OR 140 East Seasonal Gate Closure Plan

This document is a structural design plan prepared by the Oregon Department of Transportation for seasonal gate closure operations on OR 140 Warren Highway near Chemult, Oregon (mileposts 38.42 and 65.15). The project involves the installation and operation of two closure gates at specified locations to control vehicle access during winter months. The design specifications reference the Oregon Standard Specifications for Construction 2024, AASHTO LRFD Bridge Design Specifications, and April 2025 edition of the Oregon Bridge Design Manual. The gates are manufactured closure systems designed for 34-foot widths at each location, with corresponding hold-back posts, gate posts with base plates, and associated structural hardware. The project requires installation of custom fold-up road signs (60x24 and 48x24 configurations) at multiple locations to inform motorists of the seasonal closure. Two additional "Road Closed Ahead" signs are specified at 9 and 38 miles before each gate location, along with "Next Gas 100 Miles" signage and existing gas station signage protection requirements.

The structural design specifications require all materials and work to conform to AASHTO standards, with reinforcing splices conforming to ASTM specifications (Grade 60 rebar with specific splice lengths detailed in the plans). Steel members must conform to AASHTO or ASTM standards with hot-dip galvanizing for structural steel and specified aluminum finishes per ASTM B221. Gate post installations include triangular base breakaway assemblies meeting AASHTO Standard Specifications for Structural Supports for Highway Signs with FHWA-approved Pole-Safe Model No. 4100 breakaway couplings (Transpo Industries). All welding must comply with AWS D1.1 for steel and AWS D1.2 for aluminum per the latest edition. The construction notes specify 2-closure gate installations with detailed footing, hinge connection, and breakaway coupling assemblies provided in the technical drawings. Site visits and field verification of gate locations and dimensions prior to fabrication are required.