LS -y 

USDeparrment 

of Tmnsportath 

FedemlHighway 

Administmlion 

JAN24 1990 

REFER TO: 

HNG-14 

Mr. Robert A. Sik 

Vice President, Permanent Mold Division 

Akron Foundry Company 

2728 Wingate Avenue 

P.O. Box 27028 

Akron, Ohio 44319-0009 

Dear Mr. Sik: 

Your June 14, 1989, letter to Mr. David K. Phillips "former Director of Office 

of Engineering" requesting acceptance by the Federal Highway Administration 

(FHWA) of your company's TB-2 and TB-3 series luminaire support transformer 

bases for use on Federal-aid highway projects was not acted on because you 

requested'that we suspend our review. Recently you requested that we complete 

our review, which we have done. With your June 14 letter you enclosed four 

Southwest Research Institute reports (Project No. 06-2128-107), dated 

May 1989, containing results of pendulum tests on the bases. The tests were 

conducted to assess the compliance of these bases with FHWA requirements, 

which cite Section 7 of the 1985 American Association of State Highway and 

Transportation Officials' (AASHTO) Standard Specifications for Structural 

Supports for Highway Signs, Luminaires and Traffic Signals. 

The tests used an instrumented 1,800-pound pendulum fitted with a 10 stage 

crushable nose which simulates the left quarter point of a 1979 Volkswagen 

Rabbit. Details of the tested hardware and the measured and extrapolated 

results are suaanarized in the enclosed table. That information shows that the 

actual tests and calculated changes in velocity of the pole-base combinations 

shown in the enclosure meet the change in velocity and stub-height 

requirements adopted by the FHWA. Nominally, the 16.3 f.p.s. calculated 

change in velocity of test AF-3 exceeds FHWA requirements by 0.3 f.p.s. 

However, we believe the calculated changes in velocities nearly always over 

estimate the 60 m.p.h. results and that the accuracy of the testing and 

extrapolation procedure does not justify the precision reported. Thus, we 

have rounded the reported value to 16 f.p.s., which is the upper limit of 

acceptability under the new FHWA requirements. Inaddition, the test of the 

TB2 base (Test AF-1) used a bottom bolt circle diameter of 10.5 inches, 

whereas the hardware can acconanodate a bolt circle of up to 12 inches. Until 

further testing of the TB2 base confirms satisfactory breakaway performance 

with the larger bottom bolt circle, its use should be limited to installations 

with a bolt circle no greater than 10.5 inches. 

Thus, the T82 bases with bottom.bolt circle diameters up to 10.5 inches, and 

the TB3 bases, as shown on the enclosed drawings, are acceptable for use on 

Federal-aid highway projects, when used with poles weighing no more than those 

used in their respective qualifying tests, if proposed by a State. This 

acceptance is limited to breakaway characteristics of the bases and does not 

cover their 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 the Akron Foundry Company that the castings furnished have

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

castings used in the tests, and that the castings will meet the FliWA change in

velocity requirements.

Sincerely yours,

L. A. Staron

Chief, Federal-Aid and Design Division

Enclosures
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: Base ! Base

Test Base ’ Test Calc'd Stub Pole I Pole

Number Number I Delta V Delta V Height Weight !

Nominal Mast

Type Luminaire Arm i "% "%? K@

Bottom ; Top

Washer . Bolt BX% WaTZr WaTzr

! @ Zhph @ COmph (in.) W/arm & !

: (fps) (fps) Dummy !

fbunting Length ! Circle Diameter Outside Thick- ! Circle Diameter Outside ThickHeight (ft) !Diameter (in.) Diameter ness

: (pounds) : (feet) ! (in.) (in.)

!Dirt;r

(in.) ! n.

(in.) Di;t;r ness

. (in.1

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;

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AF-1 TBZ-AF 1012 I.W.-17 t

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12.0 494 I steel 40.8 15.0 f 10.5 1.00 2.75 0.50 i

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AF-3 TB3-AF 1517 I.W.-17 ! 10.3 16.3 * 778 ! steel 50.0 15.0 : 17.25 1.25 2.75 0.50 !

AF_4 TB3& 1517 I.W._17 . ’ 6.4 15.0 * 778 . I steel 5DD . 1Cn 13." : 15 l.DD 2*75** D.375'"!

: ! ! !

I.W. SIGNIFIES INTERNAL WELD ! ! :

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13 1.25

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