Designs for the Halsey Street-2nd Street Bridge and Off-Street Multi-Use Trail
Datum
2021-06
Autor:innen
Zeitschriftentitel
ISSN der Zeitschrift
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Verlag
University of Oregon
Zusammenfassung
The City of Troutdale wishes to develop a proposal for a pedestrian bridge that crosses Southwest 257th Drive near downtown Troutdale, approximately 200 feet south of the intersection with Historic Columbia River Highway. The project is identified in the City’s Town Center Plan and is expected to be discussed in a three-city “Main Streets on Halsey” corridor planning effort in 2021. There have been no formal engineering studies done, though hypothetical designs have been rendered. This proposal would seek to connect a prospective off-street multi-use trail from Halsey Street (to the west) to 2nd Street (to the east) over 257th Drive, a major arterial road and freight route. This would enhance connections between downtown and residential areas to the west, and improve safety for pedestrians and bicyclists. The Portland State University Halsey-2nd Bridge Capstone group was employed to produce a 30% design or initial designs leading to a 30% design. Also desired are costing estimates for additional design/permitting/construction that could take place in a five-year horizon, plus feedback from Multnomah County and City engineers to highlight permitting requirements or conditions. The City would like design considerations to be made for bicycle and neighborhood electric vehicles such as golf carts. Inspiration should be taken from a recent bridge installation connecting Pier Park and Chimney Park in north Portland. In designing the bridge, the Capstone group determined through analysis that a steel truss would be the best structural system to use. Shop-fabricated steel trusses are widely accepted as the ideal option for pedestrian bridges. The proposed design is a 140-foot-long single-span truss with a deck that has 14 feet of clear width. The truss type is a Pratt truss, with 14 panes that are each 10 feet square and which have 45 degree diagonals. The truss will be composed of Grade 50 steel. The bridge deck will be a reinforced concrete slab that rests on 18-gauge corrugated steel decking, and which is simply supported in the transverse direction relative to the long axis of the bridge. The slab will be 6.25 inches high in total, with #9 rebar placed every 12 inches. The bridge will be simply supported by concrete abutments, one on each side of 257th Drive. Each abutment will be a 2-foot-thick stem wall, at the top of which is a 10-inch-thick bearing pad and a 6-inch-thick back wall that extends 2 feet above the stem wall. The abutments will each have a spread footing foundation with a width of 18 feet and a thickness of 2.5 feet. The foundation on the west side of the road will have a back wall height of 12.5 feet. On the east side the back wall will be 10.5 feet high. The foundations will have wing walls to retain the soil in the backfill, which will consist partially of Geofoam. The wing walls will be 8 inches thick and will extend 10 feet back, perpendicular to the stem wall. The bridge will cross 257th Drive in a direction perpendicular to the road. The vertical clearance between the bridge and the road will be 18 feet. Trails connecting the bridge westward to Halsey Street, and eastward to 2nd Street, will be shared-use pathways that are 14 feet wide. Ramps are used to connect the trails with the elevated bridge The bridge and trails will conform with the standards of the American Association of State Highway and Transportation (AASHTO), or with superseding local and state regulations where necessary. The start-to-finish construction time is estimated to be around 20 weeks. The total cost for the completed facility, if constructed in 2026, is estimated to be $1,943,538.
Beschreibung
355 pages