July 10, 2003 Refer to: HSA-10/CC-78A Barry D. Stephens, P.E. Senior Vice President of Engineering ENERGY ABSORPTION Systems, Inc. 3617 Cincinnati Avenue Rocklin, California 95765 Dear Mr. Stephens: Your April 8 and April 23 letters were recently delivered to Mr. Richard Powers of my staff by Mr. Douglas Bernard. In those letters, you requested the Federal Highway Administration's (FHWA) acknowledgement that your modified Safe Stop 180 truck mounted attenuator (TMA) successfully met the evaluation criteria for the supplemental TMA tests recommended in the National Cooperative Highway Research Program (NCHRP) Report 350. To support your request, you provided copies of an April 2003 report by E-TECH Testing Services, Inc., entitled "NCHRP Report 350 Crash Test Results for the Improved Safe-Stop 180 TMA which contained data on both of the required TMA tests (i.e., test 3-50 and a modified test 3-51 as described below), and on the optional tests (tests 3-52 and 3-53). With the April 23 letter, you submitted a supplemental report that contained the results of the standard TMA test 3-51. However, you requested that the FHWA withhold issuance of its formal acceptance letter until July when the new Safe-Stop 180 was expected to be ready for distribution. Like the original Safe-Stop 180, the improved version is 4190-mm long and 2360-mm wide at the impact face, but weighs approximately 5 kilograms less (940 kg). Although there were some minor external changes made, the most significant change was in the internal arrangement of the individual energy-absorbing cells to accommodate off-center and/or angle impacts into the end of the unit. Enclosure 1 is a drawing of the improved Safe Stop 180. Enclosure 2 consists of the summary sheets for Report 350 tests 3-50, 3-51, 3-52, and 3-53. All evaluation criteria were met, but in each test the actual impact speeds were below the nominal speed of 100 km/h. In fact, for modified test 3-51 (see Enclosure 3) where the support vehicle was physically blocked to minimize forward movement and in test 3-52, the reported impact speeds were slightly below the speed tolerance recommended for these tests. Since the impact speed was within tolerance for the standard test 3-51 and ridedown acceleration reported in test 3-52 was 17.8 g s (2.2 g s below the allowable limit), I will accept the results of these two tests
in spite of the reported low Impact Severity (IS). Please note section 3.3.5 in Report 350 recommends that the actual IS be equal to or greater than the target value for a TMA. In none of the tests you conducted was the target value obtained. However, in the two tests noted above none of the evaluation criteria were at the upper limit. I am reasonably confident that the improved Safe Stop 180 would meet all evaluation criteria if the target IS had been met, but at some point in the future the FHWA may not accept the results of new tests for TMAs (or crash cushions) in which the target impact severities are not substantially met and one or more of the evaluation criteria are at or near the upper limits. In light of the above discussion, your improved Safe Stop 180 is acceptable for use on the National Highway System as a TL-3 TMA when such use is acceptable to the contracting authority. Since the improved version is similar in outward appearance to the original design, the new unit should be clearly marked in some manner so the two designs can be readily