1200 New Jersey Ave., SE

 Washington, D.C. 20590

November 17, 2011

FHWA: HSSI: WLongstreet: ms: x60087:10/5/11

File: h: //directory folder/HSST/ B-225_Perm Single Slope Concrete Barrier in 

front of steep slope.docx

cc: HSST Will Longstreet 

In Reply Refer To:

HSST/ B-225

David K. Olson

Design Policy Standards & Research Manager

Washington State Department of Transportation

310 Maple Park Avenue S.E.

Olympia, WA. 98504

Dear Mr. Olson:

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: Single Slope Concrete Barrier placed in front of steep slope

Type of system: Permanent Single Slope Reinforced Concrete Barrier

Test Level: AASHTO Manual for Assessing Safety Hardware (MASH) 

Test Level 3 (TL-3)

Testing conducted by: Texas Transportation Institute (TTI)

Date of Request: April 20, 2011

Drawing Designator: SGR42

You certify that the device described herein meets the crashworthiness criteria of the American 

Association of State Highway and Transportation Association’s (AASHTO) Manual on 

Assessing Safety Hardware (MASH). Based on your testing you asked that we find the device

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 the FHWA for any particular purpose or use. 

Requirements

Roadside safety devices should meet the guidelines contained in the Manual for Accessing 

Safety Hardware. The FHWA Memorandum “ACTION: Identifying Acceptable Highway Safety 

Features” of July 24, 1997, provides further guidance on crash testing requirements of 

longitudinal barriers.

Decision

The following device is eligible, with details provided below:

• Permanent Single Slope Concrete Barrier placed in front of steep slope
2

Description

The test article was comprised of a 100 foot long installation of single-slope concrete

barrier embedded 10 inches in soil. Five 20-foot long barrier segments were connected using the

grouted rebar-grid slot connections to achieve the 100 foot installation length.

The single-slope barrier segments were 42 inches tall, 24 inches wide at the base and

8 inches wide at the top. At each end of the barrier segments, a 3-inch wide, 2-inch deep, and

10.5-inch long slot was cast into the barrier to accommodate the grouted rebar-grid connection.

The concrete reinforcement of the barrier segments was comprised of #4 vertical bars that were

bent to approximately match the profile of the barrier faces and were spaced 12 inches apart

along the length of the barrier. The spacing of the vertical bars was reduced around the slot cast

at each end for the grouted rebar-grid connection. The vertical bars, ten #5 longitudinal bars

were located along the height of the barrier. A 4-inch wide, 2-inch high slot was cast at the

bottom of the segments along their centerline.

The barrier was embedded in crushed limestone road base material that conforms to MASH

standard soil. To embed the barrier to a depth of 2 feet, the native soil adjacent to the testing 

facility’s concrete pavement was excavated. The excavated area was then backfilled with

standard MASH soil and compacted in approximately 6-inch lifts. Once the backfill soil reached

a level of 10 inches below the concrete pavement surface, the barrier was set in place and further

soil was added and compacted in front and back of the barrier. As the soil was backfilled, a

1.5H:1V slope was built into the embankment with the breakpoint located 2 feet from the field 

side of the barrier.

A rebar-grid was then dropped into the slot at each barrier connection location. It was comprised 

of two vertical No. 6 bars that were spaced 10 inches apart, and three longitudinal #8 bars that 

were spaced eight inches apart. With the rebar-grid in place, the connection was grouted using a 

non-shrink grout.

The barrier concrete was specified to have a minimum 28-day compressive strength of 4000 psi. 

The reinforcing steel was specified to be grade 60. The steel material used for manufacturing the 

rebar-grid was also specified to be grade 60. The grout used for making the connection was a 

non-shrink grout which had a minimum compressive strength of 4000 psi. The soil used for 

embedding the barriers was a crushed limestone road base material that conforms to standard 

MASH soil. The moisture content of the soil on the day of the test was 8.5%.

Test article details are included in this correspondence as an enclosure.

Crash Testing

The crash test was evaluated in accordance with the criteria presented in MASH. The 

performance of the barrier is judged on the basis of three factors: structural adequacy, occupant 

risk, and post impact vehicle trajectory. Structural adequacy is judged upon the barrier’s ability to 

contain and redirect the vehicle, or bring the vehicle to a controlled stop in a predictable manner. 

