Federal Highway Administration
400 Seventh St., S.W.
August 15, 2007
In Reply Refer To: HSSD/CC-57B
Mr. Barry D. Stephens
Sr. Vice President Engineering
Energy Absorption Systems, Inc.
3617 Cincinnati Avenue
Rocklin, CA 95765
Dear Mr. Stephens:
In your letter of May 04, 2007, you requested formal FHWA acceptance of a new version of your redirective, non-gating crash cushion called the QuadGuard® Elite system, reduced to a length of 8 bays. To support your request, you provided copies of a E-TECH Testing Services Inc. report dated December 2006, entitled “NCHRP Report 350 TL-3 Crash Test Results for the 8 Bay QuadGuard® Elite”, test videos and drawings of the system.
Crash cushions 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 support structures.
The Energy Absorption Systems, Inc. QuadGuard® Elite System is a crash cushion intended to shield highway hazards subjected to the possibility of high impact frequency. The system is available in a variety of lengths (number of bays) and widths (backup configurations). The original 11 bay test level 3 (TL-3) QuadGuard® Elite was accepted on December 30, 1998, (FHWA acceptance letter CC-57). The new 8 bay QuadGuard® Elite is essentially the same system with the elimination of the last three bays of the 11 bay version.
The original test data demonstrated that the 11 bay QuadGuard® Elite system has an excess capacity. Further, 8 years of field experience confirmed that the cylinders performed as intended after multiple impacts. Therefore, you decided to develop an 8 bay alternative which would maintain essentially the same performance characteristics while being less costly and suitable for a greater number of sites.
Design details for the 8 bay QuadGuard® Elite system are shown in Enclosure 1. Major assemblies include the Cylinder, Diaphragm, Fender Panel, Monorail, Nose, and Backup. It has a nominal length of 8.10 m (26.6 ft) and can be configured with backup widths of 610 mm, 762 mm, 914 mm, 1753 mm, and 2286 mm (24”, 30”, 36”, 69” and 90”). The QuadGuard® Elite System consists of reusable high density polyethylene plastic (HDPE) energy absorbing cylinders surrounded by a frame of steel Quad-Beam® guardrail that can telescope rearward during head-on impacts. There are no cylinders in the first two bays. The QuadGuard® Elite System has a center monorail that resists lateral movement during side angle impacts and a backup structure that resists movement during head-on impacts. The nose assembly consists of a flexible nose wrap and an energy absorbing HDPE cylinder. Transitions from the system to the hazard located behind the system are available and may be required depending on site conditions.
Two thicknesses of HDPE cylinders are used in the 8 bay Elite System. Bays 3 through 5 contain 51 mm (2”) thick cylinders measuring 813 mm (32”) in diameter and 508 mm (20”) wide. Bays 6 through 8 contain 102 mm (4”) thick cylinders also measuring 813 mm (32”) in diameter and 508 mm (20”) wide. The 102 mm (4”) thick cylinders are actually a composite of two 51 mm (2”) thick cylinders nested together. The 711 mm (28”) diameter innermost cylinder is also used in the nose of the system. All cylinders are secured within the system by means of 13 mm (0.51”) diameter galvanized wire rope tethers which pass through adjacent cylinders and wrap around the support leg of the diaphragm between them. In this way two tethers hold each cylinder in place between diaphragms. The portion of the tether that passes through the cylinders is jacketed by a steel tube to prevent the wire rope from tearing into the HDPE cylinder. The ends of each tether are tied together with standard wire rope clamps.
Test article installation
The test article was rigidly secured to a 27.6 MPa unreinforced concrete foundation using MP-3TM anchors. The test article was anchored with standard MP-3 anchor bolts which are 19 mm (0.75”) diameter by 178 mm (7”) long ASTM A-193 Grade B7 polyester grouted studs embedded to a depth of 140 mm (5.5”).
The NCHRP Report 350 requires that in order for redirective, non-gating crash cushions to meet the NCHRP 350 TL-3 criteria they must successfully pass tests 3-30, 3-31, 3-32, 3-33, 3-36, 3-37, 3-38 while test 3-39 is intended to test crash cushions in hits by opposing traffic in median and roadside installations. Since the 11 bay QuadGuard® Elite in different width configurations was previously accepted as a TL-3 device, and because the 8 bay QuadGuard® Elite system is essentially the same as the first 8 bays of the 11 bay QuadGuard® Elite, and the small car 820C vehicle did not collapse beyond bay 8 in the testing of the 11 bay system, we agree with your assumption that running test 3-31 with 2000P vehicle would be sufficient to evaluate the performance of the 8 bay QuadGuard® Elite system.
According to the information you provided the test article performed successfully in test 3-31. Occupant risk factors were within the limits specified in NCHRP 350. The test article damage was categorized as "superficial" since all major components were reusable without straightening.
There was no damage to the concrete anchoring system and no significant debris expelled during the impact. The system restored to its initial position. Summary of tests results are presented in Enclosure 2.
We therefore agree that 8 bay QuadGuard® Elite system as described above meets the appropriate evaluation criteria for NCHRP 350 TL-3 devices and may be used at all appropriate locations on the National Highway System (NHS) when selected by the contracting authority, subject to the provisions of Title 23, Code of Federal Regulations, Section 635.411, as they pertain to proprietary products. Also, please note that this acceptance is based on the reported crash performance of the device and is not meant to address its installation, maintenance or repair characteristics.
Please note the following standard provisions that apply to the FHWA letters of acceptance:
George E. Rice, Jr.
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