96E03/29/06

S710-96E.doc

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  Use with wood guardrail posts.

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**Section 710. - FENCE AND GUARDRAIL**

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  When steel backed timber rail is specified, include the following:

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**710.08 Steel-Backed Timber Rail.** [Delete the text and substitute the
following:]{.underline}

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  Edit the following as necessary. See commentary for SCR 716.03 for
  discussion of preservative treatment alternatives. If CCA is not to be
  used, delete last sentence. If copper naphthenate is used, change
  minimum retention to 2lb/yd^3^.

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Furnish timber conforming to AASHTO M 168. Fabricate the 6 by 10 inch
timber rail, the 4 by 9 inch blockouts, and the posts from dry, well
seasoned, and dressed rough sawn coast Douglas fir, southern pine, or
other species having a stress grade of at least 1500 psi. Refractory
species such as larch and Rocky Mountain Douglas fir are not acceptable.
Treat the timber rail, blockout elements, and posts according to AASHTO
M 133.

Fabricate the steel backing elements from ⅜ inch structural steel
conforming to ASTM A588. For fastener hardware, conform to AASHTO M 164,
type 3.

All timber members shall bear an approved ALSC (American Lumber
Standards Committee) quality mark assuring treatment is in conformance
with appropriate AWPA standards.

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  Use with guardrail posts.

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**710.09 Guardrail Posts.** [Delete the text and substitute the
following:]{.underline}

Conform to the AASHTO-AGC-ARTBA "Guide to Standardized Highway Barrier
Hardware," 1995 edition.

Do not use a wood guardrail post that has a through check, shake, or end
split in the same plane as, or a plane parallel to the bolt hole and
extending from the top of the post to within 3 inches of the bolt hole.

For steel-backed timber rail posts, furnish 10 by 12 inch posts
conforming to Subsection 710.08.

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  When temporary crash cushions are required, include the following:
  **NOTE TO DESIGNER:** This subsection is being handled in subsection
  635.19.

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**710.12 Crash Cushion Barrels.** [Delete the text.]{.underline}

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  Use the following for UPS projects with log rails. Verify copper
  naphthenate preservative is acceptable.

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[Add the following subsection:]{.underline}

**710.13 Log Rails.**

Use logs that are seasoned, straight, and sound No. 1 Grade Western
Hemlock, Western Red Cedar, or Pine of the dimensions shown on the
drawings. Logs that taper in excess of 1.2 inches will not be permitted.
Remove all bark and at least 80% of the inner bark. Peeler marks or
incision marks on visible portions of logs will not be allowed. Utilize
logs that do not have a season checks, singular or any 2 opposite each
other that exceed 2 the thickness of the member. Incorporate logs that
are free of knot clusters, but may contain sound, tight, well-spaced
knots.

Incise that portion of the log which will be below ground. Make all
dimensional cuts and holes in the timber members prior to pressure
treatment. Treat all timber members with Copper Naphthenate preservative
treatment conforming to AWPA C14. Preservative retention in the assay
zone shall not be less than 2 pounds per cubic yard. Assay only in the
incised, below ground portion of the posts.

All timber members shall bear an approved ALSC (American Lumber
Standards Committee) quality mark assuring treatment is in conformance
with appropriate AWPA standards.