Refer to: HNG-14

Mr. Joseph J. Brindlinger

Manager Engineering Services

Union Metal Corporation

P.O. Box 9920

Canton, Ohio 44711

Dear Mr. Brindlinger:

Thank you for your letter of March 1 to Mr. Thomas 0. Willett requesting

the Federal Highway Administration's (FHWA) acceptance for your company's

transformer base shown on the enclosed drawing, (drawing A2850-Cl,

revision 10, dated l-10-90). You enclosed the Pendulum Test Report No. UMC-B

by the Southwest Research Institute (SWRI) which detailed the test article and

impact results for the 20 mph test. A 20 to 60 mph extrapolation of the

velocity change was also included. Your subsequent letter of March 26

responded to our telephone request for information on the stub height and the

aluminum alloy used in the castings.

The test used an instrumented 1,800-pound pendulum fitted with a IO-stage

crushable nose, which simulates a 1979 Volkswagen Rabbit. The results are

summarized below:

Test speed

Velocity change

Stub height (actual)*

Base tested**

20 mph

6.9 fps

6.4 in.

A2850-C1R1O 12.5-inch bottom bolt circle.

Nuts torqued to 200 foot-pounds.

Pole used

Mast arm lengths

111-9.0” x 4.82” x 41’9” steel.

15 feet, (two mounted perpendicular to the

direction of impact.)

Luminafre mounting height 50 feet

Test article weight 810 pounds

Calculated 60 mph velocity 11.9 fps

change

*The reported stub height was 2.4 inches, which is the measurement to

the top of the anchor bolt. A shard of aluminum from the transformer

base remained in place to a height of 6.4 inches. We concur with the

SWRI conclusion that the protrusion above the 4-inch maximum does not

constitute "substantial remains" as referred. to in Section 7 of the

AASHTO Standard Specifications for Structural Supports for Highway

Signs, Luminaires and Traffic Signals.
**The tested base was cast using a special aluminum

The specified mechanical properties are as follow:

tensile, 17.0 ksi minimum yield, and 0.5 percent to

elongation.

2

alloy, 356.0-T55.

25.0 ksi minimum

3 percent'

This information shows that the actual test and calculated change in velocity

of the subject pole-base combination meet the change in velocity and stubheight requirements adopted by the FHWA.

Thus, this base, with a bottom bolt circle diameter of u 12.5 inches and

maximum bolt torque of 200 foot-pounds, as shown on the enclosed drawing, is

acceptable for use on Federal-aid highway projects, if proposed by a State

when used with poles weighing up to 900 pounds. The use of this base with

heavier poles is unacceptable without further justification. This acceptance

is limited to breakaway characteristics of the base and does not cover its

structural features. Presumably, you will supply potential users with

sufficient information on structural design and installation requirements to

ensure proper performance. We anticipate that the States will require

certification from Union Metal Corporation that the bases furnished have

essentially the same chemistry, mechanical properties, and geometry as the

base used in the tests, and that the bases will meet the FHWA change in

velocity requirements.

Since your company's transformer base design is a proprietary item, to be used

in a Federal-aid highway project it; (a) must be supplied through competitive

bidding with equally suitable unpatented items; (b) the State highway agency

must certify that it is essential for synchronization with existing highway

facilities, or that no equally suitable alternate exists; or (c) it 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, a copy of which is enclosed for your information.

Sincerely yours,

Enclosures

L. A. Staron

Chief, Federal-Aid and Design Division

Geometric and Roadside Design Branch acceptance letter number LS-11
‘Z&Z

- OUAI. D:MS.

ORE D’Y’S fOR PI’r: CONllRlY

! NOT FOR IN5PLC:IOIJ 01‘WQU

CASTINGS.

. . ..m.*..n-. . ..

“.rw”. _...L

_-. _.

. -~----. . _-I- I, l . 

-