Refer to: HSA-10/WZ-147

Mr. Geoff Grzywinski
Reflexite Americas
315 South Street
New Britain, Connecticut  06051

Dear Mr. Grzywinski

This is in response to your letters of December 20, 2002, and January 9, 2003, requesting Federal Highway Administration (FHWA) acceptance of your company's 10 mm thick Endurance® sign substrate material for use on crashworthy traffic control devices in work zones on the National Highway System (NHS).  Accompanying your letter was a comparison of the Reflexite Endurance 10 mm material with other sign substrates.  You requested that we find 10 mm Endurance 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.” Specifically, you requested that 10 mm Endurance be accepted wherever the following substrates have been previously tested and/or accepted for use:

Reflexite Americas Endurance 16 mm
Stabler Industries 5/8 injection molded high density polyethelene
Various 10mm corrugated plastics, including IntePro, CoroPlast, and SafetyCor
Aluminum / Plastic composites, including Alpolic, Renalite, and Aluswiss


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.

Most crash testing of portable sign stands was for specific combinations of sign substrate and stand. Early testing focused on roll-up signs on X-footprint sign stands. Recent testing has looked at rigid substrates and the “worst case scenario” tests.  The testing has included the most critical combination(s) of stand and sign.  FHWA has accepted a range of substrates on various manufacturers' stands by observing tests that “bracketed” the materials that the stand could be expected to support.


Comparison to 16 mm Endurance

Full scale crash testing was conducted on 16 mm Endurance signs by Reflexite using Dicke Tool sign stands.  These devices were found acceptable via FHWA Acceptance Letter WZ-52 dated September 21, 2000.  Because the 16 mm Endurance substrate can be considered a “worst case scenario” when comparing it to 10 mm Endurance, the lighter substrates will be acceptable for use on any stand successfully tested with the16 mm material.

Comparison to 10 mm polypropylene

Various manufacturers' 10 mm thick polypropylene substrates have been tested on a number of different stands that have received FHWA letters of acceptance, namely:

WZ-23 dated October 26, 1999,
WZ-46 dated July 21, 2000,
WZ-74 dated March 15, 2001,
WZ-78A dated June 15, 2001
WZ-103A dated March 6, 2002

The 10 mm Endurance substrate is fabricated from the same high performance thermoplastic material as 16 mm Endurance, but in the same structure (cell wall thickness, spacing of ribs, etc.) as the 10 mm polypropylene substrates.  Your in-house bending tests show that its static behavior is similar to that of 0.080 solid aluminum, though it is approximately half the weight.  Those flexibility tests showed the 10 mm Endurance was stiffer than the polypropylene substrates, however their mass and construction is very similar (less than a 10 percent difference in weight.)  We believe that the difference in real-world performance between these 10 mm plastics will not likely be observable.


We concur in your request that 10 mm Endurance sign panels will be acceptable on sign stands successfully crash tested with heavier / stiffer substrates such as

Reflexite Americas Endurance 16 mm
Stabler Industries 5/8 injection molded hdpe
Aluminum / Plastic composites, including Alpolic, Renalite, and Aluswiss

It will also be considered acceptable on sign stands successfully crash tested with the other 10 mm corrugated plastic substrates such as

IntePro, CoroPlast, and SafetyCor

This action does not make all lightweight substrates interchangeable on all sign stands. Although 10 mm Reflexite may be used on stands tested with other 10 mm corrugated plastics, the 16 mm Reflexite (and similar heavier, stiffer substrates) may not.  The 10 mm Reflexite can be used on stands were the heavier stiffer substrates listed above are acceptable.

As discussed above 10 mm Reflexite sign substrate material is acceptable for use on the NHS under the range of conditions specified, when proposed by a State.

Please note the following standard provisions that apply to FHWA letters of acceptance:

Sincerely yours,

Michael S. Griffith
Acting Director, Office of Safety Design
Office of Safety