1200 New Jersey Ave., SE

 Washington, D.C. 20590

August 18, 2011

FHWA:HSSI:NArtimovichr:ms:x61331:7/14/11

File: s://directory folder/HSST/Artimovich/LS75_Valmont #12.dotx

cc: HSST (NArtimovich; JDewar) 

In Reply Refer To:

HSST/LS-75

Mr. Zach Thiemann, E.I.T.

Associate Product Development Engineer

Valmont Industries, Inc. 

7002 North 288th Street/P.O. Box 358

Valley, Nebraska 68064-0358

Dear Mr. Thiemann:

This letter is in response to your request for the Federal Highway Administration (FHWA) 

acceptance of specific Valmont pole and decorative base covers for use on the National Highway 

System (NHS).

Name of system: Various cast aluminum base covers for lighting and luminaire support posts as 

described below

Type of system: Valmont Decorative “Clamshell” Covers for Various Lighting Poles and 

Luminaire Supports

Test Level: NCHRP Report 350 Test Level 3 (Pendulum Testing)

Testing conducted by: Midwest Roadside Safety Facility (MwRSF)

Date of requests: December 30, 2010

Request initially acknowledged: January 5, 2011

You requested that we find five (5) decorative base covers used with a range of previouslyaccepted breakaway couplings and with a range of aluminum poles acceptable for use on the 

NHS under the provisions of the National Cooperative Highway Research Program (NCHRP) 

Report 350 “Recommended Procedures for the Safety Performance Evaluation of Highway 

Features.” The specific clamshell bases for which acceptance is requested include the Memphis, 

Washington, Huntington, Harrisburg, and Osceola designs.

Requirements

Roadside safety devices should meet the guidelines contained in the National Cooperative

Highway Research Program (NCHRP) Report 350 if tested prior to December 31, 2010, and the 

American Association of State Highway and Transportation Officials’ (AASHTO) Manual for 

Assessing Safety Hardware (MASH) if tested after that date. Requirements for breakaway 

supports are contained in the AASHTO Standard Specifications for Structural Supports for 

Highway Signs, Luminaires, and Traffic Signals.

Decision
2

The Valmont clamshell designs/pole configurations described below were tested by the MwRSF 

and found to meet the required evaluation criteria. 

Test Descriptions

A test protocol was developed to test the crashworthiness of two “worst case” combinations of 

clamshell bases and aluminum poles mounted on breakaway couplings. The largest clamshell 

base was tested on a 55-foot (16.8-meter) tall aluminum pole/luminaire arm assembly using

TRANSPO Industry’s 1.25-inch (32-millimeter) diameter double-neck, pole-safe breakaway 

couplings. In addition, the heaviest clamshell base that could fit around an 8-foot (2.4-meter) tall 

aluminum pole without a top attachment was tested, also utilizing TRANSPO breakaway 

couplings. The clamshell bases suffered only minor to moderate damage, and the calculated 

changes in velocity (ΔVs) for the surrogate vehicle in each test satisfied the 16.4 ft/s (5.0 m/s) 

limit. The results for NCHRP Report 350 test designation 3-61 were conservatively estimated 

using the high-speed test extrapolation equation, and all three tested configurations provided ΔVs 

below the 16.4 ft/s (5.0 m/s) limit. Each of the three tests that were conducted is described in 

more detail below. 

In test LST-440, the 1,842-pound (836-kilogram) pendulum impacted an 8-foot (2.4-meter) 

nominal height aluminum pole fitted with your Memphis decorative clamshell base (Enclosure 1) 

at a speed of 21.5 mph (34.7 km/h). In this test, the welds between the pole and the base plate 

fractured instead of the TRANSPO couplings. Consequently, the base plate and couplings 

remained attached to the foundation after the initial impact leaving a stub height of 97⁄8 inches

(251 millimeters), exceeding the 4-inch (100-millimeter) height limit. Therefore, this test was 

repeated as test LST-455 after a sweeper plate was added to the pendulum. Enclosure 2 is a

summary of the test results for LST-440.

In test LST-441, the pendulum impacted a 55-foot (16.8-meter) nominal height aluminum pole 

and your Washington decorative clamshell base (Enclosure 3) at a speed of 21.8 mph (35.1

km/h). All four couplings fractured at the lower neck location leaving a stub height of 3 inches

(76 millimeter) which falls below the 4-inch (100-millimeter) limit. Enclosure 4 is a summary of 

these test results.

