1200 New Jersey Ave., SE

 Washington, D.C. 20590

December 23, 2011

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

Revised: sf:x62288:12/21/11

 File: h://directory folder/HSST/ CC-123F_Trinity End Terminal TREND

In Reply Refer To:

HSST/ CC-123F

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 (TRENDTM 350), Flared

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

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: SEW25; TREND End Terminal Flared

Decision

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

• The TRENDTM 350 End Terminal, Flared

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, 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 the 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.
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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.

Description

The TRENDTM 350 End Terminal family of products includes the TRENDTM 350 End Terminal, 

Flared. This new product is designed to shield the end of w-beam guardrail in roadside tangent

and flared installations. The flared system is constructed from the same components with the 

only difference being the product’s installation with a flare relative to the edge of road. The 

beginning of length of need (BLON BLON = the point where 20 degree redirection occurs under 

350 guidelines) for the TRENDTM 350 End Terminal, Flared is cited as the third post.

The TRENDTM 350 End Terminal, Flared 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 the front 

of vehicles impacting the nose.

The TRENDTM 350 End Terminal, Flared 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 and also have previously been accepted by the FHWA. The 

TRENDTM 350 End Terminal, Tangent and Flared designs use 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 TRENDTM 350 End 

Terminal, Flared also uses four standard line posts resulting in total system length of 39 feet 2 

inches. The FHWA letters for the above cited components are HSA-10/CC-12F (HBA & Angle 

Strut), HSA-10/CC-12L (W6X8.5 SYTP), and HAS-10/CC-12Q (ET with line posts).

Details of this system are included as an enclosure to this correspondence.

Crash Testing

A. TRENDTM 350 End Terminal; Flared Configuration:

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

Impact speed = 97.0 km/h, Long. ΔV = 9.8 m/s, Long. Ridedown = -17.3 g▲

2. Test 3-35 (2000P/ 100kph/ 20o/ BLON):

Impact speed = 98.3 km/h, Long. ΔV = 6.2 m/s, Long. Ridedown = -11.2 g

▲ Manufacturer noted that the primary accelerometers recorded a value of -

21.2 g for the longitudinal acceleration during Test 3-30 of the TRENDTM 

350 End Terminal in the flared configuration. Analysis of the data and 

the test vehicle revealed that this was due to a wrinkle in the floorboard, 

close to the mounting of the primary accelerometer package. Therefore,

backup accelerometer data (i.e. ; -17.3 g) was used to measure occupant 
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risk for this test, as it more closely matches the rigid body motion of the 

test vehicle, as defined in NCHRP Report 350.

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

Tests 3-31 through 3-34 and Test 3-39 for the flared system were not run. The manufacturer 

requested these tests be waived from the test matrix for the as-stated reasons in Table 1. In 

addition, the manufacturer indicated the TRENDTM 350 End Terminal family of end terminals 

uses a common set of hardware, and this hardware was successfully crash tested as per NCHRP 

Report 350 during the original tangent TRENDTM 350 End Terminal testing.

Table 1. TRENDTM 350 End Terminal Test Matrix, Flared Configuration

Test 

# Illustration Completed Notes

3-30 Yes Passed all Occupant 

Risk Values1

3-31 NO The worst case 

condition for this test is 

a zero degree impact, as 

was run during the 

testing of the 

TRENDTM End 

Terminal in the tangent

configuration. It should 

be noted that an angled 

nose test with the 2000 

kg. test vehicle (Test

3-33) was run during 

the certification of the 

TRENDTM End 

Terminal in the tangent

configuration and the 

results from this test 

passed all of the 

requirements of 

NCHRP 350.
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Test # Illustration Completed Notes 3-32 NO An angled nose test 

with the 820C vehicle 

was run during the 

certification of the 

TRENDTM End 

Terminal in the tangent

configuration and this 

test need not be rerun. 

Test 3-32 for a flared

system is less severe, as 

the angle is greater, 

increasing the 

likelihood that the 

vehicle will gate 

through the system.

3-33 NO An angled nose test 

with the 2000P vehicle 

was run during the 

certification of the 

TRENDTM End 

Terminal in the tangent

configuration and this 

test need not be rerun. 

Test 3-33 for a flared

system is less severe, as 

the angle is greater, 

increasing the 

likelihood that the 

vehicle will gate 

through the system.
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Test 

# Illustration Completed Notes

3-34 NO Test 3-34 (820c) was

successfully run into 

TRENDTM End 

Terminal in the tangent

configuration, with 

smooth vehicle 

redirection and low 

occupant risk values. 

Test 3-35 (2000p) into 

the flared configuration 

also yielded smooth 

vehicle redirection (see 

next test). Due to these 

two successful redirect 

tests, smooth 

redirection and low 

occupant risk values are 

expected for the 820c, 

Test 3-34, into the 

Flared configuration.

3-35 YES Passed all Occupant 

Risk Values

3-39 NO Test 3-39 was run on 

the TRENDTM End 

Terminal in the 

tangent configuration,

which is a worst case 

condition, as the angle 

is greater. The flared

test condition has a 

lower angle and this 

test need not be re-run.

1 The x accelerometer at the vehicle’s c.g. recorded a value of -21.2g’s during this test due to a 

ripple in the floorboard near the accelerometer mounting. The backup x accelerometer 

recorded a maximum value of -17.3 g’s.

Findings

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

concurs that the TRENDTM 350 End Terminal, Flared meets the evaluation criteria for NCHRP 

Report 350 redirective, gating end terminals at TL-3 impact conditions. FHWA also concurs 

with the request for a testing waiver and the reasons for waiver as stated within this 

correspondence.
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Since the TRENDTM 350 End Terminal, Flared was tested with flare rates ranging from 0 

(tangent) to 4 feet of offset, the amount of offset for flared applications can range between the 

tangent position and fully flared. In addition, FHWA also concurs that the testing of the 

TRENDTM 350 End Terminal, Flared was conducted at the worst-case guardrail height of 27-3/4

inches and it is acceptable to use the TREND End Terminal when attached to guardrail with 

heights between 27-3/4 inches and 31 inches. (SGR04a from 27 3⁄4 inches to 30 inches, MGS 

from 27 3⁄4 inches to 31 inches, and the various proprietary 31-inch designs.)

Therefore, the system described and detailed in the attached form is 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 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.

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

a new 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 

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

review, and that it will meet the crashworthiness requirements of the FHWA and the 

NCHRP Report 350.

• To prevent misunderstanding by others, this letter of is designated as number CC-123F

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 TREND End Terminal, Flared is a patented product and is considered proprietary. If 

proprietary devices are specified by 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.
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• 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 letter 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