us Deportment

of TransportatiOn

Federal Highway

Administration

Ronald K. Faller, Ph.D., P.E.

Midwest Roadside Safety Facility

University ofNebraska, Linco ln

527 Nebraska Hall

P.O. Box 880529

Lincoln, Nebraska 68588-0529

Dear Dr. Faller:

April 6, 2006 400 Seventh St., S.W.

Washington, D.C. 20590

In Rep ly Refe r To:

HSA-I OIB-145

-

Thank: you for your letter ofDecember 16, 2005. requesting the Federal Highway

Administration (FHWA) acceptance ofa Test Level 5 (TL- 5) Bridge Rail developed in

cooperation with the Nebraska Department of Roads. Accompanying your letter were reports

ofcrash testing you conducted at the Midwest Roadside Safety Facility along with video and

photographic documentation of the tests. You requested that we find this railing acceptable for

use on the National Highway System (NHS) under the provisions ofthe National Cooperative

Highway Research Program (NCHRP) Report 350 "Recommended Procedures for the Safely

Performance Evaluation ofHighway Features:'

Introduction

The FHWA guidance on crash testing ofroadsidc sa fety hardware is contained in a

memorandum dated July 25, 1997, lilled "INFORMATION: Identifying Acceptable Highway

Safety Features."

A briefdescription ofthe barrier follows:

The 121·ft 6-in.long, aesthetic post and beam concrete brid ge rail con sisted of a "ribbed"

reinforced concrete beam 14-in. wide by 3D-in. deep with a 42-in. top mounting height which

was cast in place with a 2-in. overhang on the front face ofthe posts parallel to the roadway

and flush with the backside ofthe posts. The two " ribs" extend in. from the face of the

beam. Both upstream and downstream edges o f the posts were tapered back 2 in. from the face

ofthe post to minimize tire snagging ofpassengcr vehicles. Fifteen brid ge posts, measuring

1O.5-in. wide by 3D-in. long by tz-in. high. were used to support the bridge rail. Bridge posts

were spaced 8 ft - 6 in. on centers along the length of the bridge railing. The concrete used for

the brid ge rail and posts had a minimum compressive strength of 5.000 psi.
2

A minimum concrete cover 0£2 in. was used for all the rebar placed within the bridge rail and

posts. All steel reinforcement in the bridge rail and posts was Grade 60 epoxy-coated rebar.

The bridge rail and post dimensions. including reinforcement details. arc shown in the enclosed

drawings for reference.

Testin g

Full-scale tractor-semi trailer testing was conducted on the barrier. The report explai ns that

concrete barriers with similar features have been successfully crash tested with S20e and

2000P vehicles. We concur that the single TL-5 test is the only one requ ired to qualify this

barrier.

The test is summarized in the table below.

NCllRP Report 350 Test 5· 12

Reoort Number TRP 03·1 48·05

Mass of Test Veh icle 35,822 kg (78,975 pounds)

Impact Speed 79.6 kmIh 149.4 mph)

my Longitudinal 0.91 mls (2.99 ft/s)

my Lateral 5.50 mls II 8.05 ft/s)

Ridedown Lon gitudinal 8.05 g's 1-6.98 g's

Ridedown Lateral 6.06 z's 1-7.91 a 's

Dvnamic Deflection 285 mm II 1.2 in.)

Working Width 1916 mm(75.4 in.)

Findings

The test showed that the aesthetic open concrete bridgerail adequately contain ed and redirected

the vehicle with controlled lateral displacements of the rail. There we re no detached elements

or fragmen ts which showed potential for penetrating the occupant compartment nor presented

undu e hazard to other tra ffic. There were no deformations or intrusions into the passenger

compartment that cou ld have caused serious injury. The test vehicle did not penetrate or roll

over the barri er, and it remained upright without intruding into adjacent traffic lanes. Veh icle

roll, pitch, and yaw we re good to moderate. As shown above, while the dynamic deflection

was about 11 in., the Work ing Width (deflection plus vehicle overhang plus width ofthe rail

system) was slightly over 6 ft.

The resu lts ofthe testing met the J\CHRP Report 350 requirements and, therefore, the device

desc ribed above and detailed in the enclosed drawings is acceptable for use on the 1\,1-I.S as a

TL-5 bridge rail, under the range ofconditions tested, when proposed by a State.

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

• Our acceptance is limited to the crashworthiness characteristics ofthe barrier.

• Any changes that may adversely influence the crashworthincss ofthe device will require

a new acceptance letter.
3

• Should the FHWA discover that the qualification testing was flawed. that in-service

performance reveals unacceptable safety problems, or that the device being mark eted is

signi ficantly ditTerent from the version that was crash tested, it reserves the right to

modify or revoke its acceptance.

• You will be expected to supply potential users with sufficient information on design and

installation requirements to ensure proper performance.

• Users will be expected to ensure that the materials in the constructed barrier have

essentially the same chemistry, mec han ical properties, and geome try as that submitted for

acceptance, and that the design will meet the crashworthiness requirements ofthe FHWA

and the NCHRP Report 350.

• To prevent misunderstanding by others , this letter of acceptance, designated as number

8 -145 shall not be reproduced except in full. This letter, and the test documentation upon

which this letter is based, is 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 device for which the applicant is not the patent

holder. The acceptance letter is limited to the crashworthiness characteristics ofthe

candidate device, and the FHWA is neither prepared nor requ ired to become involved in

issues concern ing patent law. Patent issues, if any, are to be resolved by the app licant.

Sincerely yours,

Director

~~~ , Oflic e ofSafety Design

Office ofSafety

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Figure 9, Layout for NDOR', TL-S Aesthetic Open Concrete Bridge Rail
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NOTES:

( 1) USE CRADE 60 O:POXY- COATED REINfORCING STEEL

(2) USE 4780 CONCRETE MIX OESIGN WITH 34,. 7 t.lPo l,IlNllolUt.I

28 -OAY CONCRETE COt.lPRESSIY( STRENCTH

(3) USE 610mm IoI INIIotUIol BAA lAP FOR ALl. LONCfT1JOtNAL AND TRANSVERSE

BAAS

(4) USE 51mm CONCRETE COVER FOR AU. CONSTRUCTION EXCEPT fOR

aortoa or BRIDGE DEC!< BETWEEN GRADE BEAM ANO £XISTING

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