1200 New Jersey Ave., SE

 Washington, D.C. 20590

December 19, 2011

FHWA: HSST: WLongstreet: ms: x60087:12/7/11

Revised: sf:x62288:12/19/11

File: h://directory folder/HSST/ B-228 MASH TL-3.docx

 

In Reply Refer To:

HSST/ B-228

Mrs. Karla A. Lechtenberg

Midwest Roadside Safety Facility

130 Whittier Research Center

P. O. Box 830853

Lincoln, NE 68583-0853

Dear Mrs. Lechtenberg:

This letter is in response to your request for the Federal Highway Administration (FHWA) to 

review a roadside safety system for eligibility for reimbursement under the Federal-aid highway 

program.

Name of system: 31-inch (787-millimeter) Midwest Guardrail

System (MGS) Bridge Rail

Type of system: Permanent Bridge Barrier

Test Level: AASHTO Manual for Assessing Safety Hardware, TL-3

Testing conducted by: Midwest Roadside Safety Facility 

Date of request: July 20, 2011

Task Force 13 Designator: SBW04c

Based on a review of crash test results submitted by the manufacturer certifying the device 

described herein meets the crashworthiness criteria of the American Association of State 

Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware 

(MASH), the device is eligible for reimbursement under the Federal-aid highway program. 

Eligibility for reimbursement under the Federal-aid highway program does not establish approval 

or endorsement by FHWA for any particular purpose or use.

The FHWA, the Department of Transportation, and the United States Government do not 

endorse products or services and the issuance of a reimbursement eligibility letter is not an 

endorsement of any product or service

Decision

The following device is eligible, with details provided below:

• 31-inch (787-millimeter) Midwest Guardrail System (MGS) Bridge Rail

Requirements

Roadside safety devices should meet the guidelines contained in the American Association of 

State Highway and Transportation Officials’ Manual for Assessing Safety Hardware (MASH). 
2

The FHWA Memorandum “Identifying Acceptable Highway Safety Features” of July 25, 1997 

provides further guidance on crash testing requirements of longitudinal barriers.

Description

The test installation consisted of 68 feet 9 inches (21.0 meters) of bridge rail installed between 

two approach sections of MGS measuring 50 feet (15.2 meters) and 56 feet 3 inches (17.1 

meters) in length, for a total system length of 175 feet (53.3 meters). Standard 12-gauge (2.66 

millimeters thick) W-beam guardrail was used throughout, and no approach guardrail transition 

sections were used at the guardrail-to bridge rail interfaces. All lap-splice connections in the Wbeam rail were configured to reduce vehicle snag at the splice during the test. 

The MGS was constructed in two sections with a total of seventeen guardrail posts. Post nos. 3 

through 8 and 32 through 38 were galvanized ASTM A36 steel W6x8.5 (W152x12.6) sections 

measuring 72 inches (1,829 millimeters) long, as shown in Figures 86 through 88. Post nos. 1, 2, 

39, and 40 were timber posts measuring 51⁄2 inches wide x 71⁄2 inches deep x 46 inches long (140 

millimeters x 191millimeters x 1,168 millimeters) and were placed in 72 inches (1,829 

millimeters) long steel foundation tubes. The timber posts and foundation tubes are used on 

many tangent guardrail terminals. Post nos. 1 through 8 and 32 through 40 were spaced 75 inches 

(1,905 millimeters) on center with a soil embedment depth of 40 inches (1,016 millimeters). The 

posts were placed in a compacted, coarse, crushed limestone material that met Grading B of 

AASHTO M147-65 (1990) as described in MASH. For post nos. 3 through 8 and 32 through 38, 

6 inches wide x 12 inches deep x 141⁄4 inches long (152 millimeters x 305 millimeters x 362 

millimeters) wood spacer blockouts were used to block the rail away from the front face of the 

steel posts.

Standard 12-gauge (2.66 millimeters thick) W-beam rails with post bolt slots at 75 inches (1,905 

millimeters) intervals were placed between post nos. 1 through 8 and 32 through 40. The 

W-beam’s top rail height was 31 inches (787 millimeters), with a 247⁄8 inches (632 millimeters) 

center mounting height. Rail splices were located at the center of the guardrail span locations.

The bridge rail was constructed with twenty-three guardrail posts. Post nos. 9 through 31 were

ASTM A36 steel S3x5.7 (S76x8.5) sections measuring 44 inches (1,118 millimeters) long. Post 

nos. 9 through 31 were spaced 371⁄2 inches (953 millimeter) on center and mounted in steel 

socket assemblies. A steel bolt was passed through the web of the post and both sides of the 

socket to support the bridge rail and posts. The sockets were anchored to the deck with a 

through-deck bolt that passed through the upper strap of the socket and a lower angle plate which 

was bolted to the socket.

Standard 12-gauge (2.66 millimeters thick) W-beam rails with post bolt slots at 371⁄2 inches (953 

millimeters) intervals were placed between post nos. 9 through 31. The W-beam’s top rail height 

was 31 inches (787 millimeters), with a 247⁄8 inches (632 millimeters) center mounting height. 

Rail splices were located at bridge rail post locations. No blockouts were used with the bridge 

rail, and 6 inches (152 millimeters) long, 12-gauge (2.66 millimeters thick) W-beam backup 

plates were positioned between the bridge rail and bridge posts at both splice and non-splice 

locations. The rail was connected to the posts with 5⁄16-inch (7.9 millimeters) diameter ASTM 

A307 Grade A bolts and nuts and 13⁄4 inches x 13⁄4 inches x 1⁄8 inches (44 millimeters x 44 

millimeters x3.2 millimeters) square washers that were positioned on the traffic-side face of the 
3

bridge rail. A 75 feet long x 4 feet wide x 8 inches thick (22.86 meters x 1.22 meters x 203 

millimeters) concrete bridge deck was designed and built for crash testing the bridge rail.

