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Manual Notice: 2014-1

From: Rene Garcia, P.E

Manual: Roadway Design Manual

Effective Date: October 01, 2014

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Purpose

Appendix A and Appendix C are being revised:

  • To update guidance for 31 inch guard fence;
  • To add guidance on median barriers;
  • To reflect terminology changes in a previous revision to Chapter 2;
  • To update the definition of Throat Length in Appendix C; and
  • To make editorial and technical corrections.
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Contents

Appendix A

Changed "guardrail" to "guard fence" throughout.

Changed "horizontal clearance" to "clear zone" throughout.

Added linked text to metric versions of Figures, Tables, and Example Problems.

Title: changed from Metal Beam Guardrails to Longitudinal Barriers.

Section 1, first paragraph: added "median" traffic barrier to objectives of Appendix A.

Section 2,

  • first paragraph: updated wording for clarity,
  • fourth paragraph: moved to Section 6,
  • fifth paragraph: added "10 feet" to the area free of obstructions,
  • Figure A-2 (M): removed and combined with Figure A-1. Subsequent Figures renumbered.

Section 3,

  • title: changed from "Structural Considerations" to "Structural Considerations of Guard Fence,"
  • first paragraph: added "location" to important factors,
  • subsection Rail Element, second paragraph: changed rail mount from 21 inches to 25 inches high, added "The rail element shall be spliced midspan between the posts,"
  • third paragraph: specified allowable tolerances for 31" and 27" systems,
  • fourth paragraph: completely revised to accommodate 31" system, if existing 27" system is raised,
  • subsection Blockouts: new subsection.

Section 4, Subsection Lateral Placement at Shoulder Edge or Curb Face, second paragraph: changed post bolt from 21 inches to 25 inches above the gutter pan or roadway surface.

Section 5, second paragraph: updated "end terminal anchor" to "Downstream Anchor Terminal (DAT)."

Section 6,

  • Subsection Variables, third paragraph: added discussion on Lu, upstream, and Ld,
  • Figure A-7, Variable Involved in Barrier Layout: redrawn to add design speed, upstream, and downstream options,
  • Subsection Design Equations: reformatted to include upstream and downstream equations which are referenced in the Section 7, removed metric from text and placed it in a linked document. Added discussion and equation for "length of need."

Section 7: updated example problems to reflect changes in appendix.

Section 8: Median Barrier, new section.

Section 9: Emergency Crossovers, new section.

Appendix C

Updated "Throat Length" definition.

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Contact

Contact the Roadway Design Section of the Design Division at (512) 416-2678 with any questions or comments.

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Archives

Past manual notices are available in a pdf archive.

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