February 1, 2002 

HSA-10/B-95 

 

 

Mr. Rodney A. Boyd 

President, Highway Safety Products Group

Trinity Industries, Inc.

Post Office Box 568887

Dallas, Texas 75356-8887

Dear Mr. Boyd:

In his January 14 letter to Mr. Richard Powers of my staff, Mr. Don Johnson 

requested formal Federal Highway Administration acceptance of a new guardrail 

post (called the O-Post) as an alternative to a standard W150 x 13 steel post for use 

with w-beam guardrail and asked that our response be sent to you. To support his 

request, he also provided a copy of a Southwest Research Institute test report dated 

January 2002, entitled “Full-Scale Crash Evaluation of a 12-Gauge W-Beam G4-1S 

Guardrail System with O-Posts Used as Line Posts” and copies of the crash test 

videotape. 

The test installation was a modified strong steel post w-beam guardrail 53.3-m long. 

The modification was the substitution of your new O-Post for the standard W150 x 

12.6 support posts in the impact area (post numbers 12 through 18). Routed timber 

offset blocks measuring 140 mm x 195 mm x 360 mm were used on all posts. The OPosts were made from AASHTO M-180 12-gauge steel formed into a fluted C-shape 

with rolled edges as shown on the enclosure. All posts were 1830-mm long and were 

installed on 1900-mm centers. The height above ground to the center of the rail was 

550 mm. 

The installation was tested with a 2000-kg pickup truck impacting at 96.8 km/h and 

at an impact angle of 25.8 degrees. As noted in the test summary sheet, the test 

vehicle was contained and redirected upright. Maximum occupant impact velocity 

was reported to be 4.5 m/s and the subsequent ridedown acceleration was 12.6 g’s, 

both values being below the preferred limits of 9 m/s and 15 g’s, respectively. The 

vehicle roll angle was 11.9 degrees. The dynamic deflection of the barrier system 

was 1030 mm. We agree with the researchers’ contention that the Report 350 

occupant severity test with the 820-kg car may be waived in light of the barrier’s 

performance with the pickup truck. The reported deflection was very similar to the 

deflection noted in the Texas Transportation Institute test 3-11 of the standard 

strong steel post w-beam with wood offset blocks.

Based on the information you provided, I agree that the O-Post may be considered 

acceptable for use on the National Highway System as a substitute for the standard 

steel post currently used in the modified G4(1S) barrier system when such use is 

requested by the contracting highway agency. It must be used with a wood or 
plastic offset block and oriented as tested with the open side of the post facing the 

downstream end of the barrier installation. Please note that this acceptance is only 

for the use of these posts in the barrier proper. They cannot be used in any of the 

guardrail terminals that require weakened or breakaway posts unless specifically 

tested for that application. Please note also that this acceptance is based on the 

reported crash performance of your posts and is not meant to address their 

installation, maintenance or repair characteristics. Since your post is a proprietary 

design, the provisions of Section 635.411 (Material or product selection) of Title 23, 

Code of Federal Regulations apply. 

Please do not hesitate to call Mr. Powers at (202) 366-1320 if you have any questions 

regarding this acceptance of your product.

 Sincerely yours,

 (original signed by Michael L. Halladay) 

 Michael L. Halladay

 Acting Program Manager, Safety 

 Enclosure