The thickness of the bridge deck was increased to 12 in. (305 mm) for a width of 12 in. 

(305 millimeters) adjacent to the rigid concrete surface and was anchored to the outer vertical 

edge of the rigid pavement. This deck was intended to simulate a slab-on-girder bridge deck. 

Anchorage consisted of bent no. 5 (16 millimeters diameter) upper dowels spaced 9 inches (229 

millimeters) on center that were embedded in epoxy. Additional no. 4 (13 millimeters diameter) 

lower dowels were spaced 18 inches (457 millimeters) on center. All dowels and deck 

reinforcement were comprised of ASTM A615 steel.

The concrete deck was designed according to the Nebraska Department of Roads (NDOR) 

Bridge Operations, Policies, and Procedures Manual and the empirical design guidelines 

presented in the AASHTO LRFD Bridge Design Specifications. A deck thickness of 8 inches 

(203 millimeters) was used with concrete having a minimum specified 28-day compressive 

strength of 4,000 psi (27.6 MPa). Longitudinal reinforcement consisted of upper no. 4 

(13 millimeters diameter) bars on 12 inches (305 millimeters) centers and lower no. 5 

(16 millimeters diameter) bars on 12 inches (305-millimeters) centers, with the upper

reinforcement offset 6 inches (152 millimeters) from the lower reinforcement. Transverse 

reinforcement consisted of upper no. 4 (13 millimeters diameter) bars on 12 inches 

(305 millimeters) centers and lower no. 5 (16 millimeters diameter) bars on 12 inches 

(305 millimeters) centers, with the upper and lower layers also offset 6 inches (152 millimeters). 

Top concrete clear cover was 21⁄2 inches (64 millimeters), edge concrete clear cover was 2 inches 

(51 millimeters), and bottom concrete clear cover was 1-inch (25 millimeters).

Details of this system are included in this correspondence as an enclosure.

Crash Testing

The barrier was crash tested at the test facilities at the Midwest Roadside Safety Facility. 

Longitudinal barriers, such as W-beam bridge rails, must satisfy the impact safety standards 

provided in MASH in order to be accepted by the Federal Highway Administration (FHWA) for 

use on National Highway System (NHS) new construction projects or as a replacement for 

existing designs not meeting current safety standards. According to TL-3 of MASH, 

longitudinal barrier systems must be subjected to two full-scale vehicle crash tests. The two fullscale crash tests are as follows:

1. Test Designation 3-10 consisting of a 2,425-lb (1,100-kg) passenger car impacting the 

system at a nominal speed and angle of 62 mph (100 km/h) and 25 degrees, respectively.

2. Test Designation 3-11 consisting of a 5,000-lb (2,268-kg) 4-door, half-ton pickup truck 

impacting the system at a nominal speed and angle of 62 mph (100 km/h) and 25 degrees, 

respectively.

Findings

Test no. MGSBR-1 featured a 5,174-lb (2,347-kg) 4-door pickup truck that impacted the barrier 

at a speed of 61.9 mph (99.6 km/h) and at an angle of 24.9 degrees. The bridge rail successfully 

redirected the vehicle while meeting all required safety criteria and sustaining a maximum 
4

deflection of 48.9 inches (1,242 millimeters), compared to 43.9 inches (1,114 millimeters) for 

MGS testing under similar impact conditions. In test no. MGSBR-2, a 2,585-lb (1,173-kg) small 

car impacted the barrier at a speed of 62.3 mph (100.2 km/h) and at an angle of 24.9 degrees. 

The barrier again successfully redirected the vehicle while meeting all required safety criteria 

and sustaining a maximum deflection of 28.0 inches (712 millimeters). This deflection was very 

similar to the 35.9 inches (913 millimeters) deflection measured during testing of the MGS under 

similar impact conditions. Crash Test Summary details of this system are provided as enclosures 

to this correspondence.

Therefore, this system as described is eligible for reimbursement and should be installed under 

the range of conditions tested, when such use is acceptable to a highway agency. Please note the

following standard provisions that apply to the FHWA eligibility letters:

• This letter includes an AASHTO/ARTBA/AGC Task Force 13 designator that should be 

used to identify any new or updated Task Force 13 drawings. 

• This finding of eligibility is limited to the crashworthiness characteristics of the devices 

and does not cover their structural features, or conformity with the Manual on Uniform 

Traffic Control Devices.

• Any changes that may adversely influence the crashworthiness of the device will require 

a new letter.

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

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

significantly different from the version that was crash tested, we reserve the right to 

modify or revoke this letter.

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

installation requirements to ensure proper performance.

• You will be expected to certify to potential users that the hardware furnished has 

essentially the same chemistry, mechanical properties, and geometry as that submitted for 

review, and that it will meet the crashworthiness requirements of the FHWA and the 

AASHTO MASH.

• To prevent misunderstanding by others, this letter is designated as number B-228, and 

shall not be reproduced except in full. This letter and the test documentation upon which 

it is based are public information. All such letters and documentation may be reviewed at 

our office upon request.

• This 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 finding of eligibility is limited to the crashworthiness characteristics of the candidate 

device, and the FHWA is neither prepared nor required to become involved in issues 

concerning patent law. Patent issues, if any, are to be resolved by the applicant.

Sincerely yours,

Michael S. Griffith 
5

Director, Office of Safety Technologies

Office of Safety 

Enclosures