Ponderosa Pine Round Posts as Alternative to Rectangular SYP Posts in Retrofit G4(2W) Guardrail Systems
Over the last several decades, the southwestern United States experienced numerous forest fires, prompting a need for more preventive techniques. In the 1960s, the U.S. Department of Agriculture - Forest Service began managing fuels by using controlled-burn techniques. However, due to both the lack of economic benefits and the high risk involved with controlled-burn methods, more cost-efficient methods were sought to remove the smalldiameter forest thinnings. With such vast quantities of timber thinnings, local producers within the timber industry deemed it necessary to further explore the use of undamaged Ponderosa Pine (PP) material as posts in guardrail systems. Two W-beam guardrail systems were identified that may be compatible with PP posts: the U.S. standard G4(2W) guardrail system and the Arizona DOT (AzDOT) G4(2W) guardrail system. Therefore, research was undertaken to determine the appropriate dimensions (diameter and length) and embedment depth of round PP posts for use within these two strong-post, W-beam guardrail systems. Dynamic component tests on rectangular SYP posts and round PP posts with diameters between 8⅜ in. and 8¾ in. were performed to determine the appropriate diameter, length, and embedment depth for PP posts to be used as a surrogate for 6-in. x 8-in. rectangular Southern Yellow Pine (SYP) posts found in existing, strong-post, G4(2W) Wbeam guardrail systems. In addition, one full-scale demonstration crash test was successfully performed according the Test Level 3 (TL-3) impact safety standards published in the National Cooperative Highway Research Program (NCHRP) Report No. 350 on a 175-ft long, G4(2W) guardrail system supported by 8½-in. diameter (ground line) by 64-in. long PP posts with a 35-in. embedment depth. A ¾-ton Chevrolet pickup truck impacted at a speed of 60.7 mph and an angle of 24.8 degrees. The G4(2W) guardrail system with PP posts adequately contained and redirected the pickup truck and met the NCHRP 350 TL-3 safety performance criteria. Based on dynamic component testing, a PP post with an 8½-in. diameter, a 35-in. embedment depth, and a 64-in. length was approved for use as a surrogate in existing Arizona G4(2W) guardrail systems. Similarly based on the dynamic component testing, a PP post with an 8⅝-in. diameter, a 36-in. embedment depth, and a 65-in. length was also approved for use as a surrogate in existing U.S. standard G4(2W) guardrail systems. The demonstration test offered confidence to State Departments of Transportations interested in using round PP posts to repair damaged strong-post, W-beam guardrail systems configured with 6-in. x 8-in. rectangular SYP posts.
- Record URL:
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Availability:
- Find a library where document is available. Order URL: http://worldcat.org/issn/00978515
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Authors:
- Lechtenberg, Karla A
- Faller, Ronald K
- Reid, John D
- Rosenbaugh, Scott K
- Kretschmann, David E
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Conference:
- First International Roadside Safety Conference
- Location: San Francisco California, United States
- Date: 2017-6-12 to 2017-6-15
- Publication Date: 2017-6
Language
- English
Media Info
- Media Type: Digital/other
- Features: Figures; Photos; References; Tables;
- Pagination: pp 89-102
- Monograph Title: First International Roadside Safety Conference: Safer Roads, Saving Lives, Saving Money
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Serial:
- Transportation Research Circular
- Issue Number: E-C220
- Publisher: Transportation Research Board
- ISSN: 0097-8515
Subject/Index Terms
- TRT Terms: Guardrails; Highway safety; Lumber; Posts; Retrofitting
- Subject Areas: Bridges and other structures; Highways; Materials; Safety and Human Factors;
Filing Info
- Accession Number: 01646127
- Record Type: Publication
- Files: TRIS, TRB, ATRI
- Created Date: Sep 18 2017 8:43AM