SECTION 221—GUARDRAIL
221.01 Description
These specifications cover material requirements for components of guardrail systems.
221.02 Detail Requirements
Guardrail shall consist of rail or cable elements and fastenings fabricated to develop continuous beam or cable strength when installed. Guardrail materials conforming to AASHTO M180 and M30 specifi - cation requirements shall be supplied by manufacturers included on the Department’ s Approved List 12. Manufacturers of guardrail materials shall participate and be in compliance with the AASHTO National Transportation Product Evaluation Program Evaluation of Highway Guardrail Manufacturers.
a.Steel beam shall conform to AASHTO M180, Class A, T ype 1. Where guardrail is to be constructed on curves that have a radius of 150 feet or less, rail elements shall be shop curved to the proper radius, with the roadside of the rail either concave or convex as required.
b.Wire rope (cable) shall conform to AASHTO M30, T ype I, Class A. 220.02
c.Brackets, turnbuckles, compensating assemblies, and attachment hardware shall be of sufficient design and section to develop the full strength of the cable guardrail and shall be galvanized in accordance with ASTM A153. The spring compensating device shall have a spring constant of 450 ± 50 pounds and shall permit a travel of 6 ± 1 inches.
d.Concrete for precast reinforced concrete posts shall conform to Section 217 for Class A3, except that T ype I cement and a smaller size of aggregate may be used.
e.Steel posts shall be galvanized in accordance with AASHTO M111.
1.Structural rolled shapes shall conform to ASTM A709, Grade 36.
2.Sheet steel for fabricated shapes shall conform to ASTM A1011, Grade 36.
3.Weld-fabricated shapes shall conform to ASTM A769.
f.Wood posts shall conform to Section 236 and shall be pressure treated.
g.Anchor bolts shall conform to Section 226.02(c) for high-strength bolts.
h.Offset blocks shall conform to either of the following:
1.Shall be pressure treated wood conforming to Section 236; or
2.Shall be made of plastic or rubber and contain a minimum of 40 percent recycled post- consumer and post-industry waste. Block attachment shall be in accordance with the details and dimensions of the Standard Drawings for wooden posts, Standard GR-2, 2A W-Beam guardrail. The size tolerance in the direction of the bolt hole shall not be more than 1/4 inch. The blocks shall present a neat appearance and have planed surfaces. The manufacturer of the recycled blocks shall provide independent test results showing that the material complies with the velocity, acceleration, and post-impact trajectory requirements of National Cooperative Highway Research Program (NCHRP) Report 350 or Manual for Assessing Safety Hardware (MASH). The manufacturer shall certify that the material components of the completed blocks are weather resistant and manufactured to prevent ultra-violet (UV) degradation. The manufactur- er shall also certify that the material components of the completed blocks are resistant to the subterranean termites during its theoretical lifetime when tested according to ASTM D3345. The theoretical lifetime is considered to be at least 20 years. Any block that varies from the materials herein or from the dimensions and tolerances in the Road and Bridge Standards shall be submitted for approval. 221.02
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Source: Road and Bridge Specifications, 2020 Edition. Pages 246–247 of 1,065. View official source ↗