June 24, 2002

Refer to: HSA-10/CC12J

Hayes E. Ross, Jr., P.E., Ph. D.

Texas Transportation Institute

The Texas A&M University System

3135 TAMU

College Station, TX 77843-3135

Dear Dr. Ross:

In your February 11 letter to Mr. Michael Halladay, former Acting
Program Manager for Safety, you requested the Federal Highway
Administration=s (FHWA) acceptance of an alternative breakaway steel
post system for use with currently-accepted versions of the ET-2000,
including those using the ET-PLUS extruder head. To support your
request, you included copies of the Texas Transportation Institute (TTI)
October 2001 report, ANCHRP Report 350 Testing and Evaluation of the
ET-PLUS with Steel Cable Release Post and Steel Yielding Terminal Posts@
and videotapes of the two crash tests included in that report. After
reviewing the information you submitted, Mr. Richard Powers of my staff
recommended that an additional test be conducted. The results of that
test were documented in TTI=s June 2002 report, ANCHRP Report 350 Test
3-34 of the ET-PLUS with Steel Cable Release Post and Steel Yielding
Terminal Posts@ which was received on June 7.

Your first new post (named the cable release post or CRP) is a two-piece
W150 x 14 steel section with a 1981-mm long base section in the ground
and a 902-mm long upper section. The two sections are reinforced at the
ground line to provide adequate anchorage strength for downstream hits
but are designed to release the cable anchor quickly when the post is
struck in an end-on type impact. It is used as the terminal end post.
The next seven posts are used between the anchor post and the first
standard line post as an alternative to the original wooden CRT posts or
to the all-steel HBA breakaway posts that have also been found
acceptable. These new posts are named steel yielding terminal posts or
SYTP and are one-piece W200 x 15 hot-rolled steel sections 1830-mm long.
The SYTP posts are modified by drilling two 21-mm diameter holes through
each flange at the ground line. This modification results in a post that
is similar to standard guardrail posts along its strong axis
(perpendicular to the guardrail installation), but significantly weaker
along its weak axis (parallel to the installation). Enclosure 1 contains
detailed dimensions for the CRP and SYTP posts.

You successfully conducted NCHRP Report 350 tests 3-30, 3-34, and 3-35
using the new posts. Enclosure 2 shows the summary results of each of
these tests. My staff agreed that the remaining tests could be waived,
based on a review of previous testing of various ET-2000 configurations
and the results of the tests noted above.

Based on staff analysis of the information you provided, the CRP/SYTP
post and anchor system is acceptable for use on the national Highway
System. I also agree that the CRP post, as described herein, may be used
alone as the anchor post with all previously-accepted versions of the
ET-2000 terminal as you requested. The remaining breakaway posts used
with any of the previously accepted ET-2000 designs may be the original
CRT weakened wood posts, the two-piece steel HBA posts, or the new SYTP
posts. Although all three types of breakaway posts are similar, I am
reluctant to endorse any random combination of breakaway posts in the
same terminal installation, particularly given the significantly higher
strong-axis moment capacity of the SYTP posts. For new installations
there is no reason to use a Amix and match@ approach, and damaged
terminals are best repaired in-kind or replaced with a fully-tested
design to minimize an agency=s liability.

Sincerely yours,

(original signed by Harry W. Taylor)

*for*

Carol H. Jacoby, P. E.

Director, Office of safety Design

2 Enclosures