1200 New Jersey Avenue, SE. 

Washington, DC 20590 July 16, 2007 

In Reply Refer To: HSSD/B-177 

Mr. Brian Smith 

Trinity Highway Products, LLC 

PO Box 568887 

Dallas, TX 75356-8887 

Dear Mr. Smith: 

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

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

 Name of system: Trinity Guardrail System (TGS) 

 Type of system: 31 inch strong post w-beam longitudinal barrier 

Test Level: National Cooperative Highway Research Program 

(NCHRP) Report 350 and Manual for Assessing Safety 

Hardware 2008 (MASH-08) Test Level 3 

 Testing conducted by: Texas Transportation Institute 

 Date of request: November 13, 2007 

 Additional information received: April 28, 2008 

 Date of completed package: June 20, 2008 

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

NCHRP Report 350 “Recommended Procedures for the Safety Performance Evaluation of 

Highway Features” and the proposed American Association of State Highway and 

Transportation Officials’ MASH-08. 

Requirements

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

"Recommended Procedures for the Safety Performance Evaluation of Highway Features." 

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

1997, provides further guidance on crash testing requirements of longitudinal barriers. You have 

also chosen to anticipate the adoption of the MASH-08, an option that the FHWA has offered 

with the understanding that additional testing may need to be done if changes to the test criteria 

are made before the MASH-08 is formally adopted. 

Description 

The TGS is a non-blocked-out strong post w-beam longitudinal barrier system that consists of 

3.81 m (12 foot 6 inch) long, 12 gage w-beam rails supported on 1.83 m (6 foot 0 inch) long 

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W150 x 12.6 (W6 x 8.5#) standard (non-weakened) line posts spaced 1.905 m (6 feet 3 inches) 

on center. Measured from the ground level the heights of the top of the posts and the top edge of 

the w-beam are 813 mm (32 inches) and 787 mm (31 inches) respectively. W-beam rail splices 

are located at the posts. 

The FHWA previously accepted Trinity’s 31-inch high non-blocked-out strong post w-beam 

barrier that used steel yielding line posts with splices located at mid-span (FHWA Acceptance 

Letter B-140 dated November 2, 2005). 

Crash Testing 

Two full scale crash tests were conducted on a 53 m (175 foot) length of the TGS: 

1. NCHRP Report 350 Test 3-10, (820C, 100 km/hr, 20 degrees) and 

2. MASH-08 Test 3-11 (2270P, 100 km/hr, 25 degrees) 

In both tests the rail splices were located at the posts with no Flange Protector (backup plate) in 

use. In test No. 1 the rails were attached to the posts with 16 mm x 44 mm (5/8 x 1 3⁄4 inch) 

slotted countersunk head bolts that were previously used in testing the Trinity T-31 and T-39 

barrier systems. In test No. 2 the rails were attached to the posts with 16 mm x 44 mm (5/8 x 

2 inch) countersunk head bolts with an elongated shaft. You plan on using only the 16 mm x 

44 mm (5/8 x 1 3⁄4 inch) slotted countersunk head bolt as this bolt allowed the rail to release from 

the post more readily during testing. 

Findings 

You requested acceptance under both the NCHRP Report 350 and the MASH-08 criteria. Tests 

No. 1 and No. 2 noted above and detailed in the enclosed Test data summary sheets met the test 

and evaluation criteria of the NCHRP Report 350 and the Proposed MASH-08, respectively. At 

our request you provided the overhead view of test No. 1 that showed the small car redirected by 

the barrier through a yaw of 140 degrees. However we found no evidence of hard snagging on 

any post and the vehicle trajectory was comparable to that seen in other accepted barrier systems. 

The MASH-08 test 3-10 of the 1100C impacting at 25 degrees was waived as previously agreed 

by the FHWA because of the pair of 3-10 tests conducted on the T-31 system. Those tests 

showed the 820C impact resulted in higher occupant impact velocities and ridedown 

accelerations. We concur that the 820C test is the ‘worst case scenario’ for the TGS as well. 

The Report 350 Test 3-11 was waived as previously agreed by the FHWA because of the greater 

impact severity of the 2270 kg pickup truck. Although it is known that the 2000P vehicle is 

structurally less stable we concurred in your contention that the heavier truck would be most 

likely to fail the system due to increased dynamic deflection. 

Therefore, the system described above and detailed in the enclosed drawings is acceptable for 

use on the NHS under the range of conditions tested, when such use is acceptable to a highway 

agency. The maximum dynamic deflection measured in test 3-11 was 980 mm (38.4 inches) and 

the ‘working width’ was 1040 mm (40.9 inches.) 

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You also requested 2 m post spacing be allowed for use in countries that follow the metric 

system, as we permitted you to do on the T-31 and T-39 systems. As the standard USA spacing 

is 1.905 m we consider the 5 percent additional distance between the posts to be acceptable. 