differentiated in the field. As noted above, your modified test 3-51 consisted of a blocked support vehicle and all evaluation criteria were met except the ridedown acceleration, which was reported to be 20.7 g s. Since the support vehicle could not roll forward when blocked, a truck of any weight over 9,000 kg could be used as a support vehicle and similar accelerations would be likely. I agree that a heavier support vehicle can be used with the improved Safe Stop 180 at the discretion of the contracting authority and with its understanding that ridedown accelerations will approach and may surpass the 20 g limit under some impact conditions when the support vehicle is significantly heavier than 9,000 kg. Sincerely yours, 2 3 Enclosures (original signed by Michael S. Griffith) Michael S. Griffith Acting Director, Office of Safety Design Office of Safety
E-TECH Testing Services, Inc. 3617 B Cincinnatti Avenue Rocklin, CA 95765 PHONE (916) 645-8188 FAX (916) 645-3653 A Quixote Company t = 0.000 sec t = 0.048 sec t = 0.096 sec t = 0.144 sec t = 0.192 sec t = final Test Article: Safet-Stop 180 TMA NCHRP 350 Occupant Risk Values Impact Velocity (m/s) x-direction... 11.1 y-direction... -0.2 Ridedown Acceleration (g's) x-direction... -16.2 y-direction... 8.1 Support Vehicle Acceleration (g's) x-direction... N/A European Committee for Normalization (CEN) Values THIV (km/h)... 39.9 PHD (g's)... 16.7 ASI... 2.1 Test Article Deflections (m) Dynamic... 2.2 Permanent... 2.2 Vehicle Damage Exterior VDS... FD-6 CDC... 12FDEW5 Interior OCDI... AS0000000 Deformation (mm - max)... 100 Post-Impact Vehicular Behavior (deg - rate gyro) Maximum Roll Angle... 5.6 Maximum Pitch Angle... -25.7 Maximum Yaw Angle... -8.2 General Information Test Agency... E-TECH Testing Services, Inc. Test Designation... NCHRP 350 Test 3-50 Test No.... 01-4307-006 Date... 3/18/03 Test Article Type... Energy Absorption Systems, Inc.... Safe-Stop 180 TMA TM 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... Concrete, clean and dry Test Vehicle Type... Production Model Designation... 820C Model... 1988 Ford Festiva Mass (kg) Curb... 809 Test inertial... 828 Dummy... 75 Gross Static... 903 Support Vehicle Model... 1970 GMC 7500 T/A Dump Test Inertial Mass (kg)... 8550 Restraint... Against rigid barrier Impact Conditions Speed (km/h)... 97.7 Angle (deg)... 0 Impact Severity (kj)... 304.7 Safe-Stop 180 TMA Crash Test Results - 12 of 72 Figure 1. Summary of Results - Safe-Stop 180 TMA Test 01-4307-006
t = 0.000 sec t = 0.048 sec t = 0.096 sec t = 0.144 sec t = 0.192 sec t = final E-TECH Testing Services, Inc. Safe-Stop 180 TMA Crash Test Results - 10 of 34 General Information Test Agency... E-TECH Testing Services, Inc. Test Designation... NCHRP 350 Test 3-51 Test No.... 01-4307-007 Date... 4/16/03 Test Article Type... Energy Absorption Systems, Inc.... Safe-Stop 180 TMA TM 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... Concrete, clean and dry Test Vehicle Type... Production Model Designation... 2000P Pickup Model... 1990 Chevrolet C2500 Mass (kg) Curb... 1980 Test inertial... 1998 Dummy... N/A Gross Static... 1998 Support Vehicle Model... 1970 GMC 7500 T/A Dump Test Inertial Mass (kg)... 8550 Restraint... Park brakes on / second gear Impact Conditions Speed (km/h)... 96.4 Angle (deg)... 0 Impact Severity (kj)... 715.8 NCHRP 350 Occupant Risk Values Impact Velocity (m/s) x-direction... 