July 11,2002 

 Refer to: HSA-10/CC78 

Barry D. Stephens, P.E. 

Senior Vice President, Engineering 

ENERGY ABSORPTION Systems, Inc. 

03617 Cincinnati Avenue 

Rocklin, CA 95765 

Dear Mr. Stephens: 

Your June 10 letter was delivered to Mr. Richard Powers of my staff on July 3 by 

Mr. Douglas Bernard. In that letter, you requested the Federal Highway 

Administration's (FHWA) acceptance of a re-designed truck mounted attenuator 

(TMA) called the Safe-Stop 180 TMA for use on Federal-aid projects as an 

National Cooperative Highway Research Program (NCHRP) Report 350 Test Level 3 

(TL-3) device. To support your request, you provided copies of a June 2002 

report by E-TECH Testing Services, Inc., entitled "NCHRP Report 350 Crash Test 

Results for the Safe-Stop 180 TMA." This report contained data on the NCHRP 

Report tests 3-50 and 3-51, which are the basic tests required for acceptance of 

a TMA. Optional TMA tests 3-52 and 3-53 were not run on this new version of the 

Safe-Stop. 

The Safe-Stop 180 is 4190-mm long, 2360-mm wide at the impact face, and weighs 

approximately 945 kilograms. Unlike the original Safe-Stop which had a tranport 

height of over 13 feet when in the raised position, the Safe-Stop 180 TMA 

consists of a bi-folding articulating frame assembly that contains a Safe-Stop 

Type A Cartridge immediately behind the impact face and a Safe-Stop Type B 

Cartridge near the support vehicle. The Type A and B cartridges are similar in 

internal design to the Type 1 and Type 2 cartridges used with the original SafeStop, but are wider. When the rearmost frame containing the Type A cartridge is 

pivoted 180 degrees vertically and folded on top of the front frame containing 

the Type B cartridge for tranport, the unit is only 6’-8” high. A schematic 

drawing of the Safe-Stop 180 is included with this letter as Enclosure 1. 

Enclosure 2 includes summary data on the two tests that were run. In both 

tests, the support vehicle weight was 8550 kg. This vehicle was blocked to 

prevent forward movement in the small car test, and rolled forward 6.9 m after 

impact by the pickup truck. The ridedown acceleration for the driver of the 

support vehicle in test 3-51 was not noted in the test report. 

Based on the information you provided and staff analysis of the data, we agree 

that the Safe-Stop 180 TMA, as designed and tested, meets the appropriate crash 

evaluation criteria suggested in NCHRP Report 350 for a TL-3 truck-mounted 

attenuator. It may be used on the National Highway System (NHS) when such use is 

requested by a State transportation agency. As with all TMAs, this acceptance is 

based on its reported crash test performance and is not intended to address 

other factors such as durability, the mobility of the support vehicle, roadinduced vibrations, maintainability, or the influence of moisture and 

temperature variations. Since it is a proprietary product, its use on the NHS 
is subject to the provisions of Title 23, Code of Federal Regulations, Section 

635.411 when such use is specified by the contracting agency. 

Sincerely yours, 

 (original signed by Harry W. Taylor) 

 for 

Carol H. Jacoby, P.E. 

Director, Office of Safety Design 

2 Enclosures 

 

Safe-Stop 180 TMA Crash Test Results - 10 of 43

Figure 1. Summary of Results - Safe-Stop 180 TMA Test 01-4307-001

t = 0.000 sec t = 0.144 sec t = 0.288 sec t = 0.432 sec t = 0.576 sec 

General Information

Test Agency ............................................................. E-TECH Testing Services, Inc.Test Designation .................................................... NCHRP 350 Test 3-50Test No. ................................................................... 01-4307-001Date .......................................................................... 5/30/02

Test Article

Type ......................................................................... Energy Absorption Systems, Inc.

.......................................................................... Safe-Stop 180 TMATM

Installation Length, (mm) ...................................... 4191 (overall system)Material and key elements ................................... (2) Aluminum Cartridges; LxHxW

.......................................................................... 1524 mm x 572 mm x 1219 mm

Foundation Type and Condition ................................... Asphalt, clean and dryTest Vehicle

Type ......................................................................... Production ModelDesignation .............................................................. 820C Small CarModel ....................................................................... 1993 Ford Festiva

Mass (kg)

Curb ................................................................. 837Test inertial ..................................................... 835Dummy............................................................. 75Gross Static ..................................................... 910

Impact Conditions

Speed (km/h) ........................................................... 99.0

Angle (deg).............................................................. 0Impact Severity (kJ) .............................................. 315.3

Exit conditions

Speed (km/h) ..........................................................Angle (deg) ............................................................

Occupant Risk Values

Impact Velocity (m/s)

x-direction .....................................................y-direction .....................................................

Ridedown Acceleration (g's)

x-direction .....................................................y-direction .....................................................

European Committee for Normalization (CEN) Val

THIV (km/h) .........................................................PHD (g's) ...............................................................ASI ........................................................................

Test Article Deflections (m)

Dynamic .................................................................Permanent .............................................................

Vehicle Damage

Exterior

VDS ................................................................CDC ...............................................................

Interior

OCDI ..............................................................

Post-Impact Vehicular Behavior (deg - rate gyro)

Maximum Roll Angle ...........................................Maximum Pitch Angle .........................................Maximum Yaw Angle ...........................................

Safe-Stop 180 TMA
Safe-Stop 180 TMA Crash Test Results - 16 of 43

Figure 6. Summary of Results - Safe-Stop 180 TMA Test 01-4307-002

t = 0.000 sec t = 0.240 sec t = 0.480 sec t = 0.720 sec t = 0.960 sec 

General Information

Test Agency ............................................................. E-TECH Testing Services, Inc.Test Designation .................................................... NCHRP 350 Test 3-51Test No. ................................................................... 01-4307-002Date .......................................................................... 4/2/02

Test Article

Type ......................................................................... Energy Absorption Systems, Inc.

.......................................................................... Safe-Stop 180 TMATM

Installation Length, (mm) ...................................... 4191 (overall system)Material and key elements ................................... (2) Aluminum Cartridges; LxHxW

.......................................................................... 1524 mm x 572 mm x 1219 mm

Foundation Type and Condition ................................... Asphalt, clean and dryTest Vehicle

Type ......................................................................... Production ModelDesignation ............................................................. 2000P Pickup

Model ....................................................................... 1992 GMC C-2500Mass (kg)

Curb ................................................................. 2084

Test inertial ..................................................... 2040Dummy ............................................................. N/AGross Static ..................................................... 2040

Impact Conditions

Speed (km/h) ........................................................... 99.0Angle (deg).............................................................. 0Impact Severity (kJ) .............................................. 771.2

Exit conditions

Speed (km/h) .........................................................Angle (deg) ...........................................................

Occupant Risk Values

Impact Velocity (m/s)

x-direction ....................................................y-direction ....................................................

Ridedown Acceleration (g's)

x-direction ....................................................y-direction ....................................................

European Committee for Normalization (CEN) Va

THIV (km/h) ........................................................PHD (g's) ..............................................................ASI .......................................................................

Test Article Deflections (m)

Dynamic ................................................................Permanent ............................................................

Vehicle Damage

Exterior

VDS ...............................................................CDC ..............................................................

Interior

OCDI .............................................................

Post-Impact Vehicular Behavior (deg - rate gyro)

Maximum Roll Angle ..........................................Maximum Pitch Angle ........................................Maximum Yaw Angle ..........................................

Safe-Stop 180 TMA