APR 26 1993 

UJO ssvmlm St.. SW. 

wa~hhgton. DC. ZDSSO 

Refer to: HNG-14 

Ray C. Minor, P.E. 

Manager of Engineering 

Hapco Division 

P.O. Box 547 

Abingdon, Virginia 24210 

Dear Mr. Minor: 

Thank you for your March 17 letter to Lawrence A. Staron requesting Federal 

Highway Administration's (FHWA) acceptance of your company's aluminum 

extrusion breakaway bases. Your letter was accompanied by the test report 

dated March 12, 1993, film and video documentation, and confidential 

information regarding material specifications and additional tests performed. 

Additional information and drawings were submitted with your letter of 

April 16. The pendulum testing was conducted to assess the breakaway 

performance of the base with various Hapco aluminum poles. The tests were 

witnessed by Mr. Nicholas Artimovich of this office. Requirements for 

breakaway supports are found in the 1985 American Association of State Highway 

and Transportation Officials (AASHTO) "Standard Specifications for Structural 

Supports for Highway Signs, Luminaires and Traffic Signals." These 

specifications have been adopted, with minor modifications, by the FHWA. 

The breakaway bases, which are shown in the enclosed drawings, are essentially 

slip bases. The bending capacity of the bases comes from the breakaway caps 

that hold the flanges on the ribs attached to the poles to the mating flanges 

on the base lugs. Breakaway comes from an impact force breaking the bolts 

that hold the breakaway caps in place. A friction-reducing tape on the clamp 

faces of the breakaway caps aids in activation of the breakaway mechanism. 
2 

The results of the tests summarized above meet the change in velocity and. stub 

height requirements adopted by AASHTO and FHWA. Therefore, the tested 

extruded aluminum breakaway bases A73089 and A73088, described above, for 

203~ava (a-inch) and 254-m IlO-inch) butt diameter aluminum luminaire 

supports, respectively, with wall 

acceptable for use on Federal-aid 

conditions tested, if proposed by 

intermediate base sizes, provided 

base ends of the pole shafts. 

thicknesses from 4.77 mm to 6.35 mm are 

kid:;; projects, within the range of 

This acceptance also applies to 

appropriate stiffening is included at the 

Our acceptance is limited to the 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 recommend that 

installation instructions stress the need for a plane surface for mounting 

these breakaway bases. Additionally, the material specifications for the 

bolts that hold the breakaway caps in place must ensure that the bolt 

strengths do not exceed that need for proper release. We anticipate that the 

States will require certification from Hapco Division that the hardware 

furnished has essentially the same chemistry, mechanical properties, and 

geometry as that used in the tests and that it will meet the FHWA change in 

velocity requirements. 

Because the Hapco breakaway extruded aluminum bases are proprietary to be used 

in Federal-aid highway 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 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, a copy of which is enclosed. 

Sincerely yours, 

Lawrence A. Staron 

Chief, Federal-Aid and Design Division 

5 Enclosures 

Geometric and Roadside Design Acceptance Letter LS-29 
Pole COD Alloy/ 43 

With S. S. Screws 

21 0" 

8” O.D.- 

Figure (3) 

Hapco Drawing No. 373071, 

30' Lighting Pole 

.125” Wall Alloy 6063- T6 

$,$ 

I 

\ Wire Hole with I’ I.@. 

\ 

Rubber Grommet 

Extruded Pole Plate Alloy 6063-T6 With 

l/2’- 13NC Stainless Steel Hardware 

30’ 

Moun ti 

2” N.P.S. Slipfitter 

--= 

Tapered Alum. Tube 

.188” Wall Alloy 6063-T6 

With Satin Ground finish 

/ 

BASE DflAIL 

1’ 

Height 

14 1,&Y& 

< / 

I I’ Dia. 

Bolt Circle 

i/iew A-A 

Breakaway Base Fabricated 

From Aluminum Extrusions 

!$ &%t~u~ 

Fl~twashers, And Ldckwashers 

Ground Lug Opposite 

Handhole c 

Reinforced Handhale (4.~6”) With 

Cover And Stainless Steel Hex 

Head Screws 

Rigid Steel 

Test Frame 

,_ Breokoway Base (See Detail) 

r WAmuol kIYlmId~klruIIhalILuYa 

._ 

m ncvmlaam -3OVGHllNGPOLf 

cusmbaa 

t No. 3385 

UIU 32.00 _ 0.r~ 03/08,/93 

Dwa# 

B7307'1 

9 -. 
1 l/4’ 

Slotted Holes 

1 I’ Dia. Bolt Circle 

Top View 

3/r x 2” x 6 3/4” Rib 

Spacer Located 3/4” Above 

fop 

I. 

\ -‘Bose Ring 

Bolt Cover Attachment Hole J \ 

(Bolt Cover Not Shown-See Detoio 

\ 

Cop Bolts (Break 

Upon Impact) 

Side Hew Base Lug (See Detail) 

Cap B’lt 

Holes 

BRMWAY C4P 

BASE LUG 

-cap dl 7. 

Bolt Hole 6" 

1 

Bott Hole 

llrl 

BOLT COVER 

10. REVISIONS 

1 Stiffener Defails 

Added 

OATC 

4/g, m awe 

I TITLE 8" EXTRUSION BASE 

I CUSTOMER 
. Figure (15) 

Hapco Drawing No. B73075 

38'-9" Lighting Pole 

-0' Tmss Arm (48489) 

Orientation Of Bcse Fionge, Hondhole, P.rm 

And lmpoc t Direction 

Pole Cop Alloy 43 

W/th S.S. Screws \ 

35 11’ 

10” O.D.- 

Wire Hole With I’ I.D. With Rubber Grommet 

Cost Alum Pole Bonds With l/2”- 13NC 

Stainless Steel Hordwore 

Mounting Height 

Aluminum Tube 

.188’ Wall Alloy 6063-T6 

Sotin Ground Finish 

15’ Dia. 

Bolt Circle 

view A-A 

/ Breokowoy Bose Fobricoted 

From Alum. Extrusions 

(4) l”-8NC Hex Hd. 

/ 

Ground LL~ 

Opposite HJndhole fJ 

Reinfoned tiondhole (4’ x 6”) With 

Cover And Stainless Steel Hex. Hd. 

Screws 

digid Steel 

Test Frome 

-Breakaway Bose (See Detoilj 

! 
t-1 7 l/Z” SQ.1 l/2” Plote Interior 

I Rein fonzing. (4) Pieces 

/ Located l/r From Tube 

ID- 0-D. - 

Alum. Tubing 

Bottom &d (4) Pieces 

Located g From 

Tube Bottom cop tat 

Holes 

.’ 

L 14’ Dio. Bolt CirCe 

19 Dio. Bolt CirCe 

1 l/4’ x 1 3/4’ _ 

slo&ed Holes r - 

Top Hew 

‘.. f 

6” 

I 

Rib Spacer 

1/r x r x 2 3/4” 

Right Rib 

(See D$oil,’ 

Breokowoy Cap 

(See Detail) 

-RIGHT RIB 

Bose Ring 

Bolt Cover Attachment Hole J 

(Bolt Cover Not Shown-See Detail) \ 

Cop Bolts (Break 

Upon impact) 

Side Hew L Bose Lug (See Detoio 

BOLT COWR