Steel-Backed Timber Guardrail

Section 617. GUARDRAIL          Section 710. FENCE AND GUARDRAIL


U.S. DOT logo

U.S. Department of Transportation 
Federal Highway Administration


Federal Lands Highways
"Commitment to Excellemce"

Section 617. GUARDRAIL


617.01 This work consists of constructing guardrail systems and modifying, removing, resetting, and raising existing guardrail systems.

(a) Guardrail systems are designated as follows:

G1 Cable guardrail

G2 W-beam (weak post)

G3 Box beam

G4 Blocked-out W beam standard barrier

G9 Blocked-out thrie beam standard barrier

MB4Blocked-out W beam median barrier

SBTASteel-backed timber guardrail/timber posts and block-out

SBTB Steel-backed timber guardrail/timber posts and no block-out

CRTW-beam guardrail and no blockout

SBLGSteel-backed log rail

(b) Steel guardrail types are designated as follows:

I Zinc-coated, 550 grams per square meter

II Zinc-coated, 1100 grams per square meter

IIIPainted rails

IV Corrosion resistant steel

(c) Steel guardrail classes are designated as follows:

A Metal thickness - 2.67 millimeters

B Metal thickness - 3.43 millimeters

(d) Terminal section types are designated as follows:

BCT Breakaway cable terminal

CRT Cable releasing terminal

MELT Modified eccentric loader terminal

G4-BATBack slope anchor terminal


617.02 Provide material conforming to the following Section and Subsec tions:

Box beam rail 710.07

Concrete 601

Corrosion resistant steel rail710.06(b)

Galvanized steel rail 710.06(a)

Guardrail hardware 710.10

Guardrail posts 710.09

Precast anchors 725.11

Reflector tabs 710.10

Retroreflective sheeting type I or type II 718.01

Steel-backed timber rail 710.08

Welding 555.03

Wire rope or wire cable 709.02

Wood preservative treatment716.03

Construction Requirements

617.03 Posts. When pavement is within 1 meter of the guardrail, set posts before placing the pavement.

Do not shorten guardrail posts unless the cut end is set in concrete. Do not shorten posts in terminal sections.

If an impenetrable object is encountered while placing posts, enlarge the hole to provide not less than 150 millimeters clearance on all sides, and to a minimum depth of 0.75 meters. Set the post in concrete to within 150 millimeters of the top of the hole. Backfill and compact the remaining 150 millimeters with acceptable material.

Drive posts into pilot holes that are punched or drilled. The dimensions of the pilot hole shall not exceed the dimensions of the post by more than 15 millimeters. Set posts plumb, backfill, and compact.

When longer posts are specified, do not use them in the terminal sections.

Stamp the post length on the top of all wood posts. Restamp numbers dis turbed during installation. Stamp post length on all metal posts. Galvanize after stamping.

Alternate hole arrangements do not apply to posts in the anchorage assembly.

617.04 Rail Elements. Install the rail elements after the pavement adjacent to the guardrail is complete. Do not modify specified hole diameters or slot dimensions.

(a) Steel rail. Shop bend all curved guardrail with a radius of 45 meters or less.

Erect rail elements in a smooth continuous line with the laps in the direc tion of traffic flow. Use bolts that extend at least 6 millimeters but not more than 25 millimeters beyond the nuts. Tighten all bolts.

Paint all scrapes on galvanized surfaces that are through to the base metal with 2 coats of zinc-oxide paint.

(b) Timber rail. Equally space bolts along the front face of the timber rail to match the holes in the steel backing. Align timber guardrail along the top and front edges of the rail.

Field cut timber rails to produce a close fit at joints. Treat field cuts with 2 coats of chromated copper arsenate.

(c) Log rail. Construct log rail according to the plans.

617.05 Terminal Sections. Construct terminal sections at the locations shown. Terminal sections consist of posts, railing, hardware, and anchorage assembly necessary to construct the type of terminal section specified.

Where concrete anchors are installed, construct either cast-in-place or precast units. Do not connect the guardrail to cast-in-place anchors until the concrete has cured 7 days. Install end anchor cables tightly without slack.

Use either the steel tube anchor or the concrete anchor in the construction of the anchorage assembly for the type BCT terminal section.

When required by the contract, construct earth berms according to Section 204.

617.06 Connection to Structure. Construct connection to structure and, where required by the contract, reinforced concrete transition according to the plans.

617.07 Removing and Resetting Guardrail. Remove and store the existing guardrail, posts, and appurtenances. Remove and dispose of posts that are set in concrete. Replace all guardrail, posts, and hardware damaged during removal, storage, or resetting. Backfill all holes resulting from the removal of guardrail posts and anchors with granular material according to Section 209.

617.08 Raising Guardrail. Remove the existing guardrail and appurte nances. Replace and reset posts as needed. Replace all guardrail, posts, and hardware damaged during the removal and raising.

617.09 Acceptance. Material for guardrail will be evaluated under Sub sections 106.02 and 106.03.

Construction of guardrail will be evaluated under Subsections 106.02 and 106.04.

Earth berm construction will be evaluated under Section 204.

Structural excavation will be evaluated under Section 209.

Welding will be evaluated under Section 555.

Concrete will be evaluated under Section 601.


617.10 Measure guardrail, except steel-backed timber guardrail and steel- backed log rail, by the meter along the face of the rail excluding terminal sections. Measure steel-backed timber guardrail and steel-backed log rail by the meter along the face of the rail including terminal sections. Measure transition sections from G9 rail to G4 rail as G9 rail.

