SECTION GUARDRAILS

SECTION 02845 GUARDRAILS PART 1 - GENERAL

1.01 SCOPE OF WORK

A. Furnish all labor, materials, equipment and incidentals necessary and repair, replace or install all types of guardrails as specified herein or required by Engineer.

B. Unless otherwise directed, the guardrail shall be replaced with W-beam guardrail or timber guardrail, as required by the Town.

1.02 SUBMITTALS

A. Submit to the Engineer, in accordance with Section 01300, shop drawings showing layout and details of construction and erection.

1.03 REFERENCE STANDARDS

A. Massachusetts Highway Department. Standard Specification for Highways and Bridges.

B. ASTM A 47 - Ferritic Malleable Iron Castings

C. American Wood Preservers Association (AWPA) standard C14 - Wood for Use in Highway Construction.

D. Where reference is made to one of the above standards, the revision in effect at the time of bid opening shall apply.

PART 2 - PRODUCTS

2.01 W-BEAM GUARDRAIL

A. Guard rail posts shall be constructed using a hardwood with a stress grade of 1000 psi or greater, extreme fiber in bending. Testing for stress grade shall be in accordance with Northeastern Lumber Manufacturer's Association, Inc., or Northern Hardwood and Pine Manufacturer's Association, Inc. Post shall be pressure treated with an approved preservative. If necessary, surfaces damaged by cutting, drilling or other method shall be field tested with a hot preservative.

B. Guard rail shall be W- beam Type SS and shall be made of weathering steel rails.

C. All splice bolts and nuts, washers and other accessories shall be made of weathering steel rails.

D. Terminal sections shall be installed at both ends of guardrail section.

2.02 CABLE GUARDRAIL

A. Cable guardrail shall be 2-cable (Type C-2-C) or 3-cable (Type C-3-S) cable guardrail furnished in accordance with Massachusetts DPW Construction Standards with wooden posts. If the existing guardrail is to be replaced, the H-beams shall be replaced with wooden posts, except otherwise required by the Engineer.

B. Cable shall be 19 mm (3/4 inch) wire rope meeting the requirements of AASHTO M 30, Type I Class coating.

C. Compensating devices shall have a spring rating of 78.8 kN/m ± 220 N (450 psi ± 50 psi) and have a total available throw of 150 mm (6 inches). The spring shall develop a minimum compressed strength of 120 kN (27,000 pounds) and be made from 14 mm (9/16 inch) diameter steel wire with a minimum breaking strength of 111 kN (25,000 pounds).

D. All fittings shall be designed to develop 445 kN (100,000 pounds) tensile strength for 3 cable assemblies. Wedge type cable socket fittings shall be of the open end type and permit visual inspection of the cable end and wedge after installation. Hook bolts shall develop an ultimate pull open strength of from 2.2 kN to 4.4 kN (500 pounds to 1,000 pounds) applied in the direction normal to the longitudinal axis of the post. Malleable steel fittings shall conform to ASTM A 47 or ASTM A 47M and be Grade 242-18.

2.03 POSTS

A. All new posts shall be of timber. No concrete or steel posts would be allowed, except otherwise required by the Engineer.

B. The bottom of the posts shall be sawed square, and the tops shall be rounded to a hemisphere. This sawing and rounding shall be performed at the source of supply, and not in the field. All posts shall be peeled by removing all of the rough bark and at least 80 percent of the inner bark. All knots and projections shall be shaved smooth and flush with the surrounding wood.

C. The posts shall be pressure treated after the sawing and rounding have been performed.

Post shall be pressure treated with an AWPA-approved preservative. If necessary, surfaces damaged by cutting, drilling or other method shall be field tested with a hot preservative.

2.04 TIMBER GUARDRAIL

A. All new posts shall be of timber. No concrete or steel posts would be allowed, except otherwise required by the Engineer.

B. Furnish timber conforming to AASHTO M 168. Fabricate the 6 by 10 inches timber rail

and (if required) 4x9 inches blockouts, from dry, well seasoned, and dressed rough sawn

Douglas fir, southern pine, or similar.

