Manual Notice: 2014-1
From: Rene Garcia, P.E
Manual: Roadway Design Manual
Effective Date: October 01, 2014Anchor: #URCLQECD
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.
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.
- 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.
- 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)."
- 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.
Updated "Throat Length" definition.Anchor: #DLWIXOQL
Contact the Roadway Design Section of the Design Division at (512) 416-2678 with any questions or comments.Anchor: #XQEDQKPR
Past manual notices are available in a pdf archive.