May 7, 1998

Refer to: HNG-14

J. M. Essex, P.E.

Senior Vice President, Sales

Energy Absorption Systems, Inc.

One East Wacker Drive

Chicago, Illinois 60601

Dear Mr. Essex:

In your April 1 letter to Mr. Henry Rentz, Director of the Federal Highway Administration’s

Office of Engineering, you requested acceptance of a modified Triton Barrier as a National

Cooperative Highway Research Program (NCHRP) Report 350 test level 3 (TL-3) temporary

barrier. Your letter also requested FHWA acceptance of a further-modified Triton configuration

to function as a TL-3 terminal for the barrier. This second request will be addressed in a separate

letter.

To support your request for acceptance of the Triton Barrier at TL-3, you also sent copies of

your December 19, 1997, report entitled “TRITON BARRIER TL-3: Qualification to NCHRP

350 Test Level 3 - Engineering Summary,” which included the full report prepared by E-TECH

Testing Services, Inc., entitled “NCHRP Report 350 Crash Test Results for the TRITON

BARRIER TL-3,” dated December 1997, and a video tape showing the full scale tests that you

conducted on the modified Triton Barrier. We noted that the Triton Barrier TL-3 modules have

the same exterior dimensions as those tested earlier to obtain TL-2 acceptance but that the

interior U-bolts at the ends of each module are double-nutted to the interior steel framework in

the TL-3 units. Each module is set on two 178-mm high plastic pedestals to raise its center of

gravity in order to meet TL-3 evaluation criteria. These pedestals are strapped to each individual

unit and are also tethered together (in groups of ten) with a braided polyester cord to reduce

debris scatter following an impact. We understand that all new modules will be made with the

two-nut connection noted above and that all pedestals shipped to the field separately for use with

earlier-manufactured modules will include extra nuts and instructions to modify any existing

segments that have only a single nut connection. Enclosure 1 shows the details of the TL-3

design. 

NCHRP Report 350 recommends two tests for longitudinal barriers: tests 3-10 and 3-11, the first

being an 820-kg car impacting at 100 km/h and at a 20-degree angle and the second being a 2000-

kg pickup truck impacting at 100 km/h and at a 25-degree angle. You ran test 3-11 twice to

determine the number of modules needed in advance of the barrier length of need to ensure

vehicle containment. In the first test, the vehicle impacted near the center of a 30-module array. 

In the second, the impact point was between modules ten and eleven. You then concluded that at

least ten water-filled modules are needed in advance of the barrier length of need. 

Although both strength tests met NCHRP Report 350 evaluation criteria, barrier deflection was
reported as 5.8 and 6.9 meters, respectively. You then ran a non-standard test to determine the

outcome of a more typical hit. When impacted with a 2000-kg pickup truck at 100 km/h and 7

degrees, the truck was contained and redirected parallel to the barrier, which deflected only 1.4

meters. User agencies should be informed of the range of deflections to be expected and advised

to ensure that these distances are available in any given work zone or that the likelihood of high

angle (or heavy vehicle) impacts is low enough to result in an acceptable risk when lesser

clearances are available. The results of each of the four tests you reported are shown in Enclosure

2.

Based on our review of the information you provided, we concur that the Triton Barrier, as

modified and tested, meets the acceptance criteria for an NCHRP Report 350 TL-3 longitudinal

barrier. Because it is a proprietary device, its use on Federal-aid projects, except exempt, nonNational Highway System projects, remains subject to the conditions listed in Title 23, Code of

Federal Regulations, Section 635.411 when such use is specified by the contracting authority.

Sincerely yours,

(original signed by Dwight A. Horne)

Dwight A. Horne

Chief, Federal-Aid and Design Division

2 Enclosures

Acceptance letter B-48