Measure terminal sections by the each, except measure the following terminal sections as a part of the rail:

(a) Steel-backed timber guardrail terminal sections

(b) Steel-backed log rail terminal sections

(c) BCT anchorage assemblies constructed as a part of the CRT system

Measure removing and resetting guardrail and raising guardrail by the meter along the face of the rail including reset terminal sections.

Measure replacement posts (except replacement posts for posts damaged by construction operations) used in the removing, resetting, or raising guardrail by the each.

Measure connection to structure by the each.

Measure reinforced concrete transitions by the each.

Measure earth berms under Section 204.


617.11 The accepted quantities, measured as provided above, will be paid at the contract price per unit of measurement for the pay items listed below that are shown in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05.

Payment will be made under:

Pay Item Pay Unit

61701Guardrail system ____, type ___, class ___Meter

61702Terminal section type ___Each

61703Removing and resetting guardrailMeter

61704Raising guardrail Meter

61705Replacement posts Each

61706Connection to structureEach

61707Reinforced concrete transitionEach

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710.01 Barbed Wire. Furnish galvanized wire conforming to AASHTO M 280 or aluminum coated wire conforming to AASHTO M 305 type I.

710.02 Woven Wire. Furnish galvanized fabric conforming to AASHTO M 279 or aluminum coated fabric conforming to ASTM A 584.

710.03 Chain Link Fence. Furnish fabric, posts, rails, ties, bands, bars, rods, and other fittings and hardware conforming to AASHTO M 181.

Furnish 4.5-millimeter coiled spring steel tension wire conforming to ASTM A 641M hard temper with a class 3 galvanized coating or an aluminized coating having a minimum coating mass of 120 grams per square meter of aluminum. Use the same coating on the tension wire as used on the rest of the chain link fence.

710.04 Fence Posts.

(a) Wood. Conform to AASHTO M 168.

Peel all bark, except for red cedar posts and bracing which do not require peeling. Trim all knots flush with the surface and season the wood.

For dimension lumber for fences or gates, use timber that is sound, straight, and reasonably free from knots, splits, and shakes. Provide an S4S finish.

(b) Concrete. Conform to Section 601.

(c) Steel. For line fence posts, conform to AASHTO M 281. For chain link fence, conform to AASHTO M 181.

710.05 Fence Gates. For frame gates used with chain link fences, conform to AASHTO M 181. Use the same chain link fabric in the gate and the fence.

710.06 Metal Beam Rail.

(a) Galvanized steel rail. Furnish W-beam or thrie beam rail elements fabricated from corrugated sheet steel conforming to AASHTO M 180 for the designated shape, class, type, and mass of coating specified.

(b) Corrosion resistant steel rail. Furnish W-beam or thrie beam rail elements and associated weathering steel hardware conforming to the following:

(1) Shapes and platesAASHTO M 222M

(2) Rail elementsASTM A 606 type 4

(3) Fasteners AASHTO M 164M type 3

710.07 Box Beam Rail. Furnish steel box beam rail elements conforming to the AASHTO-AGC-ARTBA A Guide to Standardized Highway Barrier Hardware, 1995 edition.

710.08 Steel-Backed Timber Rail. Furnish timber conforming to AASHTO M 168. Fabricate the 150 by 250-millimeter timber rail and the 100 by 225-millimeter blockouts from dry, well seasoned, and dressed rough sawn Douglas fir, southern pine, or other species having a stress grade of at least 10 megapascals.

Treat the timber rail and blockout elements with CCA, ACZA, or ACA preservative treatment conforming to AWPA C14 except the minimum retention shall be 9.6 kilograms per cubic meter.

Fabricate the steel backing elements from 9.5-millimeter structural steel conforming to AASHTO M 222M. For fastener hardware, conform to AASHTO M 222M.

710.09 Guardrail Posts.

(a) Wood posts. 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 75 millimeters of the bolt hole.

(b) Box beam posts. Conform to the AASHTO-AGC-ARTBA A Guide to Standardized Highway Barrier Hardware, 1995 edition.

(c) Steel-backed timber posts. Furnish 250 by 300-millimeter guardrail posts conforming to Subsection 710.08. Post lengths will be specified in the contract.

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

Make all angles, channels, wide flanges, and plates not contained in the above standard conform to ASTM A 36M, except make the structural tubing for the short steel post conform to ASTM A 500 or ASTM A 513 grade 1008. Galvanize soil plates and structural tubing according to ASTM A 123. Do not punch, drill, cut, or weld the metal after galvanizing.

Manufacture reflector tabs from 4-millimeter aluminum or galvanized steel sheets. Use an adhesive that resists peeling with a force of 0.89 kilograms per centimeter of width. Use mildew resistant adhesive which has no stain ing effect on retroreflective sheeting.

710.11 Temporary Plastic Fence. Furnish plastic noncorrosive fence fabri cated from polyethylene (HDPE) and UV stabilized for outdoor weathering. Conform to the following:

(a) Height 1200 mm min.

(b) Mesh openings 80 to 85 mm

(c) Color International orange

(d) Mass 0.25 kg/m min.

710.12 Crash Cushion Barrels. Furnish 900-millimeter diameter barrels made of high-density polyethylene structural foam or equal material. Furnish lids of the same material as the barrels, but of a thinner gauge. Furnish appropriate height cores made of polystyrene or equal material.

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