Occupant risk criteria evaluate the potential risk of hazard to occupants in the impacting vehicle, 

and to some extent other traffic, pedestrians, or workers in construction zones, if applicable. 
3

Post impact vehicle trajectory is assessed to determine potential for secondary impact with other 

vehicles or fixed objects, creating further risk of injury to occupants of the impacting vehicle 

and/or risk of injury to occupants in other vehicles. The appropriate safety evaluation criteria 

from table 5.1 of MASH were used to evaluate the crash test report.

According to MASH, two tests are recommended to evaluate longitudinal barriers to test

level three (TL-3) as described below.

MASH Test Designation 3-10: A 2425 lb vehicle impacting the critical impact point (CIP) of 

the length of need section at a speed of 62 mi/h and an angle of 25 degrees.

MASH Test Designation 3-11: A 5000 lb pickup truck impacting the CIP of the length of need 

section at a speed of 62 mi/h and an angle of 25 degrees.

MASH test 3-11 involves a 2270P vehicle weighing 5000 lb ±100 lb and impacting the

barrier at an impact speed of 62.2 mi/h ±2.5 mi/h and an angle of 25 degrees ±1.5 degrees. The

target impact point was 4 ft upstream of the centerline of the joint located between segments 2

and 3. The 2002 Dodge pickup used in the test weighed 4953 lb and the actual impact speed and

angle were 63.1 mi/h and 24.2 degrees, respectively. The actual impact point was 62.0 inches

upstream of the joint between segments 2 and 3.

The 2270P vehicle, traveling at an impact speed of 63.1 mi/h, impacted the single-slope

barrier 62 inches upstream of the joint between segments 2 and 3, at an impact angle of

24.2 degrees. At approximately 0.042 s, the right front tire began to climb the face of the barrier

and the vehicle began to redirect. At 0.169 s, the vehicle was parallel to the barrier and was

traveling at a speed of 58.7 mi/h. At 0.173 s, the right rear of the vehicle contacted the barrier,

and at 0.176 s, the vehicle began to roll clockwise. The right rear corner of the bed of the vehicle

contacted the top of the barrier at 0.616 s, and after that, dust obscured the view in all camera

views. Brakes on the vehicle were applied 1.5 s after impact, and the vehicle came to rest 247 ft

downstream of impact and 10 ft toward traffic lanes.

Based on the results of MASH test 3-11 with the 5000 lb pickup truck, the embedded single 

slope barrier system is expected to behave as a rigid barrier when impacted under MASH test 3-

10 conditions with the smaller 2425 lb passenger car. MASH test 3-10 was successfully 

performed on a rigid F-shape concrete barrier. Previous analysis and testing indicates that Fshape and single-slope barriers have similar impact performance. Therefore, it was concluded 

that test 3-10 on the embedded single-slope barrier system was unnecessary.

Test summary details are included in this correspondence as an enclosure.
4

Findings

The embedded single-slope barrier successfully contained and redirected the 2270P vehicle. The 

vehicle did not penetrate, under ride, or override the installation. Maximum dynamic and static 

deflections of the barrier during the test were 5.6 inches and 5.5 inches, respectively. No 

detached elements, fragments, or other debris were present to penetrate or show potential to 

penetrate the occupant compartment, or to present undue hazard to others in the area. Maximum 

occupant compartment deformation was 5.5 inches. The 2270P vehicle remained upright during 

and after the collision event. Maximum roll was 44 degrees. Occupant risk factors were within 

the limits specified in MASH. The vehicle remained within the exit box.

Therefore, the system described and detailed in the enclosed drawings 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 FHWA eligibility letters:

• This letter provides a AASHTO/ARTBA/AGC Task Force 13 designator that should be 

used for the purpose of the creation of a new and/or the update of existing Task Force 13 

drawing for posting on the on-line ‘Guide to Standardized Highway Barrier Hardware’ 

currently referenced in AASHTO Roadside Design Guide. 

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

and does not cover their structural features, nor conformity with the Manual on Uniform 

Traffic Control Devices.

• Any changes that may adversely influence the crashworthiness of the system 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 system 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 

Manual for Assessing Safety Hardware. 

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

B-225 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. 
5

• This letter shall not be construed as authorization or consent by the FHWA to use, 

manufacture, or sell any patented system for which the applicant is not the patent holder. 

The finding of eligibility is limited to the crashworthiness characteristics of the candidate 

system, 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

Office of Safety Technologies

Office of Safety 

Enclosures