1200 New Jersey Ave., SE

 Washington, D.C. 20590

August 19, 2011

FHWA: HSSI: WLongstreet: ms: x60087:6/8/11

File: h: //directory folder/HSST/ CC-68A Thrie Beam Bullnose Guardrail 

System.docx

cc: HSST Will Longstreet 

In Reply Refer To:

HSST/ CC-68A

Mr. Dean L. Sicking, Ph.D., P.E. Director, 

Midwest Roadside Safety Facility University 

of Nebraska - Lincoln P.O. Box 880601 

Lincoln, NE 68588-0601

This letter is in response to Messrs. Bielenburg's and Faller's request for the Federal 

Highway Administration (FHWA) acceptance of an alternative post design for the Thrie 

beam bullnose median barrier (bullnose attenuator) for use on the National Highway System 

(NHS).

Name of system: Thrie beam bullnose guardrail system

Type of system: Non-Gating Crash Cushion/Impact Attenuator

Test Level: NCHRP Report 350 Test Level 3

Testing conducted by: Midwest Roadside Safety Facility

Date of request: December 21, 2010

Date initially acknowledged: December 22, 2010

Task Force 13 Designator: SET03b

You requested that we find a steel post design to be an acceptable alternative to the 

previously-accepted wood post Thrie beam bullnose attenuator for use on the NHS under the 

provisions of the National Cooperative Highway Research Program (NCHRP) Report 350.

Requirements

Roadside safety devices should meet the guidelines contained in NCHRP Report 350 if tested 

prior to January 1, 2011, and the guidelines in American Association of State Highway 

Transportation Official's (AASHTO) Manual for Assessing Safety Hardware if tested after that 

date. The FHWA memorandum "ACTION: Identifying Acceptable Highway Safety Features" 

of July 24, 1997, provides further guidance on crash testing requirements of longitudinal barriers 

and crash cushions.

Decision

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

• Thrie beam Bullnose Barrier with Universal Breakaway Steel Posts (UBSP)
2

Description

The steel post design of the bullnose attenuator is essentially identical to the original wood post 

design that was accepted for use on the NHS in FHWA acceptance letter CC-68, dated November 

8, 2000. The design consists of five slotted Thrie beam rail elements: the nose piece with a 1580-

mm (62-3/16-inch) radius, two sections (one on each end of the nose section) with 10400-mm (409-

7/16-inch) radii, and one straight rail section on each end of the second sections. Two 5/8-inch 

diameter steel cables are set behind the top two corrugations in the nose piece. Posts 1 and 2 are 

wood BCT-type posts and effectively anchor the bullnose in side impacts. In the modified design, 

the original CRT posts (numbered 3 through 8) have been replaced with the new UBSP. The lower 

section of the UBSP consists of a 6 inch x 8 inch x 3/16 inch ASTM A500 Grade B steel foundation 

tube with the lower base plate. The upper portion of the UBSP is a W6 x 8.5 post with the upper 

base plate. The plates are connected with 7/16-inch diameter ASTM A325 threaded hex bolts. 

Drawings showing the overall layout of the Bullnose design and the UBSP posts are shown in 

Enclosure 1.

Crash Testing

Since the UBSP design of the bullnose attenuator was essentially unchanged from the previously 

accepted CRT post version, you needed only to show that the new post system would not adversely 

affect the crash performance of the unit. You concluded that NCHRP Report 350 tests 3-30,3-31, 

and 3-38 were those most likely to be effected by the post substitution and that the remaining tests 

for a redirective crash cushion need not be rerun. After discussing the test matrix with Mr. 

Bielenberg, FHWA agreed that the remaining tests would be redundant and accepted the three tests 

described below as adequate and sufficient to verify crashworthiness of the UBSP design.

Test 3-30 required a 100 km/h impact by a 1800 lb (820-kg) passenger car impacting at 62 mph (100 

km/h) directly into the nose of the barrier with a 1/4-point offset. In test no. USPBN-3, the car was 

captured by the bullnose with little roll or pitch. As shown in Enclosure 2, maximum occupant 

impact velocity was 33.6 feet/s (10.2 m/s) and the ridedown acceleration was 7.7 g's. The vehicle 

was brought to a stop approximately 21 ft from the first impact point.

Test 3-31 was run as test no. USPBN-4 and consisted of a 4429-lb (2009-kg) pickup truck 

impacting the Bullnose Attenuator head-on at 64.5 mph (103.7 km/h). The truck was captured by the 

barrier and brought to a stop in approximately 51 feet. Occupant Impact Velocity (OIV) was reported 

to be 21.8 feet/s (6.6 m/s) and the maximum acceleration was under 8 g's. Enclosure 3 is the 

summary sheet for this test.