9.0 y-direction... -0.3 Ridedown Acceleration (g's) x-direction... -17.2 y-direction... -2.7 Support Vehicle Acceleration (g's) x-direction... 5.9 European Committee for Normalization (CEN) Values THIV (km/h)... 32.4 PHD (g's)... 17.2 ASI... 1.3 Test Article Deflections (m) Dynamic... 3.3 Permanent... 3.2 Vehicle Damage Exterior VDS... FD-6 CDC... 12FDEW5 Interior OCDI... AS0000000 Deformation (mm - max)... Negligible Post-Impact Vehicular Behavior (deg - rate gyro) Maximum Roll Angle... -3.8 Maximum Pitch Angle... -3.9 Maximum Yaw Angle... -5.3 Figure 1. Summary of Results - Safe-Stop 180 TMA Test 01-4307-007 Test Article: Safet-Stop 180 TMA
E-TECH Testing Services, Inc. 3617 B Cincinnatti Avenue Rocklin, CA 95765 PHONE (916) 645-8188 FAX (916) 645-3653 A Quixote Company t = 0.000 sec t = 0.048 sec t = 0.096 sec t = 0.144 sec t = 0.192 sec t = final Test Article: Safet-Stop 180 TMA NCHRP 350 Occupant Risk Values Impact Velocity (m/s) x-direction... 8.8 y-direction... 0.5 Ridedown Acceleration (g's) x-direction... -17.9 y-direction... 6.0 Support Vehicle Acceleration (g's) x-direction... 5.2 European Committee for Normalization (CEN) Values THIV (km/h)... 32.0 PHD (g's)... 18.2 ASI... 1.3 Test Article Deflections (m) Dynamic... 3.5 Permanent... 3.5 Vehicle Damage Exterior VDS... FD-6 CDC... 12FDEW5 Interior OCDI... AS0000000 Deformation (mm - max)... Negligible Post-Impact Vehicular Behavior (deg - rate gyro) Maximum Roll Angle... -12.9 Maximum Pitch Angle... -8.1 Maximum Yaw Angle... --117.0 General Information Test Agency... E-TECH Testing Services, Inc. Test Designation... NCHRP 350 Test 3-52 Test No.... 01-4307-003 Date... 2/25/03 Test Article Type... Energy Absorption Systems, Inc.... Safe-Stop 180 TMA TM 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... Concrete, clean and dry Test Vehicle Type... Production Model Designation... 2000P Pickup Model... 1990 Chevrolet C2500 Mass (kg) Curb... 2006 Test inertial... 1988 Dummy... N/A Gross Static... 1988 Support Vehicle Model... 1970 GMC 7500 T/A Dump Test Inertial Mass (kg)... 8550 Restraint... Park brakes on / second gear Impact Conditions Speed (km/h)... 95.7 Angle (deg)... 0 Impact Severity (kj)... 702.4 Safe-Stop 180 TMA Crash Test Results - 24 of 72 Figure 11. Summary of Results - Safe-Stop 180 TMA Test 01-4307-003
E-TECH Testing Services, Inc. 3617 B Cincinnatti Avenue Rocklin, CA 95765 PHONE (916) 645-8188 FAX (916) 645-3653 A Quixote Company t = 0.000 sec t = 0.120 sec t = 0.240 sec t = 0.360 sec t = 0.480 sec t = final General Information Test Agency... E-TECH Testing Services, Inc. Test Designation... NCHRP 350 Test 3-53 Test No.... 01-4307-004 Date... 2/27/03 Test Article Type... Energy Absorption Systems, Inc.... Safe-Stop 180 TMA TM 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... Concrete, clean and dry Test Vehicle Type... Production Model Designation... 2000P Pickup Model... 1989 Chevrolet C2500 Mass (kg) Curb... 2038 Test inertial... 2021 Dummy... N/A Gross Static... 2021 Support Vehicle Model... 1970 GMC 7500 T/A Dump Test Inertial Mass (kg)... 8550 Restraint... Park brakes on / second gear Impact Conditions Speed (km/h)... 97.0 Angle (deg)... 10 Impact Severity (kj)... 733.7 NCHRP 350 Occupant Risk Values Impact Velocity (m/s) x-direction... 8.3 y-direction... 0.9 Ridedown Acceleration (g's) x-direction... -17.3 y-direction... 7.6 Support Vehicle Acceleration (g's) x-direction... 5.5 European Committee for Normalization (CEN) Values THIV (km/h)... 30.1 PHD (g's)... 18.1 ASI... 1.1 Test Article Deflections (m) Dynamic... 3.1 Permanent... 3.1 Vehicle Damage Exterior VDS... FD-6 CDC... 12FDEW5 Interior OCDI... AS0000000 Deformation (mm - max)... Negligible Post-Impact Vehicular Behavior (deg - rate gyro) Maximum Roll Angle... -16.2 Maximum Pitch Angle... -5.8 Maximum Yaw Angle... -110.7 Figure 16. Summary of Results - Safe-Stop 180 TMA Test 01-4307-004 Test Article: Safet-Stop 180 TMA Safe-Stop 180 TMA Crash Test Results - 30 of 72