Test LST-455 was a repeat of test LST-440. With the addition of the aforementioned sweeper 

plate to the pendulum, the TRANSPO couplers fractured at their lower necks, leaving a stub 

height of only 3 inches (76 millimeters). Enclosure 5 is a summary of test LST-455.

Crash Testing

Pendulum testing was conducted on the test articles described above by the MwRSF at 

Valmont’s pendulum facility in Valley, Nebraska. All tests were conducted according to 

NCHRP 350 test designation 3-60. The FHWA accepts pendulum tests as surrogates for this 

low-speed small car test. The FHWA also allows the results of the high speed tests to be 

estimated using data from the low-speed pendulum test in combination with an analytical 

extrapolation method described in the FHWA memorandum “Identifying Acceptable Highway 

Safety Features” dated on July 25, 1997.

Findings

Based on the test results described above, your Memphis-15 and Washington-30 clamshell bases 

are considered to be crashworthy when used in combination with the breakaway couplings and 
3

pole sizes in tests LST-440 and LST-441. Since testing was conducted using both the shortest 

and lightest pole used with the heaviest base for that pole size and with the largest pole/luminaire 

and heaviest base combination, you requested acceptance of intermediate pole and clamshell 

base combinations. The additional bases were the Huntington (Enclosure 6), the Harrisburg 

(Enclosure 7), and the Osceola (Enclosure 8) designs. In summary, the FHWA concurs that these

five bases are acceptable for use on the NHS when:

• used with Transpo couplings ranging from 0.75-inches (20-millimeters) to 1.25-inches 

(32-millimeters) in diameter 

• used with aluminum poles ranging from 0.125-inches (32-millimeters) to 0.313-inches 

(7.9-millimeters) thick 

• used with aluminum poles with mounting heights ranging from 8 to 55 feet (2.6 to 16.8-

meters)

• used with aluminum poles having base diameters ranging from 4 to 10 inches (102 to 

254-millimeters).

Please note the following standard provisions that apply to FHWA letters of acceptance:

• This acceptance is limited to the crashworthiness characteristics of the tested features and 

does not cover their structural features, such as resistance to wind loads. 

• Any design or material changes that may adversely influence the crashworthiness of the 

Dent 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 the 

NCHRP Report 350.

• To prevent misunderstanding by others, this letter of acceptance is designated as number 

LS-75 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 Valmont poles and decorative clamshell bases identified above are patented products 

and considered proprietary. If proprietary systems 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 acceptance letter is limited to the crashworthiness characteristics of the 

candidate system, and 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 18, 2011

In Reply Refer To:

HSST/LS-75

Mr. Zach Thiemann, E.I.T.

Associate Product Development Engineer

Valmont Industries, Inc. 

7002 North 288th Street/P.O. Box 358

Valley, Nebraska 68064-0358

Dear Mr. Thiemann:

This letter is in response to your request for the Federal Highway Administration (FHWA) 

acceptance of specific Valmont pole and decorative base covers for use on the National Highway 

System (NHS).

Name of system: Various cast aluminum base covers for lighting and luminaire support posts as 

described below

Type of system: Valmont Decorative “Clamshell” Covers for Various Lighting Poles and 

Luminaire Supports

Test Level: NCHRP Report 350 Test Level 3 (Pendulum Testing)

Testing conducted by: Midwest Roadside Safety Facility (MwRSF)

Date of requests: December 30, 2010

Request initially acknowledged: January 5, 2011

You requested that we find five (5) decorative base covers used with a range of previouslyaccepted breakaway couplings and with a range of aluminum poles acceptable for use on the 

NHS under the provisions of the National Cooperative Highway Research Program (NCHRP) 

Report 350 “Recommended Procedures for the Safety Performance Evaluation of Highway 

Features.” The specific clamshell bases for which acceptance is requested include the Memphis, 

Washington, Huntington, Harrisburg, and Osceola designs.

Requirements

Roadside safety devices should meet the guidelines contained in the National Cooperative

Highway Research Program (NCHRP) Report 350 if tested prior to December 31, 2010, and the 

American Association of State Highway and Transportation Officials’ (AASHTO) Manual for 

Assessing Safety Hardware (MASH) if tested after that date. Requirements for breakaway 

supports are contained in the AASHTO Standard Specifications for Structural Supports for 

Highway Signs, Luminaires, and Traffic Signals.

Decision
2

The Valmont clamshell designs/pole configurations described below were tested by the MwRSF 

and found to meet the required evaluation criteria. 