Test 3-38 also required a 100 km/h 2000-kg pickup truck test, but into the side of the Bullnose 

Attenuator at its critical impact point (CIP). The Midwest Roadside Safety Facility test number 

USPBN-2 reported a 2029-kg (4472-lb) truck struck the barrier at 101.3 km/h (62.9 km/h) and 21.7 

degrees. The OIV was 8.6 m/sec (longitudinal) and the Ridedown Acceleration was approximately 

15 g's. Vehicular roll, pitch and yaw were recorded as 12.6, 5.9, and 20.7 degrees, respectively. The 

truck came to rest within the bullnose envelope, 28 feet (8.7 m) downstream from the initial impact 

point. Enclosure 4 is the summary sheet for this test.

Findings

The Thrie beam Bullnose Attenuator with UBSP as described above is acceptable for use on the 

NHS as a non-gating crash cushion primarily used to shield rigid objects located in the medians of 

divided highways. 
3

The conditions listed in the original acceptance letter remain in effect and are repeated here for 

ready reference:

• The leading edge of the bullnose should be installed a minimum distance of 19 m in 

advance of any shielded object or hazard.

• If transitioned to a bridge railing or parapet, the transition should begin no sooner than post 9, 

measured from the nose of the installation

• If an asymmetrical design is used (refer to CC-68 for details), the barrier flare rates on the 

approaching traffic side should not exceed the AASHTO Roadside Design Guide 

recommendations

• The bullnose attenuator should be installed on relatively flat ground (e.g. 10H:1V or 

flatter) to ensure optimal crash performance.

Please note the following standard provisions that generally apply to all FHWA letters of 

acceptance:

• This acceptance letter includes an AASHTO/ARTBA/AGC Task Force 13 designator that 

should be used when creating a new or revised Task Force 13 drawing.

• This acceptance is limited to the crash worthiness characteristics of the systems and does not 

cover their structural features, nor conformity with the Manual on Uniform Traffic Control 

Devices (when applicable).

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

new acceptance letter.

• Should the FHWA discover that the qualification testing was flawed, that in-service 

performance reveals unacceptable safety problems, or that the system being marketed is 

significantly different from the version that was crash tested, we reserve the right to modify 

or revoke our acceptance.

• 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 acceptance, 

and that it will meet the crashworthiness requirements of the FHWA and NCHRP Report 

350.

• To prevent misunderstanding by others, this letter of acceptance is designated as number CC68 A 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 Thrie beam Bullnose Attenuator is not a patented product, nor is it considered 

proprietary. However, if any proprietary devices are specified by a 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. 
4

• This acceptance letter shall not be construed as authorization or consent by the FHWA to use, 

manufacture, or sell any patented system for which the applicant is not the patent holder. 

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 

Enclosures 
 1200 New Jersey Ave., SE

 Washington, D.C. 20590

August 19, 2011

In Reply Refer To:

HSST/ CC-68A

Mr. Dean L. Sicking, Ph.D., P.E. Director, 

Midwest Roadside Safety Facility University 

of Nebraska - Lincoln P.O. Box 880601 

Lincoln, NE 68588-0601

This letter is in response to Messrs. Bielenburg's and Faller's request for the Federal 

Highway Administration (FHWA) acceptance of an alternative post design for the Thrie 

beam bullnose median barrier (bullnose attenuator) for use on the National Highway System 

(NHS).

Name of system: Thrie beam bullnose guardrail system

Type of system: Non-Gating Crash Cushion/Impact Attenuator

Test Level: NCHRP Report 350 Test Level 3

Testing conducted by: Midwest Roadside Safety Facility

Date of request: December 21, 2010

Date initially acknowledged: December 22, 2010

Task Force 13 Designator: SET03b

You requested that we find a steel post design to be an acceptable alternative to the 

previously-accepted wood post Thrie beam bullnose attenuator for use on the NHS under the 

provisions of the National Cooperative Highway Research Program (NCHRP) Report 350.

Requirements

Roadside safety devices should meet the guidelines contained in NCHRP Report 350 if tested 

prior to January 1, 2011, and the guidelines in American Association of State Highway 

Transportation Official's (AASHTO) Manual for Assessing Safety Hardware if tested after that 

date. The FHWA memorandum "ACTION: Identifying Acceptable Highway Safety Features" 

of July 24, 1997, provides further guidance on crash testing requirements of longitudinal barriers 

and crash cushions.

Decision

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

• Thrie beam Bullnose Barrier with Universal Breakaway Steel Posts (UBSP)
2

Description

The steel post design of the bullnose attenuator is essentially identical to the original wood post 

design that was accepted for use on the NHS in FHWA acceptance letter CC-68, dated November 

8, 2000. The design consists of five slotted Thrie beam rail elements: the nose piece with a 1580-

mm (62-3/16-inch) radius, two sections (one on each end of the nose section) with 10400-mm (409-

7/16-inch) radii, and one straight rail section on each end of the second sections. Two 5/8-inch 

diameter steel cables are set behind the top two corrugations in the nose piece. Posts 1 and 2 are 

wood BCT-type posts and effectively anchor the bullnose in side impacts. In the modified design, 

the original CRT posts (numbered 3 through 8) have been replaced with the new UBSP. The lower 

section of the UBSP consists of a 6 inch x 8 inch x 3/16 inch ASTM A500 Grade B steel foundation 

tube with the lower base plate. The upper portion of the UBSP is a W6 x 8.5 post with the upper 

base plate. The plates are connected with 7/16-inch diameter ASTM A325 threaded hex bolts. 

