1、Section 20 RAILINGS 20.1 GENERAL 20.1.1 Description This work consists of furnishing all materials and con- structing railings on structures. The types of railings in- cluded in this work consist of handrailings, pedestrian railings, traffic railings which are sometimes called barri- ers, and railin
2、gs for other such purposes. Railings con- structed at each location shall conform to the type and de- tails shown on the plans for that location. The work includes the furnishing and placing of mortar or concrete, anchor bolts, reinforcing steel dowels or other devices used to attach the railing to
3、the structure. 20.1.2 Materials All materials not otherwise specified shall conform to the requirements of the applicable AASHTO Standard Spec$cations for Transportation Materials. 20.1.3 Construction Unless otherwise permitted by the Engineer, railing shall not be placed until the centering or fals
4、ework for the span has been released, rendering the span self-supporting. 20.1.4 Line and Grade The line and grade of the railing shall be true to that shown on the plans and may include an allowance for camber in each span but shall not follow any unevenness in the superstructure. Unless otherwise
5、specified or shown on the plans, railings on bridges, whether super-elevated or not, shall be vertical. 20.2 METAL RAILING 20.2.1 Materials and Fabrication 20.2.1.1 Steel Railing Materials and fabrication of steel railings shall con- form to the applicable requirements of Section 11, “Steel Structur
6、es,” except that formed sections may be fabri- cated from mild steel, and pipe sections shall be of stan- dard steel pipe. Nuts and bolts not designated as high strength shall conform to the requirements of ASTM A 307 and steel tubing shall conform to the requirements of ASTM A 500, Grade B. 20.2.1.
7、2 Aluminum Railing For aluminum railings or portions of railings, cast alu- minum posts shall conform to the requirements of AASHTO M 193; and extruded components shall con- form to the requirements of ASTM B 221. 20.2.1.3 Metal Beam Railing Metal beam rail, posts and hardware shall conform to the r
8、equirements in Section 606 of the AASHTO Guide Specjications for Highway Construction. 20.2.1.4 Welding All exposed welds shall be finished by grinding or fil- ing to give a smooth surface. Welding of aluminum mate- rials shall be done by an inert gas shielded, electric arc welding process using no
9、welding flux. Torch or flame cutting of aluminum will not be permitted. 20.2.2 Installation Metal railings shall be carefully adjusted prior to fix- ing in place to ensure proper matching at abutting joints, correct alignment, and camber throughout their length. Holes for field connections shall be
10、drilled with the rail- ing in place on the structure at proper grade and align- ment. Where aluminum alloys come in contact with other metals or concrete, the contacting surfaces shall be thor- oughly coated with a dielectric aluminum-impregnated caulking compound, or a synthetic rubber gasket may b
11、e placed between the two surfaces. 637 638 HIGHWAY BRIDGES 20.2.3 20.2.3 Finish Unless otherwise specified, anchor bolts, nuts and all steel portions of railings shall be galvanized and alu- minum portions shall be unpainted. Galvanizing of rail el- ement shall conform to the requirements of AASHTO
12、M 11 1 (ASTM A 123) and galvanizing of nuts and bolts shall conform to the requirements of AASHTO M 232 (ASTM A 153). Minor abrasions to galvanized surfaces shall be repaired with zinc rich paint. After erection, all sharp pro- trusions shall be removed and the railing cleaned of dis- coloring forei
13、gn materials. When painting is specified, the type and coating shall conform to the requirements of Section 13, “Painting,” or the special provisions. 20.3 CONCRETE RAILING 20.3.1 Materiais and Construction Concrete railings, depending on the design, may be constructed by the cast-in-place, precast
14、or, when ap- proved by the Engineer, the slip form method. All materials and construction shall conform to the re- quirements in Section 8, “Concrete Structures” and Sec- tion 9, “Reinforcing Steel.” Unless otherwise specified, concrete shall conform to Class AE except that Class A may be used in ar
15、eas where freezing seldom occurs. When the minimum thickness of the railing at any point is less than 4 inches, Class C (AE) or, where freezing seldom oc- curs, Class C concrete may be used. Forms for cast-in- place railing shall not be removed until adequate mea- sures to protect and cure the concr
16、ete are in place and the concrete has sufficient strength to prevent surface or other damage caused by form removal. Finish for railings con- structed with fixed forms shall be Class 2-Rubbed Finish. Finish for railings constructed with slip forms and for temporary railings shall be Class I-Ordinary
17、 Finish. 20.4 TIMBER RAILING Unless otherwise stated in the special provisions, posts, rails, and other timber for wood railings shall be constructed according to the requirements of Section 16, “Timber Structures,” and Section 17, “Preservative Treat- ment of Wood.” When treated wood is called for,
18、 the preservative treatment shall conform to the requirements of Section 17, “Preventive Treatment of Wood.” The sur- faces of all elements of treated wooden railings that are lo- cated where contact with people could occur shall be sealed with two coats of an acceptable sealer. Acceptable sealers a
19、re urethane, shellac, latex epoxy, enamel and var- nish. 20.5 STONE AND BRICK RAILINGS Stone and brick railings shall conform to the require- ments of Section 14, “Stone Masonry,” and Section 15, “Concrete Block and Brick Masonry.” 20.6 TEMPORARY RAILING Temporary railings shall be constructed of ma
20、terials and to the details shown on the plans or specified. Railings shall be properly joined and aligned at the required loca- tions. Temporary precast barriers shall be installed on a solid base. The temporary railing shall be maintained in first class condition and shall not be removed until all
21、work requiring the railing has been completed. Previously used units may be employed provided they are in a clean and undamaged condition. After removal, temporary rail- ing shall continue to be the property of the Contractor. 20.7 MEASUREMENT AND PAYMENT 20.7.1 Measurement Railings will be measured
22、 by the linear foot between the ends of the railing or the outside ends of end posts, whichever is greater. Measurement will be made along the slope of the railing and no deductions will be made for electrolier or other small openings called for on the plans. 20.7.2 Payment Railings will be paid for
23、 by the contract prices per lin- ear foot for the various types listed in the schedule of bid items. Such payment shall include full compensation for furnishing all labor, materials, equipment and incidentals and for doing all work involved in constructing the rail- ings or barriers complete in place, including the furnish- ing and installation of reinforcing steel and steel dowels or anchor bolts which are either placed or drilled and bonded into the structure for attachment of the railing.
