Memorandum

SENT VIA ELECTRONIC MAIL 

Subject: INFORMATION: FHWA Acceptance Letter B-181 Random Date: July 28, 2008 

Rubble Cavity Wall 

From: David A. Nicol, P.E. In Reply Refer To: HSSD/B-181 

Director, Office of Safety Design 

To: Ms. Victoria Brinkly 

 Highway Safety Engineer (HFL-17) 

 Western Federal Lands Highway Division 

This memorandum is in response to your request for FHWA’s acceptance of a roadside 

safety system for use on the NHS. 

 Name of system: Random Rubble Cavity Wall 

 Type of system: Aesthetic Stone Faced Concrete Barrier Guardwall 

 Test Level: NCHRP Report 350 TL-1 

 Testing conducted by: SwRI 

 Date of request: March 10, 2008 

 

You requested that we find this system acceptable for use on the NHS under the provisions of 

the NCHRP Report 350 “Recommended Procedures for the Safety Performance Evaluation 

of Highway Features.” 

Requirements 

Roadside safety systems should meet the guidelines contained in the NCHRP Report 350, 

"Recommended Procedures for the Safety Performance Evaluation of Highway Features". 

The FHWA Memorandum “ACTION: Identifying Acceptable Highway Safety Features” of 

July 25, 1997 provides further guidance on crash testing requirements of longitudinal 

barriers. 

Description

The Random Rubble Cavity Wall is 460 mm wide and composed of two different height 

sections. One section is 460 mm tall by 3.66 m long, and the other section is 610 mm tall by 

1.68 m long as shown in the attached drawings for reference. The sections are staggered 

such that there is a 610 mm tall section then a 460 mm tall section and then another 610 mm 
2

tall section. This alternating height pattern continues for the length of the installation. The 

guardwall consists of a reinforced concrete footing and a reinforced concrete core. 

Indigenous rock is placed on the sides and top of the concrete core. The majority of the rock 

is 300 mm to 460 mm in size with smaller rocks and masonry mortar used to complete the 

assembly of the guardwall. 

Crash Testing

Full-scale crash testing was conducted on this barrier. The TL-2 testing at 70 km/hr 

(43.5 mph) resulted in failure when the 2000P test vehicle drove over the barrier. Two TL-1 

tests were conducted at 50 km/hr (31 mph), NCHRP Report 350 Test 1-10 (RW-2) and Test 

1-11 (RW-1). Copies of the test data summary sheets for these tests are enclosed for 

reference. In both tests the vehicles were smoothly redirected and the occupant impact 

values were within the required limits. There was no deflection of the barrier in either test, 

nor was there any deformation of the occupant compartment. 

Findings 

Therefore, Random Rubble Cavity Wall described above and detailed in the enclosed 

drawings is acceptable for use on the NHS 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 letters of acceptance: 

• This acceptance 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 acceptance 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 our acceptance. 

• 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 

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

NCHRP Report 350. 

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

B-181 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 acceptance 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 acceptance letter 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. 

 3 Attachments 
3

 FHWA:HSSD:NArtimovich:tb:x61331:7/24/08 

S:/Directory Folder/NArtimovich/B181RubbleGuardwall WFLHD FIN (3).doc 

 cc: HSSD (Reader, HSA; Chron File, HSSD; DNicol, HSSD) 
-

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.. ROCKWALL

a.81m

REINFORCEDCONCRETE

FOOTING

Figure 1. VariableHeightGuardwallConstructionDetails

, ~~ ,- ~ ) : -"1
O.lO-see-_.

~ .--.

6.0m

N

00

4. GmonJ Infonnation

Test Agency

Test Nwnbct

Southwest Research Institule

RW-I

Test Dale 5iii'i94

5. Tes. Artide

Type

InslalJation Length (m)

Longillldinal

30.5

Banier Variable Height Stone MaSOnry OuanlwaJl

6. Soli Type and Condition

7. Test Vehicle

SlaJIdanl Soli, DIy Compacted

Type

D;;i'gnadon

Production Model

2000 P

Model 1989 Fcrd ruo

Mass (kg) Cum

Mass .(kg) Test Inertial

2,050

T,%.i

-- ~, Impact\

r"

~

_c.'

~

.1.

. i "

30.5m

8.5m

7:-'resfVCIiidc (Continued)

Mass (kg) DummY(I)

0 Estimated

Mass (kg) Gross S..tic

8. Impact Conditions

Speed (kmlb)

Angle (deg)

0.0

0.0

9. Exit Conditions

Speed (kmIh)

Angle (deg)

10. Occupant RIsk Values

II LFQI

i'i'iiF'BFB'

InpacfVelocltY (mls) LFQlI2000

x-dUection

y-direction

Rldedown Acceleration (g's)

15 EStimalid

5 Estim.1cd

x-diiCdion

Figure 8. Summary of Test Conditions and Results -Test RW-l

ro.-lUdcdownAcXderation(:'s)

15 y-dirtttion

2,039 11. Test ArticleDeflection(no)

Dyaamic

40.2 Permancot

25 12. Vehld. Damage

Exterior

0 CDC

Inlclior

'QCj)(

0.58 13. P...I-Impad Vchicul8r Beba'l'ior

1.I5 Maximum ReD Angle (<leg)

MaxImum Pilch Angle (deg)

0.02 I Maximum Yaw Angle (dog)
10.7m

,~

200

+>- 0\ )-

4. Gemrnl [,,(ormalion

Test Agency

Test Number

Soalhwest Resean:h Institute

RW.2

Test Date 5/lJi94

5. Test Ai1ide

Type

Installation Length (m)

Longitudinal

30T

Banie< Variable Height Stone Mawnry Guardwall

6. Soil Type ami C<JnditiOD Standard SoU. DIy Compacted

7. Test Vebide

Type Production Model

Designation 820C

Model i9s9 fud Fe<tiva

M"" (kg)Cwb 845

1.1... (kg) Test lmertial ii40

:sm 205m -~-j l =L::L-LI~ r-y,,, >0 "" >=:=.21::-.:1[=

[~ :-3 7. Test Vehicle (Continued) HI. RidCdo'm A<:<:deration(g'.)

Mass (kg) Dummy(,) y-illrection

M:!Ss (kg) Gross Static

15

915 11. Test Article OeJIection (m)

Dynamie 0.0

0.0

8. Impact Conditions

Speed (kmJh) 40.2

10

Penn anent

A'1g!e (deg)

~cnditiollS

12. Vchicle Damage

Extcrior

Speed (kmib)

~

0

'0

VDS

COC

IILf-QI

iiFFENi

1~ O«u~tRilkVroues

Impact Velocity (mf.)

Interior

OCD! 112000

x-direetion 13. Post.lmpact V<hicuIar Behavior

Maximum Roll Aag!e (~)

1.15

y-diredion Q]3

Ridedowo Acceleration (g'.)

15 Estimated

Maximum PilCh Aagle (dog) 5 Estimated

~-<Ii=IiOD 0.31 Maximwa Yaw Aagle (deg) 0 Bstimated

Figure 14. Summary of Test Conditions and Results -Test RW-2