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 Safe- Stop, 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, 2 Enclosures (original signed by Harry W. Taylor) for Carol H. Jacoby, P.E. Director, Office of Safety Design
t = 0.000 sec t = 0.144 sec t = 0.288 sec t = 0.432 sec t = 0.576 sec t = final E-TECH Testing Services, Inc. Safe-Stop 180 TMA Crash Test Results - 10 of 43 General Information Test Agency... E-TECH Testing Services, Inc. Test Designation... NCHRP 350 Test 3-50 Test No.... 01-4307-001 Date... 5/30/02 Test Article Type... Energy Absorption Systems, Inc.... Safe-Stop 180 TMA TM 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 dry Test Vehicle Type... Production Model Designation... 820C Small Car Model... 1993 Ford Festiva Mass (kg) Curb... 837 Test inertial... 835 Dummy... 75 Gross Static... 910 Impact Conditions Speed (km/h)... 99.0 Angle (deg)... 0 Impact Severity (kj)... 315.3 Figure 1. Summary of Results - Safe-Stop 180 TMA Test 01-4307-001 Safe-Stop 180 TMA Exit conditions Speed (km/h)... N/A Angle (deg)... N/A Occupant Risk Values Impact Velocity (m/s) x-direction... 11.2 y-direction... 0.4 Ridedown Acceleration (g's) x-direction... -17.1 y-direction... -4.2 European Committee for Normalization (CEN) Values THIV (km/h)... 40.3 PHD (g's)... 17.1 ASI... 1.9 Test Article Deflections (m) Dynamic... 2.5 Permanent... 2.3 Vehicle Damage Exterior VDS... FD-6 CDC... 12FDEW5 Interior OCDI... AS0000000 Post-Impact Vehicular Behavior (deg - rate gyro) Maximum Roll Angle... 2.2 Maximum Pitch Angle... -18.1 Maximum Yaw Angle... -7.8
t = 0.000 sec t = 0.240 sec t = 0.480 sec t = 0.720 sec t = 0.960 sec t = 1.20 sec E-TECH Testing Services, Inc. Safe-Stop 180 TMA Crash Test Results - 16 of 43 General Information Test Agency... E-TECH Testing Services, Inc. Test Designation... NCHRP 350 Test 3-51 Test No.... 01-4307-002 Date... 4/2/02 Test Article Type... Energy Absorption Systems, Inc.... Safe-Stop 180 TMA TM 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 dry Test Vehicle Type... Production Model Designation... 2000P Pickup Model... 1992 GMC C-2500 Mass (kg) Curb... 2084 Test inertial... 2040 Dummy... N/A Gross Static... 2040 Impact Conditions Speed (km/h)... 99.0 Angle (deg)... 0 Impact Severity (kj)... 771.2 Safe-Stop 180 TMA Exit conditions Speed (km/h)... N/A Angle (deg)... N/A Occupant Risk Values Impact Velocity (m/s) x-direction... 8.7 y-direction... 0.2 Ridedown Acceleration (g's) x-direction... -19.8 y-direction... -5.1 European Committee for Normalization (CEN) Values THIV (km/h)... 31.4 PHD (g's)... 19.8 ASI... 1.3 Test Article Deflections (m) Dynamic... 3.5 Permanent... 3.2 Vehicle Damage Exterior VDS... FD-6 CDC... 12FDEW5 Interior OCDI... AS0000000 Post-Impact Vehicular Behavior (deg - rate gyro) Maximum Roll Angle... -2.0 Maximum Pitch Angle... -5.2 Maximum Yaw Angle... 2.7 Figure 6. Summary of Results - Safe-Stop 180 TMA Test 01-4307-002