U.S. Department

of Transportation

Federal Highway

Administration

400 Seventh St., S.W.

Washington, D.C. 20590

September 27, 1994

Refer to: HNG-14

J. M. Essex, P.E.

Vice President, Sales

Energy Absorption Systems, Inc.

One East Wacker Drive

Chicago, Illinois 60601

Dear Mr. Essex:

Your September 7 and September 19 letters provided crash test data on the

TRITON barrier and a summary of encroachment probabilities intended to show

that the TRITON could be expected to perform satisfactorily under many work

zone conditions. Based on these data, you requested that the Federal Highway

Administration (FHWA) accept the TRITON for use at locations where speeds

would be as high as 100 km/h. Our original acceptance letter limited its use

to locations where expected speeds were under 70 km/h. This acceptance was

based on successful completion of the National Cooperative Highway Research

Program (NCHRP) Report 350 test series for a Test Level 2 barrier.

We readily acknowledge that the TRITON, like all longitudinal barriers, is

capable of containing and redirecting vehicles striking it at higher speeds

and lesser angles than those under which it was formally qualified, and that

it is a very forgiving barrier when struck. We further acknowledge that in

some work zones, the likelihood of high-angle, high-speed impacts, or impacts

by large trucks may be low. However, since reliable data on the nature and

extent of roadside encroachments in work zones are limited, we are not in a

position to offer blanket acceptance of TRITON in all 100 km/h situations.

Work zone safety continues to be an FHWA emphasis area and it is in the best

interests of all parties that the level of protection given to motorists and

workers- in construction and maintenance zones remains high. The TRITON

barrier should not be considered an across-the-board substitute for precast

concrete barrier, and it should not be used in locations where impacts by

trucks heavier than 2000 kg are a significant concern.

In direct response to your request, we shall continue to encourage and support

the use of TRITON under any one of the following conditions:

1. In work zones with vehicular speeds of 70 km/h or less.

2. In work zones where the TRITON is used in lieu of cones or

plastic drums.
2

3. In work zones of short duration, regardless of speed, where some risk

to motorists and workers is acknowledged, but considered acceptable

by the agency conducting the work.

In all of the cases suggested above, the roadside surface condition and the

available deflection distance from the barrier to fixed objects, edge dropoffs, and workers must be consistent with TRITON performance characteristics.

This determination can be made from the deflection-impact severity curve which

was submitted with your request and will be sent to FHWA field offices with a

copy of this letter.

Sincerely yours,

Jerry L. Poston

Acting Chief, Federal-Aid and Design Division
TRITON BARRIER Performance

(angled impact test conditions)

CONTACT ENERGY

ABSORPTION SYSTEMS,

INC FOR ANTICIPATED

PERFORMANCE IN THIS

AREA

ACCEPTABLE PERFORMANCE AREA

Impact Speed (km/h)

9/15/94
TRITON Installation Deflection Curves

Impacts in Regions A and B

* Data for curves A and B

were obtained from test

conducted on installation

positioned on a’ clean

asphalt foundation with

less than 5% cross slope

using 820 to 2000 kg

vehicles. When setting up

work zones, the expected

lateral deflection of the

barrier should be accounted

for to ensure maximum

protection of the workers

Impact Severity (kJ)