March 17, 2004 

Refer to: HSA-10/B-109B 

Mr. Michael J. Burkett

Burkett Moulding, Incorporated

21 Hamilton Street 

Monroeville, Ohio 44847 

Dear Mr. Burkett: 

A recycled plastic offset block (called the P-Block) for use with strong steel post W-beam 

guardrail was accepted for use on National Highway System (NHS) on November 7, 2002, 

(Federal Highway Administration ((FHWA)) acceptance letter B-109). A similar design for use 

with round wood posts was accepted on August 29, 2003 (acceptance letter B-109A). Both 

letters were addressed to Mr. Daniel J. Mushett with Interstate Timber Products Company. 

In your March 9, 2004, letter to Mr. Richard Powers of my staff, you advised him that you have 

purchased the rights to the P-Block from Interstate Timbers Products Company and have further 

modified its design. You indicated that your modified block is comprised of the same materials 

as the P-Block (approximately 50/50 blend of High Density Polyethylene and Low Density 

Polyethylene with a small amount of additives), but that the flared “wings” centered along the 

back edge of the block have been lengthened from their original 7 inches to 12 inches. The 

traffic face of the block remains approximately 4-inches wide and its effective depth remains at 

just under 8 inches. These details are shown on the enclosed drawing (Enclosure 1). You had 

this redesigned block crash tested at E-TECH Testing Services, Inc. in Rocklin, California, the 

results of which are contained in that agency’s March 2003 report entitled “NCHRP Report 350 

Crash Test Results for the Burkett Molding P-Block Guardrail Blockout.” Enclosure 2 is the 

summary page from the report that shows the 2000P pickup truck was fully contained and 

smoothly redirected following an impact into a strong post W-beam guardrail installation in 

which the modified P-Block was used in lieu of standard routed timber blockouts. 

I agree that the modified P-Block, as described above, is acceptable for use with strong post 

W-beam guardrail installations on the NHS. Minor modifications to the dimensions of the 

P-Block for use with Thrie-beam guardrail (longer block and wings) and with round wood posts 

(concave backside to match the posts) are also acceptable. 
2

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

• This acceptance is limited to the crashworthiness characteristics of the offset block and 

does not cover its long-term durability. 

• Any changes that may adversely influence the crashworthiness of the device will require 

a new acceptance letter.

• Should the FHWA discover that in-service performance reveals unacceptable safety 

problems, or that the device being marketed is significantly different from the version 

that was accepted, it reserves the right to modify or revoke its acceptance.

• You will be expected to certify to potential users that the blocks furnished have 

essentially the same chemical composition and geometry as that submitted for 

acceptance. 

• To prevent misunderstanding by others, this letter of acceptance, designated as number 

B-109B shall not be reproduced except in full. This letter, and the documentation upon 

which this letter is based, is public information. All such letters and documentation may 

be reviewed at our office upon request. 

• This acceptance letter shall not be construed as authorization or consent by the FHWA to 

use, manufacture, or sell any patented device for which the applicant is not the patent 

owner. The FHWA acceptance is limited to the crashworthiness characteristics of the 

candidate device, and this office is neither prepared nor required to resolve issues 

concerning patent law. Please note that the FHWA reserves the right to withdraw an 

acceptance letter if the applicant’s submission is later shown to misrepresent the issue, 

either intentionally or unintentionally, or contains errors of fact or omission. 

• If your product is patented, it cannot be specified for use on Federal-aid projects, except 

exempt, non-NHS projects. Our regulations concerning proprietary products are 

contained in Title 23, Code of Federal Regulations, Section 635.411, a copy of which is 

Enclosure 3. 

Sincerely yours, 

 

 (original signed by Hari Kalla) 

 for: 

 John R. Baxter 

 Director, Office of Safety Design 

 Office of Safety 

3 Enclosures 

 P-Block Blockout Crash Test Results - 9 of 34

E-TECH Testing Services, Inc.

Figure 1. Summary of Results - P-Block Blockout NCHRP 350 Test 3-11

t = 0.000 sec t = 0.120 sec t = 0.240 sec t = 0.360 sec t = 0.480 sec t = 0.600 sec

General Information

Test Agency ............................................................. E-TECH Testing Services, Inc.Test Designation ...................................................... NCHRP 350 Test 3-11Test No. ................................................................... 53-0017-001Date .......................................................................... 12/17/03

Test Article

Type ......................................................................... Burkett Moulding, Inc.

