1200 New Jersey Avenue, SE 

May 29, 2009 Washington, D.C. 20590

In Reply Refer To: 

HSSD/B-192 

Mr. Robert Williams 

President, BWW Enterprises, Inc. 

5733 South Dale Mabry Highway 

Tampa, FL 33611 

Dear Mr. Williams: 

 

This letter is in response to your request for the Federal Highway Administration (FHWA) 

acceptance of a roadside safety product for use on the National Highway System (NHS). 

 Name of system: BWW Enterprises Diamond Block 

 Type of system: W-Beam Guardrail Offset Block, 8-inch 

 Test Level: NCHRP Report 350 TL-3 

 Testing conducted by: Midwest Roadside Safety Facility 

 Date of request: March 4, 2009 

 

You requested that we find this product acceptable for use on the NHS under the provisions of 

the National Cooperative Highway Research Program (NCHRP) Report 350 “Recommended 

Procedures for the Safety Performance Evaluation of Highway Features.” 

Requirements 

Roadside safety systems should meet the guidelines contained in the NCHRP Report 350. The 

FHWA Memorandum “Identifying Acceptable Highway Safety Features” of July 25, 1997, 

provides further guidance on crash testing requirements of longitudinal barriers. 

Description 

The Diamond Block is comprised of approximately 97.65 percent recycled high density 

polyethylene plastic, 1.25 percent chemical blowing agent, 1 percent carbon black, and 

0.1 percent UV stabilizer. It measures approximately 7.5 inches x 4.6 inches x 14.5 inches tall 

with a recess on the back to accommodate the face of the guardrail post. The voided design of 

the block is seen in the drawing which is enclosed for reference. The block’s weight is in the 

range of 5.8 to 5.9 pounds. 
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Crash Testing 

The Midwest Roadside Safety Facility conducted two bogie vehicle tests using standard steel 

guardrail posts held rigidly in a test foundation. One test evaluated the performance of a 

standard routed wood blockout, and the other evaluated the Diamond Block (named EXUL-1 

during the testing phase). In both cases the bogie vehicle impacted a short length of w-beam rail 

mounted on the face of the blockout. In the wood blockout test the 2190-pound bogie impacted 

the test article at 20 mph. In the test of the Diamond block the 1817-pound bogie impacted the 

test article at 23.0 mph. 

Based on the results of the crash tests, no significant differences were observed between the 

performance of the wood and plastic spacer blocks. Both blocks displayed similar levels of 

permanent damage after impact. Analysis of the high-speed video showed that the plastic block 

remained firmly attached to the post during the impact with the router gripping the front flange 

of the post until it was overridden by the bogie vehicle. No concerns were observed with regards 

to the dynamic performance nor the structural integrity of the plastic blockout when compared 

with the wood. In addition, the force vs. deflection curve for the Diamond Block test was cross 

plotted against component testing using results from two previously FHWA accepted plastic 

blockouts. The results of this comparison showed that the Diamond blockout displayed similar 

force vs. deflection behavior to previously accepted designs. 

Findings 

Therefore, the guardrail offset block described above and detailed in the enclosed drawing is 

acceptable for use on the NHS under the range of conditions tested, when such use is acceptable 

to a highway agency. 

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

• This acceptance is limited to the crashworthiness characteristics of the systems and does not 

cover their structural features, nor conformity with the Manual on Uniform Traffic Control 

Devices. 

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

new acceptance letter. 

• Should the FHWA discover that the qualification testing was flawed, that in-service 

performance reveals unacceptable safety problems, or that the system being marketed is 

significantly different from the version that was crash tested, we reserve the right to modify 

or revoke our acceptance. 

• You will be expected to supply potential users with sufficient information on design and 

installation requirements to ensure proper performance. 

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

essentially the same chemistry, mechanical properties, and geometry as the EXUL-1 that was 

crash tested for acceptance, and that w-beam guardrail using the Diamond Block will meet 

the crashworthiness requirements of the FHWA and the NCHRP Report 350. 

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

B-192 and shall not be reproduced except in full. This letter and the test documentation upon 

which it is based are public information. All such letters and documentation may be 

reviewed at our office upon request. 
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• The Diamond Block is a patented product and considered proprietary. If proprietary systems 

are specified by a highway agency for use on Federal-aid projects, except exempt, non-NHS 

projects, (a) they must be supplied through competitive bidding with equally suitable 

unpatented items; (b) the highway agency must certify that they are essential for 

synchronization with the existing highway facilities or that no equally suitable alternative 

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. 

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

use, manufacture, or sell any patented system for which the applicant is not the patent holder. 

The acceptance letter is limited to the crashworthiness characteristics of the candidate 

system, and the FHWA is neither prepared nor required to become involved in issues 

concerning patent law. Patent issues, if any, are to be resolved by the applicant. 

Sincerely, 

David A. Nicol, P.E. 

Director, Office of Safety Design 

Office of Safety 

Enclosures 

FHWA:HSSD:NArtimovich:tb:x61331:5/19/09 

File: s://directory folder/nartimovich/B192DiamondBlockFinal.doc 

cc: HSSD (Reader, HSA; Chron File, HSSD; N.Artimovich, HSSD; 

 WLongstreet, HSSD; M.McDonough, HSSD)