August 17, 2001

Mr. Daniel J. MacDonald					Refer to: HSA-10/B-86
Standards Engineer
Oregon Department of Transportation
222 Transportation Building
Salem, Oregon 97310

Dear Mr. MacDonald:

The information on the Oregon precast barrier that you sent with your May 25 letter was forwarded 
to my staff for review.  Although the tested barrier, an 810-mm tall, 3.84-m long F-shape barrier with 
a pin and loop connection, appeared to meet all evaluation criteria contained in the National 
Cooperative Highway Research Program (NCHRP) Report 350 at test level 3 (TL-3), the test report, 
prepared by KARKO Engineering Automotive Research Center, did not contain all of the 
information recommended in Chapter 6 of NCHRP Report 350.  The most obvious omission was the 
lack of a detailed description of the test article, including internal reinforcing and connection details, 
and there were questions concerning the accuracy of some of the data. 

On July 26, you sent Mr. Richard Powers copies of revised reports, both for the original 810-mm 
barrier (Test Report No. KAR21007-01) and for a subsequent test of a 1065-mm tall precast concrete 
barrier (Test Report No. KAR21007-02).  Descriptions of each of these designs and their crash 
performance are as follows: 

Standard barrier: test installation consisted of 16 precast concrete F-shape segments, each 810-mm 
high, 3.8-m long, 610-mm wide at the base, and 240-mm wide at the top.  The pin and loop 
connection consisted of two 19-mm A36 steel loops near the top of one segment end, above a single 
19-mm steel loop near the bottom on the same end.  The corresponding  loops on the adjacent barrier 
segment consisted of a single loop near the top and double loops on the bottom.  When placed 
together, the single loops fit between the double loops, forming two connection points, each consisting 
of three loops.  A 25-mm diameter , 735-mm long ASTM A449 steel pin, with no nut or retention 
device, was dropped through the loops to complete the connection.  This system was impacted near 
its midpoint with a 2000-kg pickup truck at 100.7 km/h and a 25 degree angle.  Occupant impact 
velocity was reported to be 5.8 m/sec and maximum 10-millisecond ridedown acceleration was 18.2 
g's.  The maximum roll angle of the vehicle was less than 15 degrees and the barrier dynamic 
deflection was only 762 mm.  This design is shown in Enclosure 1.

Tall barrier:  test installation consisted of 20 precast concrete F-shape segments, each 1065-mm high, 
3.02-m long, 660-mm wide at the base, and 230-mm wide at the top.  The connection between 
segments consisted of two sets of two perforated C-shape steel channels with the open sides 
alternately positioned such that one leg of each channel fits between the legs of the mating channel on 
the adjacent barrier segment.  A 25-mm diameter ASTM A449 end bolt, 760-mm long, was inserted 
through holes in each C-channel leg and into a nut welded to the bottom of the lower C-channel, 
effectively forming eight points of connection.  This system was impacted near its midpoint with a 
2000-kg pickup truck at 102.4 km/h and a 25 degree angle.  Occupant impact velocity was reported 
to be 6.2 m/sec and maximum 10-millisecond ridedown acceleration was 19.4 g's.  Maximum vehicle 
roll was approximately 16 degrees and the barrier dynamic deflection was 813 mm.  This design is 
shown in Enclosure 2.

Based on the reported results of the tests run on these barriers, both the 810-mm tall and the 1065-
mm tall designs are considered to meet the evaluation criteria of the National Cooperative Highway 
Research Program (NCHRP) Report 350 at test level 3 (TL-3) and may be used on the National 
Highway System when such use is acceptable to the contracting authority.  Both barriers exhibited 
the least amount of deflection and resulted in the most stable, post-impact vehicle trajectories of any 
free-standing, precast barrier tested to date.  I understand that the drawings for these non-
proprietary barriers can be obtained by contacting you at (503) 986-3779 or from your web site at 
ftp://ftp.odot.state.or.us/techserv/roadway/standards  under drawing nos. odot_apwa500.pdf and 
odot_apwa545.pdf. 


Sincerely yours,


				(original signed by  Frederick G. Wright, Jr.)
			
				Frederick G. Wright, Jr.
				Program Manager, Safety
2 Enclosures