.......................................................................... P-Block Guardrail Blockout

Installation Length ................................................ 53.34 m Guardrail (overall)Material and key elements ..................................... AASHTO SGR04a Guardrail with

.......................................................................... SEW02a End Terminal equipped.......................................................................... with 152 mm x 203 mm x 354 mm.......................................................................... 3.2 kg blockouts of a 50-50 mix of.......................................................................... LDPE/HDPE regrind plastic

Foundation Type and Condition .................................. NCHRP 350 Strong Soil, well

.......................................................................... drained

Test Vehicle

Type ......................................................................... Production ModelDesignation .............................................................. 2000PModel ....................................................................... 1989 Chevrolet C2500

.......................................................................... 3/4 Ton Pickup

Mass (kg)

Curb ................................................................. 1972Test inertial .................................................... 1995

Impact Conditions

Speed (km/h) ........................................................... 99.7Angle (deg) .............................................................. 25Impact Severity (kJ) ............................................... 136.6

Exit conditions

Speed (km/h) ........................................................... 50.8Angle (deg - veh. c.g.) ............................................. 12

Occupant Risk Values

Impact Velocity (m/s)

x-direction ....................................................... 5.0y-direction ....................................................... -4.5

Ridedown Acceleration (g's)

x-direction ....................................................... -8.4y-direction ....................................................... -8.9

European Committee for Normalization (CEN) Values

THIV (km/h) ............................................................ 23.9PHD (g's) ................................................................. 11.3ASI .......................................................................... 0.7

Post-Impact Vehicular Behavior (deg - rate gyro)

Maximum Roll Angle ............................................ -4.0Maximum Pitch Angle ........................................... -7.0Maximum Yaw Angle ............................................ -43.5

Test Article Deflections (m)

Dynamic .................................................................. 0.9Permanent ............................................................... 0.6

Vehicle Damage (Primary Impact)

Exterior

VDS .................................................................. RFQ-3CDC ................................................................. 01RFEW3

Interior

VCDI ................................................................ AS0000000Maximum Deformation (mm) ........................ Negligible
Sec. 635.411 Material or product selection. 

(a) Federal funds shall not participate, directly or indirectly, in payment for any premium or royalty on any 

patented or proprietary material, specification, or process specifically set forth in the plans and 

specifications for a project, unless: 

(1) Such patented or proprietary item is purchased or obtained through competitive bidding with equally 

suitable unpatented items; or 

(2) The State highway agency certifies either that such patented or proprietary item is essential for 

synchronization with existing highway facilities, or that no equally suitable alternate exists; or 

(3) Such patented or proprietary item is used for research or for a distinctive type of construction on 

relatively short sections of road for experimental purposes. 

(b) When there is available for purchase more than one nonpatented, nonproprietary material, semifinished 

or finished article or product that will fulfill the requirements for an item of work of a project and these 

available materials or products are judged to be of satisfactory quality and equally acceptable on the basis 

of engineering analysis and the anticipated prices for the related item(s) of work are estimated to be 

approximately the same, the PS&E for the project shall either contain or include by reference the 

specifications for each such material or product that is considered acceptable for incorporation in the work. 

If the State highway agency wishes to substitute some other acceptable material or product for the material 

or product designated by the successful bidder or bid as the lowest alternate, and such substitution results in 

an increase in costs, there will not be Federal-aid participation in any increase in costs. 

(c) A State highway agency may require a specific material or product when there are other acceptable 

materials and products, when such specific choice is approved by the Division Administrator as being in 

the public interest. When the Division Administrator's approval is not obtained, the item will be 

nonparticipating unless bidding procedures are used that establish the unit price of each acceptable 

alternative. In this case Federal-aid participation will be based on the lowest price so established. 

(d) Appendix A sets forth the FHWA requirements regarding (1) the specification of alternative types of 

culvert pipes, and (2) the number and types of such alternatives which must be set forth in the 

specifications for various types of drainage installations. 

(e) Reference in specifications and on plans to single trade name materials will not be approved on 

Federal-aid contracts.