Federal Highway Administration
400 Seventh St., S.W.
Washington, D.C. 20590
May 8, 2007
In Reply Refer To: HSSD/B-160
Mr. Owen S. Denman, PE
President and CEO
Barrier Systems Inc.
180 River Road
Rio Vista, CA 94571-1208
Dear Mr. Denman:
Thank you for your letter of December 18, 2006, requesting the Federal Highway Administration (FHWA) acceptance of your company's BarrierGuardTM 800 (BG 800) – Variable Length Barrier (BGVLB) for use on the National Highway System (NHS) under the provisions of the National Cooperative Highway Research Program (NCHRP) Report 350 "Recommended Procedures for the Safety Performance Evaluation of Highway Features". Accompanying your letter were crash test reports on testing of your company's BarrierGuardTM 800 system in regular and minimum deflection applications and test reports on the Reactive Tension System (RTS) and Quickchange Moveable Barrier (QMB) systems of April 2000, including results of the NCHRP 350 test 3-11 conducted to evaluate the performance of a concrete RTS Variable Length Barrier section under direct impact conditions.
Longitudinal barrier systems should meet the guidelines contained in the NCHRP Report 350, "Recommended Procedures for the Safety Performance Evaluation of Highway Features". FHWA Memorandum “Action: Identifying Acceptable Highway Safety Features” of July 25, 1997 provides further guidance on crash testing of longitudinal barriers.
The previously approved BarrierGuardTM 800 systems (FHWA acceptance letters B-131 and B-158) are high containment and low deflection steel barriers designed for both permanent applications and temporary use in roadwork situations, preventing penetration of errant vehicles into working areas. The modifications of the system (the use of intermediate anchoring along with T-tops) allow lowering the deflection from maximum 1000 mm in regular BarrierGuardTM 800 system to approximately 300 mm in BarrierGuardTM 800 Minimum Deflection applications. BarrierGuardTM 800 Variable Length Barrier is designed to provide clearance and flexibility for expansion joints on bridges, overpasses, and roadways. The BGVLB is designed to be used with regular and minimum deflection applications of BarrierGuardTM 800 system when it is anchored to a bridge deck (or other highway feature) on both sides of a structural expansion joint. The BGVLB allows slow relative movement for conditions such as thermal expansion/contraction, bridge joint movement, etc., but hydraulically locks when the movement is fast, such as during a vehicle impact with the barrier. Each BGVLB provides 355 mm (14") of travel. The units are deployed with a nominal length of 1.6 m (63") and are capable of extending or retracting 178 mm (7"). Multiple BGVLB units can be attached to each other in order to obtain greater movement across a highway expansion joint. The BGVLB is always used with the T-Top used to aid in the redirection and stability of the vehicle after impact. If used with BarrierGuardTM 800 Minimum Deflection system, BGVLB can be located between either 6-meter or 12-meter sections but there should be no foundation anchors within 6 meters of either end of the BGVLB attachment. If used with regular BarrierGuardTM 800, the T-top attachment should be used for 12 meters on either side of the BGVLB and terminate with a transition section.
Drawings of the BarrierGuardTM 800 – Variable Length Barrier and of the T-top transition are provided in Enclosure 1.
The NCHRP Report 350 requires that in order for the length-of-need of longitudinal barriers to meet the NCHRP Report 350 test level 3 criteria they must successfully pass tests 3-10 and 3-11 while test S3-10 is optional. However, since your company’s RTS VLB was successfully tested in April 2000, including testing of CRTS VLB under direct impact conditions (FHWA acceptance letter HSA/B-69), you requested to waive a full crash testing of the BGVLB. The assumption was that BGVLB uses the same telescoping mechanisms and will perform similarly to RTS VLB.
We noted the RTS VLB was tested in a concrete moveable barrier system which is more massive than the steel systems in your present request. However, we eventually concluded that the difference in lateral stiffness between the systems in which the VLB will be used would not significantly affect the performance and, most importantly, it is unlikely that its lap will cause snagging of the impacting vehicles under direct impact conditions.
Therefore, I concur that BarrierGuardTM 800 – Variable Length Barrier, as described above, meets the appropriate evaluation criteria for the NCHRP 350 test level 3 longitudinal barriers and may be used at all appropriate locations on the 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. Since no testing was conducted on the BGVLB, I encourage you to monitor its in-service performance and report to me any issues found.
The BGVLB is accepted to be used with different applications of BarrierGuardTM 800, including regular BarrierGuardTM 800, BarrierGuardTM 800 - Minimum Deflection and BarrierGuardTM 800 Gate applications. This acceptance is based on the reported crash performance of the BarrierGuardTM 800 – Variable Length Barrier system and is not intended to address the
long-term durability of the unit. Further, I am assuming that production models will be identical to the prototype test units.
Please note the following standard provisions that apply to the FHWA letters of acceptance:
George E. Rice, Jr.
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