Test Descriptions

A test protocol was developed to test the crashworthiness of two “worst case” combinations of 

clamshell bases and aluminum poles mounted on breakaway couplings. The largest clamshell 

base was tested on a 55-foot (16.8-meter) tall aluminum pole/luminaire arm assembly using

TRANSPO Industry’s 1.25-inch (32-millimeter) diameter double-neck, pole-safe breakaway 

couplings. In addition, the heaviest clamshell base that could fit around an 8-foot (2.4-meter) tall 

aluminum pole without a top attachment was tested, also utilizing TRANSPO breakaway 

couplings. The clamshell bases suffered only minor to moderate damage, and the calculated 

changes in velocity (ΔVs) for the surrogate vehicle in each test satisfied the 16.4 ft/s (5.0 m/s) 

limit. The results for NCHRP Report 350 test designation 3-61 were conservatively estimated 

using the high-speed test extrapolation equation, and all three tested configurations provided ΔVs 

below the 16.4 ft/s (5.0 m/s) limit. Each of the three tests that were conducted is described in 

more detail below. 

In test LST-440, the 1,842-pound (836-kilogram) pendulum impacted an 8-foot (2.4-meter) 

nominal height aluminum pole fitted with your Memphis decorative clamshell base (Enclosure 1) 

at a speed of 21.5 mph (34.7 km/h). In this test, the welds between the pole and the base plate 

fractured instead of the TRANSPO couplings. Consequently, the base plate and couplings 

remained attached to the foundation after the initial impact leaving a stub height of 97⁄8 inches

(251 millimeters), exceeding the 4-inch (100-millimeter) height limit. Therefore, this test was 

repeated as test LST-455 after a sweeper plate was added to the pendulum. Enclosure 2 is a

summary of the test results for LST-440.

In test LST-441, the pendulum impacted a 55-foot (16.8-meter) nominal height aluminum pole 

and your Washington decorative clamshell base (Enclosure 3) at a speed of 21.8 mph (35.1

km/h). All four couplings fractured at the lower neck location leaving a stub height of 3 inches

(76 millimeter) which falls below the 4-inch (100-millimeter) limit. Enclosure 4 is a summary of 

these test results.

Test LST-455 was a repeat of test LST-440. With the addition of the aforementioned sweeper 

plate to the pendulum, the TRANSPO couplers fractured at their lower necks, leaving a stub 

height of only 3 inches (76 millimeters). Enclosure 5 is a summary of test LST-455.

Crash Testing

Pendulum testing was conducted on the test articles described above by the MwRSF at 

Valmont’s pendulum facility in Valley, Nebraska. All tests were conducted according to 

NCHRP 350 test designation 3-60. The FHWA accepts pendulum tests as surrogates for this 

low-speed small car test. The FHWA also allows the results of the high speed tests to be 

estimated using data from the low-speed pendulum test in combination with an analytical 

extrapolation method described in the FHWA memorandum “Identifying Acceptable Highway 

Safety Features” dated on July 25, 1997.

Findings

Based on the test results described above, your Memphis-15 and Washington-30 clamshell bases 

are considered to be crashworthy when used in combination with the breakaway couplings and 
3

pole sizes in tests LST-440 and LST-441. Since testing was conducted using both the shortest 

and lightest pole used with the heaviest base for that pole size and with the largest pole/luminaire 

and heaviest base combination, you requested acceptance of intermediate pole and clamshell 

base combinations. The additional bases were the Huntington (Enclosure 6), the Harrisburg 

(Enclosure 7), and the Osceola (Enclosure 8) designs. In summary, the FHWA concurs that these

five bases are acceptable for use on the NHS when:

• used with Transpo couplings ranging from 0.75-inches (20-millimeters) to 1.25-inches 

(32-millimeters) in diameter 

• used with aluminum poles ranging from 0.125-inches (32-millimeters) to 0.313-inches 

(7.9-millimeters) thick 

• used with aluminum poles with mounting heights ranging from 8 to 55 feet (2.6 to 16.8-

meters)

• used with aluminum poles having base diameters ranging from 4 to 10 inches (102 to 

254-millimeters).

Please note the following standard provisions that apply to FHWA letters of acceptance:

• This acceptance is limited to the crashworthiness characteristics of the tested features and 

does not cover their structural features, such as resistance to wind loads. 

• Any design or material changes that may adversely influence the crashworthiness of the 

Dent 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 the 

NCHRP Report 350.

• To prevent misunderstanding by others, this letter of acceptance is designated as number 

LS-75 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 Valmont poles and decorative clamshell bases identified above are patented products 

and considered proprietary. If proprietary systems 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 acceptance letter is limited to the crashworthiness characteristics of the 

candidate system, and 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