LONG-SPAN NESTED W-BEAM GUARDRAILS OVER LOW-FILL CULVERTS

A problem arises when it is necessary to continue a roadside guardrail across a low-fill box or pipe culvert. Full embedment of the guardrail posts is not possible over the culvert because of the shallow soil cover. Previous crash testing has demonstrated that posts with short embedment depths can be pulled out from the ground and subsequently fall into the path of the vehicle's tires, resulting in snagging or vaulting of the vehicle. For steel-post guardrails, one approach that has been successfully tested is bolting of the base plates of the short steel posts to the top of the box culvert. However, this design is not applicable to wood-post guardrail systems unless the posts are replaced with steel posts for the segment over the low-fill box culvert. This design also requires specially fabricated steel posts and additional labor for installation, resulting in considerably higher installation and maintenance costs. The results of a study to develop a design that is suitable for use with wood-post guardrail systems over low-fill culverts are summarized here. A computer simulation study was conducted to evaluate various alternative designs. The best design was then further evaluated through full-scale crash testing. The final design that was developed and successfully crash tested has no shallow embedment posts over the culvert and uses a nested W-beam rail to span the culvert. The design was tested for span lengths of 12 ft 6 in. (3.81 m) and 18 ft 9 in. (5.72 m). The additional costs associated with implementing this system are relatively low, consisting of two or three 12.5-ft (3.81-m) sections of W-beam rail elements and a little more labor. It is believed that the same design can be used for steel-post guardrail systems over low-fill culverts.

• Record URL:
  • http://onlinepubs.trb.org/Onlinepubs/trr/1992/1367/1367-006.pdf
• Record URL:
  • https://scholar.google.com/scholar_lookup?title=LONG-SPAN+NESTED+W-BEAM+GUARDRAILS+OVER+LOW-FILL+CULVERTS&author=K.+Mak&author=R.+Bligh&author=D.+Gripne&author=C.+McDevitt&publication_year=1992
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0309054087
• Supplemental Notes:
  • This paper appears in Transportation Research Record No. 1367, Development and Evaluation of Roadside Safety Features. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
• Authors:
  • Mak, King K
  • Bligh, Roger P
  • Gripne, Don J
  • McDevitt, Charles F
• Publication Date: 1992

Language

• English

Media Info

• Features: Figures; Photos; References; Tables;
• Pagination: p. 54-62
• Monograph Title: Development and evaluation of roadside safety features
• Serial:
  • Transportation Research Record
  • Issue Number: 1367
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Alternatives analysis; Costs; Crash tests; Crashes; Culverts; Design; Guardrails; Posts; Simulation; Testing; Wood
• Uncontrolled Terms: W beams; Wood posts
• Old TRIS Terms: Low-fill culverts
• Subject Areas: Bridges and other structures; Design; Finance; Highways; Research; Safety and Human Factors; I85: Safety Devices used in Transport Infrastructure;

Filing Info

• Accession Number: 00626732
• Record Type: Publication
• ISBN: 0309054087
• Files: TRIS, TRB
• Created Date: Feb 3 1993 12:00AM