1200 New Jersey Ave., SE

 Washington, D.C. 20590

December 19, 2011 

FHWA: HSST: WLongstreet: ms: x60087:12/8/11

Revised: sf:x62288:12/19/11

File: h://directory folder/HSST/ C-122 Trinity End Terminal Trend_Median. docx

cc: HSST Will Longstreet 

In Reply Refer To:

HSST/CC-122

Mr. Barry D. Stephens, P.E.

Sr. Vice President Engineering

Energy Absorption Systems

3617 Cincinnati Avenue

Rocklin, CA 95678

Dear Mr. Stephens:

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

review a roadside safety system for eligibility for reimbursement under the Federal-aid highway 

program.

Name of device: Trinity End Terminal Median (TRENDTM 350 Median)

Type of device: W-Beam Redirective, Gating End Terminals

Test Level: NCHRP Report 350 Test Level 3 (TL-3)

Testing conducted by: E-Tech Testing Services, Inc.

Date of request: December 17, 2010 

Date of completed package: October 26, 2011

Task Force 13 Designator: SEW26; TRENDTM 350 Median

Based on a review of crash test results submitted by the manufacturer certifying the device 

described herein meets the crashworthiness criteria of the National Cooperative Highway 

Research Program (NCHRP), Report 350 testing guidelines the device is eligible for 

reimbursement under the Federal-aid highway program. Eligibility for reimbursement under the 

Federal-aid highway program does not establish approval or endorsement by FHWA for any 

particular purpose or use.

The FHWA, the Department of Transportation, and the United States Government do not 

endorse products or services and the issuance of a reimbursement eligibility letter is not an 

endorsement of any product or service

Requirements

Roadside safety devices should meet the guidelines contained in the National Cooperative 

Highway Research Program Report 350 (NCHRP Report 350). The FHWA Memorandum 

“ACTION: Identifying Acceptable Highway Safety Features” of July 24, 1997, provides further 

guidance on crash testing requirements of longitudinal barriers.
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Decision

The following device was found eligible, with details provided below:

• TRENDTM 350 Median

Description

The TRENDTM 350 End Terminal family of products includes the TRENDTM 350 Median. This 

new family of products is designed to shield the end of w-beam guardrail in both roadside 

tangent and flared installations and double sided median installations. The tangent and flared 

systems are constructed from the same components with the only difference being the product’s 

installation with or without a flare relative to the edge of road. The double-sided median system 

uses many of the same components as the TRENDTM 350 Tangent and Flared system; however 

the head, head rails and rail spacers are unique to allow attachment to double-faced guardrail 

found in roadway medians. The beginning of length of need (BLON) for this system is cited as 

the third post. It should be noted that the rail and anchorage components showed their ability to 

redirect impacting vehicles at flare angles of up to 6 degrees during the TRENDTM 350 End 

Terminal, Tangent and Flared test series. Since the TRENDTM 350 Median system is composed 

of the same structural elements, this system can be installed with a flare of up to 6 degrees, 

which corresponds to 3 feet 6 inches for the 5 post system and 2 feet 10 inches for a system that 

is 4 posts in length. 

The TRENDTM 350 Median is based on AASHTO w-beam rail that has been modified to include 

slots. These slots extend the length of the rail from the guardrail bolts that hold the rail together. 

When an errant vehicle strikes the impact head of the terminal in an end on impact, the vehicle’s 

energy is safely absorbed by the terminal’s rail sections as each of the adjacent pairs of rail 

sections slide past each other. The vehicle’s kinetic energy is dissipated by tearing of the panel 

slots, re-shaping of the panels by a calibrated fin at the back of each panel, and by friction. A 

lightweight impact head is attached to the front of the unit to engage impacting vehicles and to 

control potential vehicle spearing by the downstream guardrail.

The TRENDTM 350 Median uses end terminal posts and anchorage components that were 

previously tested to NCHRP 350. These posts designs, known as the Hinged Breakaway 

Assembly (HBA) and Steel Yielding Terminal Post (SYTP), have seen extensive use in the ET 

family of end terminals previously accepted by the FHWA. The TRENDTM 350 Median uses an 

HBA post in the first post position and an SYTP post in the second post position. These first two 

posts are joined together by another standard end terminal component, the Angle Strut. The 

remaining system posts are standard line posts, proven in a number of products. The TRENDTM 

350 Median uses two line posts, resulting in total length of 26 feet 11 inches. Past FHWA letters 

for the above cited components are HSA-10/CC-12F (HBA and Angle Strut), HSA-10/CC-12L 

(W6X8.5 SYTP), and HAS-10/CC-12Q (ET with line posts).
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Details of this system are included as an enclosure to this correspondence.