C. 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.

D. If required, fabricate the steel backing elements from structural steel and fastener hardware conforming to AASHTO M 222M.

PART 3 - EXECUTION

3 .01 GUARDRAIL REMOVAL

The guardrail shall be removed so that all material considered suitable by the Engineer for future use shall be salvaged. Posts having salvage value shall be removed without damage and those having no salvage value shall be pulled, or cut off at least 6 inches (150 mm) below the ground surface. All holes shall be filled and tamped. The salvaged material shall be stored at locations and in a manner approved by the Engineer. Any of this material having salvage value and which has been damaged by the Contractor shall be replaced at his/her own expense with new material of the same kind.

3 .02 POSTS

A. When pavement is within 3 feet of the guardrail, set posts before placing the pavement.

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

C. If an impenetrable object is encountered while placing posts, enlarge the hole to provide not less than 6-inch-clearance on all sides, and to a minimum depth of 30 inches. Set the post in concrete to within 6 inches of the top of the hole. Backfill and compact the remaining 5 inches with acceptable material.

D. Posts may be driven by an approved mechanical device. When, in the opinion of the Engineer, driving operations are producing unsatisfactory results, the posts shall be set in dug or bored holes. 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 5/8 inch. Set posts plumb, backfill, and compact.

E. When longer posts are specified, do not use them in the terminal sections. Stamp the post length on the top of all wood posts. Re-stamp numbers disturbed during installation.

3.03 W-BEAM GUARDRAIL INSTALLATION A. Wood Posts:

1. See paragraph 3.02 for posts installation requirements.

2. Posts may also be driven by an approved mechanical device. When, in the opinion of

the Engineer, driving operations are producing unsatisfactory results, the posts shall

be set in dug or bored holes.

3. Posts shall be spaced as shown on the Drawings or in accordance with manufacturer recommendations.

4. 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.

B. W- Beam Rails:

The rail shall be erected so as to form a smooth continuous rail conforming to the required line and grade as shown on the Contract Drawings and controlled by the grade of the finished roadway. The rail element shall be spliced by lapping in the direction of the traffic or by other approved methods. The holes in the rail element nearer the posts shall be slotted to facilitate erection and to permit expansion. The rail shall make full contact at each splice.

C. Standard Highway Delineators:

Standard white, reflective highway delineators will be installed every 12 feet at post locations, unless otherwise requested by the Engineer.

3.04 CABLE GUIRDRAIL INSTALLATION

A. Cable Guardrail Tensioning - Properly seat the spring compensation devices then permanently mark the unloaded position. Complete assembly of the cable guardrail and set the compensating devices to a spring compression of 88 mm (3 1/2 inches). Leave the springs at this setting according to the following:

METRIC ENGLISH

Temperature Spring Temperature Spring

Range Compression Range Compression

49 °C to 43 °C 25 mm 120 °F to 110 °F 1 inch

43 °C to 38 °C 32 mm 109 °F to 100 °F 1 1/4 inches

38 °C to 32 °C 38 mm 99 °F to 90 °F 1 1/2 inches

32 °C to 27 °C 44 mm 89 °F to 80 °F 1 3/4 inches

27 °C to 21 °C 50 mm 79 °F to 70 °F 2 inches

21 °C to 16 °C 57 mm 69 °F to 60 °F 2 1/4 inches

16 °C to 10 °C 63 mm 59 °F to 50 °F 2 1/2 inches

10 °C to 4 °C 69 mm 49 °F to 40 °F 2 3/4 inches

4 °C to - 1 °C 75 mm 39 °F to 30 °F 3 inches

No work shall be done during lower temperatures.

B. At all locations where the cable is connected to a cable socket with a wedge type

connection, crimp one wire of the wire rope over the base of the wedge to hold it firmly

in place.

C. Anchor Placement - Place the concrete anchors and backfill them at least two weeks prior to tensioning the cables. Set the concrete anchors into the excavation as shown. Set the bottom of the anchor so it has full and even bearing in the surface under it. Excavate and backfill according to Section 02300 EARTHWORK

3 .05 TIMBER GUARDRAIL

A. 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.

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

END OF SECTION