1200 New Jersey Ave., SE

Washington, D.C. 20590

May 2, 2011

In Reply Refer To:

HSST/SS-171

Mr. Pratip K. Lahiri, P.E.

Manager, Specifications and Standards Section, POD 23

Design Quality Assurance Bureau

New York State Department of Transportation 

50 Wolf Road 

Albany, New York 12232

Dear Mr. Lahiri:

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

acceptance of a roadside safety system for use on the National Highway System (NHS).

Name of system: Aluminum Pedestrian Signal Pole 

Type of system: Breakaway Support Structure 

Test Level: NCHRP Report 350 TL-3

Testing conducted by: Midwest Roadside Safety facility

Date of request: November 30, 2010

Date completed package received: December 6, 2010

Request initially acknowledged: December 7, 2010

You requested that we find this system 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.” 

Requirements

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

American Association of State Highway and Transportation Officials’ Manual for Assessing 

Safety Hardware (MASH). Requirements for breakaway supports are those in the American 

Association of State Highway and Transportation Officials’ (AASHTO) Standard Specifications 

for Structural Supports for Highway Signs, Luminaries, and Traffic Signals. 

Decision

The following device was found acceptable:

• New York State DOT Aluminum Pedestrian Signal Pole 
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Description

The aluminum pedestrian signal pole includes an aluminum pole and a pedestrian “hand/man” 

signal. The aluminum pole is attached to a rigid foundation by a frangible aluminum base plate 

and four bolts.

The pole is a 10 ft (3.1 m) tall, round aluminum pole with a 1/8 inch (3 mm) wall thickness. The 

pole has a top outside diameter of 41⁄2 inches (114 mm) and a bottom outside diameter of 6 

inches (152 mm). A 5/32 inch (4 mm) thick, 24 inches (610 mm) tall internal reinforcing sleeve 

is located at the bottom of the pole and serves to strengthen the base of the pole against 

premature yielding during an impact. A handhole is placed through both the pole and the 

internal sleeve and centered at a height of 18 inch (457 mm). 

The pole base plate is a 101⁄4 inch (260 mm) square with a thickness of 5/8 inch (16 mm). The 

bolt circle is 91⁄2 inches (241 mm) in diameter, and the pole was inserted and welded to a 31⁄2 inch 

(89 mm) tall cylinder, as measured from the bottom of the base plate. Enclosure 1 and Enclosure 

2 illustrate the details of the pole. 

The pedestrian “hand/man” signal conformed to Standard Sheet No. 680-10 used by New York 

State DOT. The signal is mounted to the pole using a top-mounted attachment bracket, as shown 

in Enclosure 3. The signal is attached to the bracket by inserting the top, threaded portion of the 

bracket into the hole at the bottom of the signal. The combined weight of the signal and bracket 

was 26 lb (12 kg). After attachment to the pole, the total system weighed 59 lb (27 kg). 

Crash Testing

A pendulum testing was conducted on the test articles described above by Midwest Roadside 

Safety facility. The pendulum test was conducted according to NCHRP 350 test designation 3-

60 as a surrogate for a full crash test with an 820C car. 

Findings

According to NCHRP 350, test designation 3-60 and test designation 3-61 are to be conducted 

for support structures for Test Level 3 acceptance. In both tests full scale automobile testing 

with 820C small car is required. 

In this request, test 3-60 was conducted using a pendulum. The mass of the pendulum was 861 

kg and the pendulum was configured to represent the front-end crush stiffness of a 1979 

Volkswagen Rabbit two-door sedan as a small car.

According to the test results, as reported by the Midwest Roadside Safety facility, the test article 

passed test 3-60 conducted using the pendulum. In this test, maximum vehicle velocity change 

was below the maximum allowable limits of NCHRP 350 (Enclosure 5). In this test, the pole 

broke away from the base plate assembly in a controlled and predictable manner. The signal 

pole fell in front of the surrogate vehicle, neither the signal box nor the fractured pole showed 

any potential for penetrating or causing larger deformations to the occupant compartment. 

The test articles were not crash tested according to test 3-61 (high speed test). However, the 

results of the high speed tests were estimated using the results from the low-speed test in 

combination with an analytical extrapolation method described in FHWA Memorandum HNG-
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14 for Action: Identifying Acceptable Highway Safety Features dated on July 25, 1997. For the 

test article described above, the high speed test extrapolation analysis resulted in change in 

velocity values for the high speed test below the NCHRP 350 limit of 5.0 m/s. Therefore, the 

test article would likely successfully pass the high speed test. 

The AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaries, 

and Traffic Signals require that any “substantial remains” of the breakaway support not project 

greater than 4 inches above ground level to avoid vehicle undercarriage snagging. After the test 

portions of the fractured aluminum base plate assembly projected 41⁄2 inches (114 mm) which 

violates the 4 inch (100 mm) stub height limit. Therefore, the test article does not pass all 

requirements set forth by FHWA. 

In your request letter, you proposed two alternative modifications to the system design in order 

to overcome the issue associated with the remaining stubs:

1. The leveling nuts, which are 1 inch high, will be specified to be embedded in the grout as 

shown in Enclosure 4 (Option 1). This will ensure that the distance from the ground to 

the top of the collar, assuming the same break point, will be less than 4 inches high. 

2. The concrete foundation used for the system will be specified to be level with the 

surrounding ground and any sidewalk. In addition, in order to ensure that the maximum 

height to the top of the collar from the foundation does not exceed 4 inches, two 

alternatives can be implemented:

a. The existing collar height is kept (3 1⁄2 inches) and shims (Enclosure 5) are used to 

level the pole instead of nuts; or

b. The height of the collar is reduced to 3 inches and 1 inch or 7/8 inch high leveling 

nuts are used. 

I concur in either of the proposed modifications on the grounds that they can ensure that the 

remaining stubs will not exceed the 4 inch limit. 

Therefore, the system described in the requests above and detailed in the enclosed drawings is 

acceptable for use on the NHS under the range of conditions tested, when such use is acceptable

to a highway agency.

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

• This acceptance is limited to the crashworthiness characteristics of the systems and does 

not cover their structural features, nor conformity with the Manual on Uniform Traffic 

Control Devices.

• 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.
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• 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 verify that hardware installed 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 

SS-171 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.

• 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