Drawings showing the overall layout of the Bullnose design and the UBSP posts are shown in 

Enclosure 1.

Crash Testing

Since the UBSP design of the bullnose attenuator was essentially unchanged from the previously 

accepted CRT post version, you needed only to show that the new post system would not adversely 

affect the crash performance of the unit. You concluded that NCHRP Report 350 tests 3-30,3-31, 

and 3-38 were those most likely to be effected by the post substitution and that the remaining tests 

for a redirective crash cushion need not be rerun. After discussing the test matrix with Mr. 

Bielenberg, FHWA agreed that the remaining tests would be redundant and accepted the three tests 

described below as adequate and sufficient to verify crashworthiness of the UBSP design.

Test 3-30 required a 100 km/h impact by a 1800 lb (820-kg) passenger car impacting at 62 mph (100 

km/h) directly into the nose of the barrier with a 1/4-point offset. In test no. USPBN-3, the car was 

captured by the bullnose with little roll or pitch. As shown in Enclosure 2, maximum occupant 

impact velocity was 33.6 feet/s (10.2 m/s) and the ridedown acceleration was 7.7 g's. The vehicle 

was brought to a stop approximately 21 ft from the first impact point.

Test 3-31 was run as test no. USPBN-4 and consisted of a 4429-lb (2009-kg) pickup truck 

impacting the Bullnose Attenuator head-on at 64.5 mph (103.7 km/h). The truck was captured by the 

barrier and brought to a stop in approximately 51 feet. Occupant Impact Velocity (OIV) was reported 

to be 21.8 feet/s (6.6 m/s) and the maximum acceleration was under 8 g's. Enclosure 3 is the 

summary sheet for this test.

Test 3-38 also required a 100 km/h 2000-kg pickup truck test, but into the side of the Bullnose 

Attenuator at its critical impact point (CIP). The Midwest Roadside Safety Facility test number 

USPBN-2 reported a 2029-kg (4472-lb) truck struck the barrier at 101.3 km/h (62.9 km/h) and 21.7 

degrees. The OIV was 8.6 m/sec (longitudinal) and the Ridedown Acceleration was approximately 

15 g's. Vehicular roll, pitch and yaw were recorded as 12.6, 5.9, and 20.7 degrees, respectively. The 

truck came to rest within the bullnose envelope, 28 feet (8.7 m) downstream from the initial impact 

point. Enclosure 4 is the summary sheet for this test.

Findings

The Thrie beam Bullnose Attenuator with UBSP as described above is acceptable for use on the 

NHS as a non-gating crash cushion primarily used to shield rigid objects located in the medians of 

divided highways. 
3

The conditions listed in the original acceptance letter remain in effect and are repeated here for 

ready reference:

• The leading edge of the bullnose should be installed a minimum distance of 19 m in 

advance of any shielded object or hazard.

• If transitioned to a bridge railing or parapet, the transition should begin no sooner than post 9, 

measured from the nose of the installation

• If an asymmetrical design is used (refer to CC-68 for details), the barrier flare rates on the 

approaching traffic side should not exceed the AASHTO Roadside Design Guide 

recommendations

• The bullnose attenuator should be installed on relatively flat ground (e.g. 10H:1V or 

flatter) to ensure optimal crash performance.

Please note the following standard provisions that generally apply to all FHWA letters of 

acceptance:

• This acceptance letter includes an AASHTO/ARTBA/AGC Task Force 13 designator that 

should be used when creating a new or revised Task Force 13 drawing.

• This acceptance is limited to the crash worthiness characteristics of the systems and does not 

cover their structural features, nor conformity with the Manual on Uniform Traffic Control 

Devices (when applicable).

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

new acceptance letter.

• Should the FHWA discover that the qualification testing was flawed, that in-service 

performance reveals unacceptable safety problems, or that the system being marketed is 

significantly different from the version that was crash tested, we reserve the right to modify 

or revoke our acceptance.

• 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 acceptance, 

and that it will meet the crashworthiness requirements of the FHWA and NCHRP Report 

350.

• To prevent misunderstanding by others, this letter of acceptance is designated as number CC68 A 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 Thrie beam Bullnose Attenuator is not a patented product, nor is it considered 

proprietary. However, if any proprietary devices are specified by a 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. 
4

• This acceptance letter shall not be construed as authorization or consent by the FHWA to use, 

manufacture, or sell any patented system for which the applicant is not the patent holder. 

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 

Enclosures