when you request our Aluminum alloy 6061-T6 poles for your sign project.