Crash Testing

The following NCHRP Report 350 tests were completed for FHWA review of the TREND 

Median End Terminal:

TRENDTM 350 Median End Terminal:

• Test 3-30 (820C/ 100kph/ 0o/ w/4 Offset):

Impact speed = 97.0 km/h, Long. ΔV = 11.3 m/s, Long. Ridedown = -18.4 g

• Test 3-31 (2000P/ 100kph/ 0o/ Nose):

Impact speed = 96.4 km/h, Long. ΔV = 8.2 m/s, Long. Ridedown = -11.3 g

• Test 3-31 (2000P/ 100kph/ 0o/ Nose):

Impact speed = 100.4 km/h, Long. ΔV = 8.4 m/s, Long. Ridedown = -10.2 g

Tests 3-32 through 3-35 and Test 3-39 were not run for the TRENDTM 350 Median as the 

manufacturer requests these tests be waived based upon the following reasons, as stated in Table 

1. In addition, it is noted that Test 3-31 for the TRENDTM 350 Median End Terminal was 

conducted twice. This test was first run with a system that had a total five (5) posts at 33 feet 2 

inches in length. This test demonstrated that the system had excess capacity and therefore Test 

3-31 was re-conducted with a system that had a total of four (4) posts at 26 feet 11 inches in 

length. As noted above, this test also resulted in satisfactory occupant risk values.

Test summaries of the above tests are included as an enclosure to this correspondence.

Table 1. Trinity End Terminal (TRENDTM 350), Test Matrix

Test # Illustration Completed Notes

3-30 YES Passed all Occupant Risk 

Values.

3-31 

(1)

YES 5-Bay System

Passed all Occupant Risk 

Values.

3-31 

(2)

YES 4-Bay System

Passed all Occupant Risk 

Values.
4

Test # Illustration Completed Notes 3-32 NO Test 3-30, which was run 

on the TRENDTM 350

Median, is worst case for 

a gating energy 

absorbing terminal. Test 3-32 was run on the

single sided system in 

the tangent configuration 

and this test need not be 

re-run.

3-33 NO Test 3-31, which was run 

on the TRENDTM 350

Median is worst case for 

a gating energy 

absorbing terminal. Test 3-33 was run on the 

single sided system in 

the tangent configuration 

and this test need not be 

re-run.

3-34 NO This test was passed on 

the single sided system

in the tangent

configuration. The single 

sided system test is worst 

case, as there are less 

structural elements 

resisting the impact.

3-35 NO This test was passed on 

the single sided 

TRENDTM 350 End 

Terminal installed in 

both the flared and 

tangent configurations. 

These single sided 

system tests are worst 

case, as there are less 

structural elements 

resisting the impact.
5

Test # Illustration Completed Notes

3-39 NO This test was passed on 

the single sided 

TRENDTM 350 End 

Terminal in the tangent

configuration and the 

structural elements the 

vehicle impacts have not 

changed. The single 

sided system test is worst 

case, as there are less 

structural elements 

resisting the impact.

Findings

Based on the successful completion of the described NCHRP Report 350 testing, FHWA concurs 

that the TRENDTM 350 Median End Terminal meets the evaluation criteria for NCHRP Report 350 

redirective, gating end terminals at TL-3 impact conditions. The FHWA also concurs with the 

request for a testing waiver of NCHRP Report 350 test numbers 3-32, 3-33, 3-34, 3-35, and 3-39 

and the provided reasons for the waiver for each of these test numbers as stated within this 

correspondence.

In addition, FHWA concurs that the testing of the TRENDTM 350 End Terminal family of end 

terminals was conducted at the worst-case guardrail height of 27-3/4 inches and it is acceptable 

to use the TRENDTM 350 Median End Terminal when attached to guardrail with heights between 

27-3/4 inches and 31 inches (SGM04a-b from 27 3⁄4 inches to 30 inches, MGS from 27 3⁄4 inches 

to 31 inches, and the various proprietary 31-inch designs.)

The FHWA also notes that the rail and anchorage components showed their ability to redirect 

impacting vehicles at flare angles of up to 6 degrees during the TRENDTM 350 End Terminal, 

Tangent and Flared test series. Since the TRENDTM 350 Median system is composed of the 

same structural elements, this system can be installed with a flare of up to 6 degrees, which 

corresponds to 3 feet 6 inches for the 5 post system and 2 feet 10 inches for a system that is 4 

posts in length. 

Therefore, these systems as described are eligible for reimbursement and should be installed 

under the range of conditions tested, when such use is acceptable to a highway agency.

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

• This letter includes an AASHTO/ARTBA/AGC Task Force 13 designator that should be 

used to identify any new or updated Task Force 13 drawings. 

• This finding of eligibility is limited to the crashworthiness characteristics of the devices 

and does not cover their structural features, or conformity with the Manual on Uniform 

Traffic Control Devices.
6

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

reimbursement eligibility letter.

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

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

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

modify or revoke this letter.

• 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 the 

same chemistry, mechanical properties, and geometry as that submitted for review, and 

that it will meet the crashworthiness requirements of the NCHRP Report 350.

• To prevent misunderstanding by others, this letter is designated as number CC-122, 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 TRENDTM 350 Median is a patented product and considered proprietary. If 

proprietary devices are specified by highway agency for use on Federal-aid 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 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 holder. 

The finding of eligibility is limited to the crashworthiness characteristics of the candidate 

device, 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,

Michael S. Griffith 

Director, Office of Safety Technologies

Office of Safety 

Enclosures