ieel: ACTION: Wyoming Road Closure Gate 

rim: Chief, Federal-Aid and Design Division 

Reply 10 

fun. 01: HNG-14 ’ 

TO: Mr. Vincent F. Sch,immoller 

Regional Federal Highway Administrator (HRA-08) 

Lakewood, Colorado 

This is in response to your January 20 memorandum r#equesting Federal Highway 

Administration's (,FHWA) acceptance,of the Wyoming Road Closure Gate as meeting 

breakaway requirements for use on the National Highway System; Transmitted 

with your memorandum were a video tape and report of tests on the Road Closure 

Gate conducted at the Texas Transportation Institute. The report is dated 

February 1994. The gate arm is mounted on a four-bolt slip-base luminaire 

support that was the'subject of a crash test report dated August 1991, that_ 

you also enclosed. The gate arm is mounted at a height of 1.2 m. A drawing 

of the Road Closure Gate is attached. 

Full-scale crash testing was conducted to assess the breakaway performance ,of 

the subject device mounted on a rigid concrete foundation. Requirements for 

breakaway supports are found in the American Association offState Hlghwa: and 

'iSransportaft;rr+Officials' (AASHTO) Standard Soecifications or Structura 

Moorts o ahwav Sians. Lumlnai s and Traffic S'a als These 

specifications have been adopted by?he FHWA. Guide;i:es established in the 

National Cooperative.Highway Research Program Report 350 were followed in 

conducting the tests and analyzing their results. 

A sumnary of the crash test is presented below: 
2 

Then four 25.4~mm high strength steel slip bolts were torqued to 4.8 N-m 

and were held in place with a 28 gage keeper plate; The bolt circle 

diameter was 330 n. 

*The extensive occupant compartment intrusion resulted in this test being 

called a failure. The system was retested with a taller and more massive 

luminaire support. The increased height of the center of gravity of the 

system in tests 472280-2 and -3 permitted the test vehicle to travel 

beyond the hazard before significant contact was made by the pole. 

The results of Tests 477280-2 and -3 meet the change-in-velocity+ -stub-height, 

and occupant: compartment integrity requirements adopted by the FHWA. The 

Wyoming Road Closure Gate on an 8.8-m high luminaire support as shown in the 

drawing, is therefore acceptable for use on the National Highway System, 

within the range of conditions tested, if proposed by a State. 

Our acceptance is limited to the breakaway c,haracteristics of the slip-base 

mechanism and does not cover.the structural features. Presumably the State 

~~111 develop sufficient information on structural design and installation 

requirements to ensure proper performance. 

Attachment 

V 

Geometric and Roadside Design Acceptance LetterNo. LS-36 
27’~6 

(1 r-b th.) 

Gate Arm Pbte 7 

\ iS Channel spacer --j 

L 

I 

. 

t 

I Y-5 3/c 

---.-_/-’ /-- 

Figure i. Sihematic of road closuxye gate (arm down) as tested. 

3’ 

f 

5- Channel SPOCW 

- 1 l/Z- Dia. Hole 

Electric In-Line 

Linear Actuator 

Bottom Cawwctkn 

&sembly 
l/2” Thick Plate Washers 

- 3 Raouired ner Cnnn. 

..--I-..-- I--. 

Eolt.- (See Detail) 

-_..... 

Weld Size Equal to 

Shaft Wall Thickness 

4-1” Dia. ASTM A325 Slip Bolts 

w/ Heavy Hex Nuts and Standard Washers 

Top Plate (See Detail) 

28 Gage Slip Bolt Gasket (See Detail) 

Slip Base Assembly (See Detail) 

3/8” Dia. j Drain Pipe 

4-1” Dia. Anchor Bolt 

Galvanized Sheet Metal Sleeve 

Galvinized Sheet Metal to Keep 

Grout From Slip Bolts 

BREAKAWAY BASE ’