B09_Amend_0002_Unnamed_Ck_Plan_1969_0002.pdf

This document is a set of detailed engineering drawings for the Unnamed Creek Bridge in Yellowstone National Park, dated May 1968. The drawings specify the complete structural design and construction requirements for a reinforced concrete bridge with steel railings, including plan views, elevations, cross-sections, and detailed reinforcement bar layouts.

The bridge design features a 143-foot total length with a clear roadway of 17 feet and includes six concrete spans at 16'-10" to 17'-10" centers, supported on concrete piers and abutments founded on cemented breccia or rhyolite rock. Construction specifications require Class A concrete with 1-inch maximum aggregate size, with concrete vibration and finishing per industry standards. Dead load capacity is specified at 150 pounds per square foot of roadway surface with earth pressure equivalent to fluid weight at 125 pounds per cubic foot. Live load accommodates AASHO 44 Loading Impact (1+1/5 span length) with maximum deflection of 1/300. Unit stresses are defined for concrete (allowable up to 1,200 psi for compression, 100 psi for tension) and reinforcement steel (Grade 40 deformed bars). The reinforcement bar list on the drawings provides detailed specifications for straight bars, bent bars, and bending diagrams for all structural elements including abutments, piers, footings, girders, diaphragms, wingwalls, and curbs, with specific bar sizes, lengths, spacing, and placement locations identified throughout the construction documents.