Please note the following standard provisions that apply to the 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 hardware furnished has essentially 

the same chemistry, mechanical properties, and geometry as that submitted for acceptance, 

and that it 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-177 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. 

• The TGS 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, they: (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 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 yours, 

 David A. Nicol, P.E. 

 Director, Office of Safety Design 

 Office of Safety 

Enclosure 

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0.000 s 0.122 s 0.245 s 

General Information Test Agency...............................  Test No. ....................................  Date ........................................... Test Article Type...........................................  Name .........................................  Total Installation Length ............  Key Elements  Description .............................  Height ..................................... Soil Type and Condition............. Test Vehicle Type/Designation.......................  Make/Model ...............................  Mass  Curb........................................  Test Inertial.............................  Dummy...................................  Gross Static............................ 

Texas Transportation Institute 400001-TGS2 06-08-2007 Longitudinal Barrier Trinity Guardrail System (TGS) 175 ft W-Beam on W6x8.5 x 72 inch long posts, splices at posts, no blockouts, no flange protectors 31 inches Standard Soil, Damp (9.8%) 820C 1997 Chevrolet Metro 1832 lb 1830 lb  170 lb 2000 lb 

Impact Conditions  Speed ....................................... Angle.......................................... Location/Orientation ..................Exit Conditions Speed ........................................ Angle..........................................Post Impact Trajectory Vehicle Stability ......................... Stopping Distance .....................Vehicle Snagging........................Vehicle Pocketing .......................Post-Impact Behavior (during 1.0 sec after impact)  Max. Yaw Angle ..................... Max. Pitch Angle .................... Max. Roll Angle ......................Test Article Deflections

 Dynamic..................................... Permanent ................................. Working Width ...........................

61.1 mi/h 19.7 degrees Btw Post 11 and 1228.8 mi/h  9.3 degrees Satisfactory Btw Post 21 and 226 ft laterally front None None 26 degrees  -6 degrees 13 degrees 19.4 inches  9.6 inches 22.2 inches 

Occupant Risk Values Impact Velocity  Longitudinal............. Lateral ..................... Ridedown Acceleration Longitudinal............. Lateral ..................... THIV ........................... PHD............................Max. 0.050-s Average  Longitudinal............. Lateral ..................... Vertical ....................Vehicle Damage VDS............................ CDC............................ Max. Exterior  Vehicle Crush.......... OCDI .......................... Max. Occupant Compa Deformation.............

Figure 6.7. Summary of results for NCHRP Report 350 test 3-10 on the TGS. 

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General Information Test Agency...............................  Test No. ....................................  Date ........................................... Test Article Type...........................................  Name .........................................  Total Installation Length ............  Key Elements  Description .............................  Height ..................................... Soil Type and Condition............. Test Vehicle Type/Designation.......................  Make/Model ...............................  Mass  Curb........................................  Test Inertial.............................  Dummy...................................  Gross Static............................ 

Texas Transportation Institute 400001-TGS1 05-31-2007 Longitudinal Barrier Trinity Guardrail System (TGS) 175 ft W-Beam on W6x8.5 x 72 inch long posts, splices at posts, no blockouts, no flange protectors 31 inches Standard Soil, Damp (9.8%) 2270P 2002 Dodge Ram 1500 Pickup 4726 lb 4970 lb No dummy 4970 lb 

Impact Conditions  Speed ....................................... Angle.......................................... Location/Orientation ..................Exit Conditions Speed ........................................ Angle..........................................Post Impact Trajectory Vehicle Stability ......................... Stopping Distance .....................Vehicle Snagging........................Vehicle Pocketing .......................Post-Impact Behavior (during 1.0 sec after impact)  Max. Yaw Angle ..................... Max. Pitch Angle .................... Max. Roll Angle ......................Test Article Deflections

 Dynamic..................................... Permanent ................................. Working Width ...........................

63.3 mi/h 23.8 degrees At Post 11 36.6 mi/h 18.4 degrees Satisfactory 175 ft downstream 50 ft laterally front None None -37 degrees  2 degrees -13 degrees 38.4 inches 31.0 inches 40.9 inches 

Occupant Risk Values Impact Velocity  Longitudinal............. Lateral ..................... Ridedown Acceleration Longitudinal............. Lateral ..................... THIV ........................... PHD............................Max. 0.050-s Average  Longitudinal............. Lateral ..................... Vertical ....................Vehicle Damage VDS............................ CDC............................ Max. Exterior  Vehicle Crush.......... OCDI .......................... Max. Occupant Compa Deformation.............

Figure 5.7. Summary of results for NCHRP Report 350 Update test 3-11 on the TGS. 

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