U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
US Department of Transportation
Subject: ACTION: National Cooperative Highway Research Program (NCHRP) Report 350 Hardware Compliance Dates
Date: August 28, 1998
From: Director, Office Engineering
Reply to Attn of: HNG-14
|To:||Directors of Field Services
Federal Lands Highway Program Administrator
On August 28, the Federal Highway Administration's (FHWA) Executive Director, Anthony R. Kane concurred in the proposed AASHTO-FHWA Agreement on the NCHRP Report 350 Implementation that was prepared by the AASHTO 350 Task Force and submitted to him on July 1. In this document the task force recommends that the October 1, 1998, deadline for the use of NCHRP Report 350-tested roadside hardware on the National Highway System (NHS) be extended for selected hardware categories. A summary table showing extended implementation dates for several categories of roadside appurtenances, including some work zone hardware, is attached. The information in this memorandum, as it relates to implementation dates for complying with NCHRP 350 testing and evaluation criteria, supercedes such information in the July 25, 1997, memorandum on "Identifying Acceptable Highway Safety Features." Division offices should work with their States to update the State standard drawings, specifications and policies to ensure crash worthy barriers will be incorporated into NHS projects in accordance with the attached implementation schedule.
Although the table and the accompanying footnotes are generally self-explanatory, there are several items that warrant special attention. The implementation date for the NCHRP Report 350-tested guardrail to bridge rail transitions has been extended to October 1, 2002. However, all new transitions must continue to satisfy NCHRP Report 230 evaluation criteria. Design details for several NCHRP Report 230 transitions have previously been distributed via FHWA Technical Advisories T 5040.26, dated January 28, 1998, and T 5040.34, dated June 8, 1993.
Although in most cases, the AASHTO-FHWA agreement states that upgrading of existing hardware that meets NCHRP Report 230 requirements is not required on 3R projects, an exception is made for w-beam guardrail terminals and cable guardrail terminals. Specifically, it should be noted that although the agreement provides considerable flexibility in retaining existing hardware meeting NCHRP Report 230 criteria on 3R projects, such flexibility does not exist for w-beam guardrail terminals. Also, please note that an extension or exception may be made in the future for the 3-strand cable anchor if planned NCHRP Report 350 tests of the current design are unsuccessful.
Also, a change from the guidance in the FHWA memorandum "Traffic Barrier Safety Policy and Guidance" dated September 29, 1994, is that existing Breakaway Cable Terminals (BCT's) should now be replaced with end treatments meeting NCHRP 350 criteria in conjunction with 3R work. A recent NCHRP Report 350 head-on test of the BCT with an 820-kg car at the test level 2 (TL-2) impact speed of 70 km/h resulted in unacceptable passenger compartment intrusion indicating clearly that the BCT is too stiff to accommodate end-on hits, even at reduced speeds.
Regarding work zone devices, the implementation date for Category II devices (portable sign stands with signs, Type I, II and III barricades, vertical panels, intrusion alarms and other devices not expected to cause significant velocity change) has been extended to October 1, 2000. Under Category III, the implementation date for truck mounted attenuators and work zone crash cushions remains at October 1, 1998, but is extended until October 1, 2002, for other devices within the category. Other such devices include portable concrete barriers and devices similar to Category II but with masses that could cause significant velocity change. Portable concrete barriers with joints that fail to transfer tension and moment from one segment to another must be phased out by October 1, 2000, unless an engineering study or in-service performance study demonstrates the barrier will provide the performance requirements of the site where it is to be used. Also note that other Category III devices (other than portable concrete barriers, work zone crash cushions and truck mounted attenuators), such as portable signs with hard (plywood, aluminum) substrate, that have not been demonstrated to be crash worthy must be phased out on a system wide basis by October 1, 2002. Details on acceptable work zone hardware are contained in my August 28 memorandum, "Crash Tested Work Zone Traffic Devices."
Implementation dates for Work Zone Category IV devices (arrow panels, variable message boards, and portable traffic signals/lighting equipment) and for Miscellaneous Hardware (see Footnote 18) have been extended indefinitely pending the results of additional research and analysis. Appropriate dates are expected to be announced within 2 years.
Henry H. Rentz