Figure 1. Short Radius Guardrail Drawing (C-2f) from WsDOT.

   
BACKGROUND
    One of the earliest known series of tests of a short radius guardrail system was conducted by Southwest Research Institute (SwRI) per the NCHRP Report 230 guidelines in 1988 (ref. 1). Later, SwRI conducted a series of tests for the Yuma County (AZ) public works department and many of the tests were considered successful per the NCHRP Report 230 criteria. Another series of tests were conducted by Texas Transportation Institute (TTI) per the NCHRP Report 230 and NCHRP Report 350 guidelines under two different research projects in the early 1990s (ref. 4 and 6). More, recently, Midwest Roadside Safety Facility (MwRSF) embarked on testing a T-Intersection curved rail design per the NCHRP Report 350 guidelines, but efforts to date have not been successful (ref. 7 and 8).

OBJECTIVE
    The long term objective of this study is to design and test an NCHRP Report 350 TL-3 compliant short radius guardrail system. The short term objective of this study (Phase I) is to investigate the performance of previously tested short radius systems to determine if some of the previously tested short radius guardrail systems meet NCHRP Report 350 TL- 2 criteria. If basic engineering review does not yield a TL-2 equivalency of a previously tested system, then computer simulation will be conducted to evaluate such a system under a TL-2 conditions. Full scale crash test will be conducted if needed to obtain FHWA approval for such a system.
    The objective of Phase II of this research is to identify design parameters critical to develop and crash test a short radius system that meets NCHRP Report 350 TL-3 criteria.

BENEFITS
    To date, a short radius guardrail for T– Intersections has not been successfully crash tested per NCHRP Report 350 TL- 3 criteria. This type of field condition exists in numerous locations and a design is needed that performs acceptably under NCHRP Report 350 conditions. Ideally, a TL-3 design would serve the greatest number of locations, but a successful TL-2 design would greatly enhance motorist safety in a large number of locations.

WORK PLAN
    To better address the objective of this endeavor, the project is to be split into two phases. Phase I will include the literature and engineering review, and computer simulation of a T-intersection guardrail system under NCHRP Report 350 TL-2 conditions, and a possibility for a TL-2 crash test for the provided system.
    Phase II of the project will consist of engineering design, numerical simulation, and subsequently full scale crash testing of a promising system using NCHRP Report 350 TL-3 test conditions and evaluation criteria. This proposal addresses Phase I effort. Phase II has been funded at this time.
    Detailed Work Plan

 
Draft Final Report:   EVALUATION OF EXISTING T-INTERSECTION GUARDRAIL SYSTEMS
FOR EQUIVALENCY WITH NCHRP REPORT 350 TL-2 TEST CONDITIONS - July 2010

TTI Research Supervisor: Akram Abu-Odeh, Ph.D. Texas Transportation Institute Texas A&M University System TAMU 3135 College Station, Texas 77843-3135 (979) 862-3379 A-Abu-Odeh@ttimail.tamu.eduv

Pooled Fund Technical Representative: Paul Fossier Louisiana Department of Transportation P.O. Box 94245 1201 Capitol Access Road Baton Rouge, LA 70804-9245 (225)379-1323 PaulFossier@dotd.louisiana.gov

QUARTERLY PROGRESS REPORTS:

March 2010 Progress Report
March 2008 Progress Report
December 2007 Progress Report
September 2007 Progress Report

____________________
(1.) Bronstad, M.E., L.R. Calcote, M. H. Ray, and J.B. Mayer, Guardrail-Bridge Rail Transition Designs, Volume I, Report No. FHWA/RD-86/178, Southwest Research Institute, San Antonio, Texas, April 1988.
(2.) Myer, J.B, Full-Scale Crash Testing of Approach Guardrail for Yuma County Public Works Department, Final Report, Project No.06-2111, Southwest Research Institute, San Antonio, Texas, 1989.
(3.) Curved W-Beam Guardrail Installations at Minor Roadway Intersections, Federal Highway Administration (FHWA), U.S. Department of Transportation, Technical Advisory T5040.32, April 13, 1992.
(4.) Ross, H.E. Jr., Bligh, R.P., Parnell, C.B., Bridge Railing End Treatments at Intersecting Streets and Drives, Report No. FHWA TX-91/92-1263-1F, Texas Transportation Institute, College Station, Texas, August 1992.
(5.) Ross, H. E. Jr., D. L. Sicking, R. A. Zimmer, and J. D. Michie, Recommended Procedures for the Evaluation of Highway Features, NCHRP 350, Transportation Research Board, Washington, D. C., 1993.
(6.) Bligh, Roger P., Hayes E. Ross, Jr., and Dean C. Alberson, Short-Radius Thrie Beam Treatment for Intersecting Streets and Drives, Report No. FHWA/TX-95/1442-1F, Texas Transportation Institute, College Station, Texas, November 1994.
(7.) Bielenberg, R.W., Reid, J.D., Faller, R.K., Rohde, J.R., Sicking, D.L., Keller, E.A., Holloway, J.C., Concept Development of a Short-Radius Guardrail System for Intersecting Roadways, Final Report to the Midwest State's Regional Pooled Fund Program, Transportation Research Report No. TRP-03-100-00, Project No. SPR-3(017)-Year 8, Midwest Roadside Safety Facility, University of Nebraska-Lincoln, September 12, 2000.
(8.) Bielenberg, R.W., Faller, R.K., E.A., Holloway, J.C., Reid, J.D., Rohde, J.R., Sicking, Phase II Development of a Short-Radius Guardrail System for Intersecting Roadways, Final Report to the Midwest State's Regional Pooled Fund Program, Transportation Research Report No. TRP-03-137-03, Project No. SPR-3(017)-Year 11, Midwest Roadside Safety Facility, University of Nebraska-Lincoln, September 9, 2003.