Q

US.Department 400 Seventh St, S.W

of Transportation Washington, D.C. 20590

Federal Highway

Administration SEP | (992 Refer to: HNG-14

Mr. Robert A. Seavey
Business Development Manager
Composite Products Division
P.0. Box 5445

Norwalk, Connecticut 06856

Dear Mr. Seavey:

Thank you for your letter of August 12 to Mr. Thomas 0. Willett requesting the
Federal Highway Administration's (FHWA) acceptance of "Timbrex" composite
material guardrail blockouts. Timbrex is made from recycled plastic and
sawdust using equipment and technology acquired from the Rivenite Corporation.
You enclosed two reports in support of your request. The first, dated August
1992, by Charles F. McDevitt of the FHWA and Piyush K. Dutta of the U.S. Army
Cold Regions Research Laboratory, describes static tests of the material and a
full scale crash test of w-beam guardrail using Timbrex recycled plastic
lumber blockouts and posts. The second, dated June 1992, by Joe B. Meyer of
the Southwest Research Institute (SWRI), describes a full scale crash test of
a modified G4(2W) wood post w-beam with Timbrex blockouts. The blockouts
measured 152-mm x 203-mm x 355-mm (6 inches x 8 inches x 14 inches) in both
tests.

The test results are summarized here:

Guardrail Type W-beam w/recycled G4(2W)modified w/recycled
plastic posts and blockouts plastic blockouts

Vehicle Mass, kg 816 (1,800) 2009 (4430)

(wt, Tbs) .

Impact Speed, km/h 95.7 (59.5) 91.2 (56.7)

(mph)

Angle, degrees 20 25.7

Occupant Impact Velocity, m/s (fps) (average of film and accelerometer data)
Forward 6.1 (20.1) 5.2 (17.0)
Lateral 5.1 (16.6) 4.5 (14.7)


Occupant Ridedown Acceleration (g's)

Forward 3.1 4.8
Lateral 9.7 8.4
Maximum Rail 609 (24) 1100 (43)

Deflection, mm (in)

The results meet the velocity, acceleration, and post-impact trajectory
requirements of National Cooperative Highway Research Program Report 230.
Therefore, 152-mm x 203-mm (6-inch x 8-inch) Timbrex blockouts as a one-for-
one substitute for wood blockouts on G4(2W) guardrail are acceptable for use
on Federal-aid projects, within the range of conditions tested, if proposed by
a State.

You also requested acceptance for Timbrex block-outs on w-beam strong steel
post guardrail, designed G4(2S). We believe recycled plastic lumber blockouts
will probably work satisfactorily in "C" post and wide-flange steel-post
guardrail systems. However, we believe this needs to be confirmed through
crash tests. Therefore, Timbrex blockouts are not acceptable for use on steel
post guardrail systems, including the G4(2S), without further crash testing.

The small car test shows that Timbrex posts are not an acceptable one-for-one
substitute for standard wood posts in the G4(2W) barrier since the rail
deflection was more than twice what is normally expected under similar test
conditions. We recognize that you did not request our acceptance of this
substitution. However, since it was covered in the information you submitted
we believed we needed to make our position clear. On the other hand, we would
consider a new, fully tested guardrail system incorporating Timbrex posts if
one is developed. In fact, the design you tested might meet the acceptance
requirements, albeit with greater deflection than the G4(2W) system, if fully
tested.

From the static testing, we note that there were quality problems with the
Timbrex material until the manufacturing process was changed to more carefully
control sawdust size. Lacking a material specification, Mobil Chemical should
certify that the materials supplied are at least as good as those tested. We
would suggest that you work with the States towards developing a material
specification to ensure product quality.

Timbrex is a proprietary material. Thus, to be used in a Federal-aid project
Timbrex blockouts: (a) must be supplied through competitive bidding with
equally suitable unpatented items; (b) the highway agency must certify that
they are essential for synchronization with existing highway facilities or


that no equally suitable alternate exists; or (c) they must be used for
research or for a distinctive type of construction on relatively short
sections of road for experimental purposes. Our regulations concerning
proprietary products are contained in Title 23, Code of Federal Regulations,
Section 635.411 a copy of which is enclosed.

Sincerely yours,

LG. Mam

Lawrence A. Staron
Chief, Federal-Aid and Design Division
Enclosure

Federal Highway Administration
HNG-14:NArt imov ich: gm:8-28-92 :6133]
copies to:

HPD-1 HNG-1 HNG-10 HNG-14 Reader, 3
Reader, 3206 Reader, 3128 File 3138

LETTER TO MOBIL CHEMICAL COMPANY

GEOMETRIC AND ROADSIDE DESIGN ACCEPTANCE LETTER NUMBER B-20